Questions & Answers

This page contains questions (edited) we have received from our viewers along with our responses.  
We thought you might find this information helpful.       


   When is the best time to plant a Red Bud tree in Boulder? S. K., Boulder, 1/20/12

A:    The best time to plant trees in Boulder is spring. Summer weather is too hot and stresses newly planted trees, sometimes resulting in death. Fall is the second best time.

   We just moved into a house and there is a cottonwood growing behind a retaining wall, and the roots are curled around behind the wall. This tree has also had cement castoff poured on one side, and the bark on that side is very soft. The leaves turned yellow and fell off in August. I am wondering if there is anything I can do. Thanks.  E., Denver, 12/13/11

A:    Early fall color and leaf drop are signs that the tree is under stress. The soft bark is also a concern. About all you can do at this point is try to improve the tree's vigor by careful winter watering. Water the tree when there is no snow on the ground and the temperature is above 40 degrees. In spring you may want to have a tree service company evaluate the health of the tree as well as determine if it is safe or possibly in danger of falling.

   I have 2 linden trees.  The tree in the backyard dropped its leaves weeks ago.  The tree in the front has not dropped the leaves and they are curled up and brownish green in color.  Is the tree OK?  C. Denver, 12/6/11

   Each plant lives in its own unique microclimate. The amount of light (both sunlight and artificial light), heat - including reflected heat, moisture, etc., that each plant receives varies and can affect the timing of fall color and leaf drop in leaves. Because we have had some really cold weather, I suspect that the leaves on the tree in front died after being frozen. The tree itself is probably fine. If snow, rain or wind don't cause the leaves to drop eventually, you can spray the tree with a strong jet of water to knock them off the tree in late winter.

   We have a "Charlie Brown" red maple.  I just got to thinking maybe it is a "Charlie Brown" because it is too close to the pine trees.  There is an abundance of pine needles blanketing the ground and a build up of the same from years of being there.  Do you know how we can help this tree - do we need to remove either the pine trees or move the maple?  Thank you.  G., Littleton, 9/27/11

   Moving trees is risky because there is a good chance the tree could die. Is it possible that the maple is a small variety of maple, such as Amur Maple or a Japanese Maple? I doubt that the pine needles are the problem. Too much heavy shade from the pines could be a factor, however. Extra water and fertilizing the tree in spring may encourage growth.

   Our Autumn Blaze Maple tree is yellow from lack of iron in our soil.  We have had no luck with 4 different trees in this spot during the past 35 years.  We are going to lose this tree too if we can't get the right nutrient.  When is the right time to apply iron, and what kind?  Any advice will be welcome.  K. R., Greeley, 9/10/11

A:    You should apply chelated iron to the soil. Apply it throughout the maple tree's root zone, not just close to the trunk. You might want to wait until early spring to apply it. A soil test might be helpful to identify any other soil deficiencies.

   I have a fairly large Austrian Pine. I trimmed the lower branches off the tree to a height of about 4ft. Will this gap of 4ft to the ground increase over time, or will it always be the same? My wife is very upset with me. She says the gap is going to get bigger. I thought Austrian Pines grew from the tips of the branches. Thank You, A., Parker, 8/28/11

   Tell your wife she can relax. The space won't get any larger. The tree grows from the tips of the branches.

   We just planted an aspen about 3-4 weeks ago. The tree is about 15 ft tall and seemed healthy. We live near COS at 7000 ft elev.  We have watered it.  It leafed out.  Now the leaves are black and curling up.  We also have grass mulch around the base.  We water it regularly.  Is it too much?   Is the mulch a problem?  C. B., Black Forest, 6/23/11

   The aspen tree is probably going through transplant shock. Water it thoroughly and allow the soil to dry out almost completely between waterings. Only use grass as a mulch if the grass hasn't had weed and feed products used on it or other kinds of weed killers.

   I have a Linden tree that did not get leaves this spring.  It has growth on the trunk but no leaves.  We had late frost this year.. would that be why?  L. K., David City, NE; 5/19/11

   If the leaf buds of the linden tree were damaged by frost the tree should produce a second set of leaves.  Fertilize it lightly and keep it well watered.

   We are moving to a new house in the north Thornton area.  We would like to plant  some trees for privacy that are not wide because of the limited space.  We love evergreens.  We don't like spraying.  What are your suggestions?  What month is the best for planting?  B. F., Thornton, 1/2/11

   You should measure the space where you plan to plant the trees so you know exactly how wide the mature trees can be.  Then, please see the article "Evergreen Trees" at You can glance through the list to find trees that fit your space.  Most evergreens do well in the sun.  Arborvitae, however, should not be planted where they receive afternoon sun.  The best time to plant evergreens is early spring.  Do not plant them in summer or fall.

   What would you recommend be done for a small, 8-10" wound on the bark of an aspen tree?  It did not penetrate into the meat of the tree. Should a dressing and wrapping be applied?  We are at 9800' in the San Juan mountains.  Thank you for any help you can give me.  C. M., Silverton, 12/19/10

A:    You do not need to do anything to the wound in the bark of the aspen at this time.  The tree will heal the wound by creating a callous over it.  In spring you might spray the wound with fungicide to kill any organisms that may begin to grow there.

   I bought some cottonless cottonwood trees for my large backyard. The nursery said it was a hybrid type that did not have brittle branches. Is there such a thing and also do they have destructive root systems?  P. T., Laredo, TX; 11/23/10

   Cottonless cottonwood trees belong to the Poplar family, which is known for its invasive roots.  Members of this family should be planted away from septic systems and water pipes.  Cottonwood trees are prone to brittle branches -- I don't know if that is true of the hybrid you bought.

   I'm looking for a small ornamental tree for full sun - not spring flowering.  J. P., Lakewood, 7/30/10

   Most small ornamental trees have blossoms, so choices are limited.  You might consider Amur Maple, Tatarian Maple or Rocky Mountain Birch.

   I am looking for trees to plant in my garden -- something that will stay under 4 ft tall-possibly bonsais?? Any suggestions?  Thanks, R. D., ?, 7/27/10

A:    There are dwarf conifers that will stay small, such as Dwarf Alberta Spruce 'Jean's Dilly', Dwarf Balsam fir and some kinds of Arborvitae, for example.  They can be difficult to find, are slow growing, and therefore, are expensive. 

   About 1 month ago, we purchased a Redspire flowering pear in a container and planted it in the same spot as was our former Black Hawk Mountain Ash.  We did what we were told... which was to amend the soil and add a root stimulator.  Since then, we had that large snow - now melted.  While the tree looks healthy and leaves are coming out abundant... there were no flowers.  Did we do anything wrong?  Also, we were told not to fertilize, but should we treat with Bayer's insect product for protection?  Thanks in advance for your time and advice.  C. A., Loveland, 4/19/10

   Cold weather when the Redspire flowering pear was about to blossom or being newly transplanted could cause the tree not to blossom.  Don't spray for insects at this time.  Watch the tree in the coming months and spray only if the tree develops a problem with them.  Water the tree regularly, but don't keep the soil soggy.  If the leaves begin to yellow and the soil is moist, cut back on the amount and frequency that you are watering. 

   When is the best time to trim limbs from pine trees?  S. R., Fort Garland, 3/23/10

A:    Pine trees can be pruned in early spring (March - April).

   When is the best time to trim a flowering pear tree? S. P., Denver, 1/31/10

A:    The best time to trim a flowering pear tree is in late winter or early spring before it leafs out.

   I live at 8,000 ft.  I would like to plant a Maple tree.  Would this be advisable at this altitude?  D. V., Morrison, 1/25/10

   Large, shade tree maples will not do well at 8000 ft.  There are small maples that will survive.  Please see this fact sheet for information on small maples and other kinds of trees that perform well in the mountains:

   My new 3' Golden European potted fir tree is starting to turn from its bright lime green color to a blonding-brown at the top. Am I killing it?  Thanks so much.  J. C., San Francisco, CA; 12/9/09

A:    Please be sure to water the potted fir tree regularly.  Plants that die from the top down or from the outside toward the inside often are not receiving enough water.  Keep the soil slightly moist but not soggy.  Do not let the plant sit in water.  The potted fir should receive bright filtered light.

   I am having problems with kids carving their names into my aspen trees. The base of the trees also have been hit with weed whackers. Is there anything you can put over the wounds to hide them?  S. W., Show Low, AZ; 11/28/09

   There isn't anything you should put over the wounds in the aspen trees to hide them.  However, there are plastic protectors you can buy to place around the base of the tree trunks to protect them from weed whacker wounds.  The wounds create entry points for pests and diseases, so it is important to prevent them when possible.
Q:    We live at 7000 feet.  When is the best time of the year to transplant Ponderosa Pines to our yard?  The man at the nursery says now is just fine (end of October). Thank you.  J., Colorado Springs, 10/26/09
A:    Spring is the best time to transplant pines.  Fall planted evergreens can dry out excessively in winter and then gradually die in spring or summer.
Q:    Hello, I planted an 8 ft. Aspen in our backyard 3 weeks ago and now I am noticing the leaves are yellowing and dropping off at a rapid pace.  I have been watering every other day.  Could this be a problem of too much water?  There are numerous Aspens around it that are flourishing.
Thanks for the help!  P. B., 7/8/09
A:    The aspen tree is going through transplant shock.  In addition, you probably are over-watering it.  Water only when the soil is just barely moist.  The soil should not stay constantly wet or soggy.
Q:    I live in East Thornton where the soil is clay. Our home faces south and I want to plant trees in the backyard (east and west side) for privacy. My problem is the areas I want to plant them are natural runoff areas for the grading on my property and don't drain particularly well. (We receive much of the drainage from our neighbors above us.) I'm trying to figure out which trees would grow best in this type of soil with the heavy moisture.  M. S., Thornton, 5/6/09
   Poplar/Cottonwood trees (be sure to get only a cottonless variety) and Willow trees like lots of water. Some large shrubs that could also be used include American Elder, Corkscrew Willow and other kinds of willows.
Q:    I live in Ontario, Canada and have a Newport Plum. It's leaves all dried out, became crisp, and fell off. There was no sign of insect infestation. What happened and will it come back this spring? The tree is about 6 years old and was very healthy. P. M., Bramalea, Ontario, Canada; 3/26/09
   You didn't mention when the leaves on the Newport Plum dried out and fell off.  If this occurred during the summer it could be an indication of root damage, insufficient water, herbicide damage, or pests that weren't detected.  If this occurred in early fall, it could also be damage from an early frost.  Only time will tell if the tree will recover.  Keep it watered well this spring.
Q:    We have a large walnut tree which has had a branch knocked by a truck.  It is now weeping a large amount of sap. What should we do, as we do not want to lose this tree?  Thank you in advance.  F. B., London, UK; 1/12/09
A:    Unfortunately, there is little you can do about the sap.  The wound should gradually heal and the sap will stop flowing.  However, if the damaged branch is now a hazard you should remove it.  Wounds are entry points for pests and disease organisms.  Examine the tree periodically for any signs of these and treat promptly when necessary.
Q:    I have a tree that hangs over my driveway that produces small non-edible berries all year round. The berries are dropping all over the driveway and yard to the point where our driveway looks painted black sometimes. Is there a way to stop the tree from producing berries or at least considerably lower production?  S. G., Orland, FL; 12/27/08
   There is a product you can spray on the tree to limit production of berries.  It is called Florel.  It must be sprayed at exactly the right time.  Read and follow the label directions precisely for effectiveness.
Q:    We are interested in planting some deciduous trees for privacy from the street. We want deciduous vs. evergreen/conifer because we do not want the driveway shaded in the winter. It is a strip of land about 15 ft wide & 30 ft long on an approximately north to south axis. We have considered aspens, because our elevation is about 8900 ft, but I'd like to consider a hardier disease-resistant species. What can you suggest & can we plant them yet this fall?  L. G., Silverthorne, 9/2/08
   In the mountains trees should be planted in spring.  Some native trees to consider are Thinleaf Alder (Alnus tenuifolia) and Rocky Mountain Birch (Betula occidentalis).  These trees grow 15 - 20' tall and about 10' wide.
Q:    I have what was sold to us as a 'fruitless' Newport Plum tree. It is approximately six years old and has been producing more and more fruit every year for the past four. How can I stop the fruit production and still not kill the tree? It is a real nuisance as it is located in the city strip between our sidewalk and the street. Thank you for any help you can offer.  J. T., Denver, 8/26/08
   You can spray the Newport Plum tree with Florel in spring to prevent fruit set.  Timing is crucial.  It won't work if you spray too early or too late.  See the label for instructions.
Q:    I have a tree that hangs over my driveway that is leaking sap. What can I do to make it stop?  J. R., Colorado Springs, 8/19/08
   If it is sap that is leaking, there isn't anything you can do.  However, the sticky substance may be "honeydew" secreted by aphids.  Spraying the tree with a strong jet of water or insecticidal soap may help.
Q:    I have 2 relatively mature trees that are producing suckers near the tree--a crab apple and a chanticleer pear. They look healthy and don't appear to be injured. What's going on and what should I do?  R. C., Lone Tree, 8/3/08
A:    Some trees are prone to producing suckers.  Others produce them when they are under stress.  The suckers should be removed while they are still small.  Keep the trees watered well and fertilize them in spring to improve overall vigor.
Q:    It is July 2008 and the leaves of two of our Autumn Blaze maples are starting to turn red and orange. Why would this be happening? We live in the northwest subs of Denver.  C. M., Wheat Ridge, 7/13/08
   Premature fall color can be a sign that a tree is under stress, often root-related stress.  Try to improve the vigor of the trees by keeping them well watered and treat any pest or disease problems promptly.  Be careful about using weed and feed products or other herbicides in areas where their roots are growing.
Q:    I have a willow bush in a place in my yard that gets a lot of water. Now some of the leaves are turning yellow. Is it getting too much water or not enough??  A., Thornton, 6/28/08
A:    If the yellowed leaves are toward the outer ends of branches and toward the top of the bush the problem is probably too little water.  On the other hand, if the yellowed leaves are toward the inner part of branches and the bottom of the bush it may be getting too much water.
Q:    I have a persimmon tree that bears plenty of fruit. The problem is that I really, really dislike persimmons. To top it off the tree creates quite a real mess! How can I stop the tree from producing fruit?  J. A., Marshall, IL; 5/13/08
   There is a product called Florel that you can spray on trees to prevent fruit set.  Correct timing of the spraying is essential, so be sure to read and follow the label's directions.
Q:    I have a 30 ft. ash tree that has had beautiful leaves until this past year. The leaves became curly. What's wrong and how do I treat it?
   Also, I read on your Q&A not to trim maple trees until after it has leaves because of the sap. I already trimmed it and it did leak sap. What now?  J. T., Colorado Springs, 4/20/08
   The ash tree's leaves probably curled due to aphids.  You should hose off the leaves with a strong jet of water this spring on a regular basis.  If that doesn't control the aphids spray the tree with an insecticidal soap solution.  Use a stronger pesticide only as a last resort.
    The maple's pruning cuts will eventually heal over and the leaking sap will stop.  The tree hasn't been harmed.
Q:    I am trying to spray my Aspens w/fungicide. It says to do at budbreak the first time. When is and what does the budbreak look like? Will there be a leaf? Our spring is very late here so I want to do it at the right time. M. T., Bend. OR; 3/13/08
   Budbreak occurs at slightly different times in spring, influenced largely by weather conditions.  In spring little nodules develop on branches.  As the weather warms up these little nodules split open and you can see the little green leaves that are forming.  This stage is called budbreak.  Do not wait for the leaves to be fully formed.
Q:    Will puncturing the bark of a trembling aspen induce black rot? Is there a way to attach a structure to an aspen without killing the tree? Please pass on any information you have regarding these matters. Thanks. B. B., Winnipeg, MB; 2/2/08
   Within the trunk of a tree are tube-like structures that transport water and nutrients up to the top of the tree and ones that transport sugars down to the roots.  If these are badly damaged by punctures the water, nutrients and sugars can't be transported and the tree will die.  In addition, puncture wounds in the trunk provide a path for disease organisms and pests to invade the trunk.  Therefore, puncturing the trunk of a tree is not recommended.
Q:    When should I trim a maple tree in the Littleton/Highlands Ranch area?  G. G., Littleton, 1/14/08
A:    You should avoid pruning maple trees in late winter or early spring.  Maples ooze sap, called "bleeding," when pruned at that time.  You can prune the maple tree after it leafs out in spring.
Q:    Do willow hybrid trees stay green year round?  I'm considering getting some to use as a fence tree.  Thanks, J., Fayetteville, GA;  12/9/07
A: No, the willow hybrid does not stay green year round.  It is a deciduous tree.
Q:    We live in Reunion - Commerce City, and have just had 2 clumps of aspens planted along our east-west fenceline between our home and our neighbors.  A very reputable nursery planted them for us at the end of September.  The first 3 weeks were met by very windy and warm weather - the wind blew half of the leaves off and now the remaining leaves have turned dark green, black, crispy, and are falling off.  I fertilized lightly with a root stimulator and good water about the third week, and they have had good water three times a week.  They have not been overwatered.  My father-in-law says they may be "stressed out" from being planted and subject to those strong winds we had a month ago.  Was I right or wrong to lightly fertilize? Is it normal for them to have black leaves that crisp up and fall off?  The branches of the trees are bendable, so I know they are not dead.  How normal is this 6 weeks after planting?  D. C., Commerce City, 10/17/07
   It is common for newly planted trees and shrubs to go through "transplant shock."  The root system needs a few weeks to adjust after being disturbed when planted.  The roots will struggle to provide enough moisture to the rest of the tree.  Drying conditions such as high temperatures or windy weather make the problem worse and can lead to leaf drop, brown edges, etc. 
    Newly planted trees and shrubs should not be fertilized.  The fertilizer promotes growth of additional leaves at a time when the roots are already struggling to support the moisture needs of the existing leaves.
    Continue to water the trees regularly.  During winter you should water them about twice a month if there is little or no snow.  Water early in the day when the ground isn't frozen.
    When the leaves fall this autumn be sure to rake them up and get rid of them.  Disease organisms and pests can over-winter in fallen leaves and then attack the trees in spring.
Q:    I have two Aspens along one side of my house that are growing too close to the house.  One is about 6" thick, the second one is 4".  I want to transplant them to a more open area in the front.  I will be doing it myself.  Is this a do-able job?  What time of year would be best?  What reaction from the trees can I expect?  Thanks!  S. M., Denver, 10/10/07
A:    Transplanting such large trees will be a challenge.  Their root systems are very large and only a small portion can be dug up.  Early spring is the best time to transplant the trees.  Water them well a few days prior to digging them up and keep them well watered after planting them.  Unfortunately, you may lose them, but it is worth trying since they need to be moved from their current location.
Q:    It is mid September and I have received permission to dig trees in an area that is about to be developed. First question is what is the proper way to dig trees for transplanting? The area has Spruce and Aspen and I would like to transplant them to San Luis Valley where I own property. Is mid September to early to dig up these types of trees and what care is needed so they survive after transplanting to them to this area? Seems like a waste to let these trees be destroyed and I very much would like to plant some on a treeless property! Please help with digging and transplanting information.  P. W., Fountain, 9/11/07
   Planttalk Colorado has two articles that explain how to dig up and transplant a tree.  Please see  After reading it click on message number 1711 (near the bottom of the page) for more information.  You may be able to transplant the aspens successfully in fall, but the spruce trees will be a challenge.  I suggest that you buy a product called Wiltpruf to spray on any conifers you transplant.  It helps the trees retain moisture during winter.  Small trees are more likely to survive being transplanted than large trees.
Q:    I just pruned a large broken branch from my Aspen tree. The branch was about 2" in diameter.  Would it be a good idea to spray the cut spot with one of those "tar" type petroleum based products for protection?  J. O., Thornton, 8/27/07
A:    Sealants generally are no longer recommended on pruning cuts.  The tree will form a callous over the wound for protection.
Q:    I have two beautiful Linden trees that border my house in the space between the sidewalk and street here in Denver.  One of the trees has severe browning of the leaves every summer.  It is now mid-August but the half that faces North looks miserable.  Is the tree diseased?  P. S., Denver, 8/21/07
   I suspect the leaf browning is due to damage or disease affecting the roots or trunk of the tree.  It might be worthwhile to contact a tree service company to examine the tree.  They can diagnose the problem and suggest appropriate treatments.
Q:    I have a honeylocust tree newly planted last September in a sodded area that started to leaf but now the leaves are smaller than they should be, yellowish and dry.  We are near Elizabeth, CO, elevation 6600 ft.  The soil is clay/sand mix.  The soil seems moist but not overly wet, no evidence of insects, bark has what looks like scratches on it. We had a light frost about 10 days ago.  What can I do to keep my tree alive?  C. D., Elizabeth, 6/12/07
A:    Honeylocust trees in much of Colorado's Front Range are doing poorly this year.  Our weather this winter may be a factor.  All you can do at this point is keep the tree watered well (but not over-watered) and perhaps fertilize it lightly.  If the sodded area it is planted in has been fertilized do not add additional fertilizer.  Also, you should avoid using Weed 'n Feed products on the sodded area.  They can harm the tree.  While the tree is young be sure to wrap the trunk with tree wrap from late fall to early spring to avoid sunscald.  The scratches could be caused by cats, they may be cracks caused by sunscald, or if you see gnawed areas they may be due to voles.  A stressed tree is more likely to be attacked by pests and diseases.  Inspect the tree regularly and treat promptly if you see signs of these.
Q:    I live at 7500 ft. outside Monument, CO.  I had someone plant in November 2006 20 Pinon Pine trees in my yard.  I already had some Pinons and Ponderosa pines that were doing great.  However, the newly planted Pinons are turning brown.  They were in snow from late November through March 2007.  What can I do to save them? S. G., Monument, 4/2/07
A:    Lots of pines are showing signs of damage from this winter's weather.  Unfortunately, there is little you can do to help them.  As the weather warms up check the soil regularly and water the trees when the soil becomes dry.  Water thoroughly and allow the soil to dry out before watering again.  Pines don't like soggy soil.  If you need to replace any of the trees I suggest that you not do so in the heat of summer or in fall.  Fall-planted conifers are prone to winter damage and die-off.
Q:    Will pruning a maple tree in January kill the tree?  C. S., Scottsville, KY; 3/27/07
A:    Pruning a maple tree in January is not recommended, but it won't kill the tree unless done really badly (too much of the tree removed at once, jagged cuts, torn bark, etc.)
Q:    Do you have any advice about what trees to plant in a small backyard with not very much width room?  N. S., Denver, 3/26/07
   Some small trees that don't grow too wide include these:
      Chanticleer Pear (Pyrus calleryana 'Chanticleer') 25' x 15' -- fruitless   
      Newport Plum (Prunus cerasifera 'Newport') 25' x 15' - fruitless
      Canadian Cherry (Prunus virginiana 'Shubert') 30' x 20'
Q:    I have a large autumn blaze maple in my yard that just started oozing sap, dripping down the trunk, and off branches. I do not recall this happening in the past.  Could there be a problem or just a natural happening?  K. R., Loveland, 3/5/07
A:    I suspect the maple tree has frost cracks that are oozing sap.  This is a fairly common occurrence when we have freeze/thaw cycles.  Cracks in the bark are created when it freezes.  Then, when it warms up a bit the sap seeps through the cracks. 
Q:    The tree nursery said it was okay to plant a ponderosa pine in the fall, so we did.  I watered it after two hours, maybe too much.  It started looking yellow after five hours.  What can I do?  M. N., Castle Rock, 11/10/06
    When you plant trees they should be watered deeply and immediately.  I doubt you harmed the tree by watering it.  The tree is probably going through transplant shock while it adjusts to being planted and to being in a new home.  You will need to water it during winter.  Check the soil frequently.  If it is dry, water the tree early in the day to prevent freeze damage.  It would also be a good idea to spray it with WiltPruf, a product that will help prevent moisture loss.  Evergreens can dry out in winter and then die.
Q:    How do I know when to trim back shrubs and trees?  I live in Peyton, CO, and am not as up to date with tree and shrub types in my garden.  Thank you.  J. M., Peyton, 9/30/06
    Most deciduous trees (trees that lose their leaves) are usually pruned in late winter or early spring before they leaf out.  Maple, birch and walnut trees tend to ooze sap if pruned when dormant, so they are usually pruned in spring after they leaf out.  Avoid pruning in late summer.  Evergreen trees can be pruned anytime when needed.
    Flowering shrubs such as lilacs generally are pruned as soon as they finish blooming.  Non-flowering shrubs are pruned in late winter or early spring.  Avoid pruning them in late summer. 
Q:    We live in Morrison, CO, and have 2 young (4-5 year old) corkscrew willow trees that are growing and healthy.  However, this year we have noticed the trees are full of small bees.  Do we need to worry about damage the bees might do to the trees?  S. W., Morrison, 9/7/06
  Willow catkins produce nectar and pollen that attract bees.  Also, if the trees have aphids, which produce a sweet sticky substance called honeydew, the bees are attracted to it.  The bees won't harm the trees. 
Q:    We live in Elizabeth, Colorado, and have many Ponderosa Pines, which we love.  However, we would like to plant a different kind of tree in the front area (we live on 2 acres).  What types of trees would be good for our area, as we are a little higher in elevation?  Can we plant them in the fall?  Thanks for the information!  K. B., Elizabeth, 9/6/06
   Yes, you can plant deciduous trees in the fall.  It is a good time to plant almost everything except evergreen trees.  Evergreens planted in fall lose moisture through their needles in winter and dry out.  This often results in their death.
    If you want shade trees, Ash trees are a good choice.  Hackberry, Catalpa, Linden, Oak and Cottonless Cottonwood are also popular.  Avoid Aspens -- they are too prone to pests, diseases and suckers.
    Smaller trees that do well are Crabapple, Hawthorn and Callery Pear.  They have blossoms in spring.
Q:    What are the planting requirements for an ash tree? For example, how far from a structure should one be planted, how large will it grow and should it be in part shade or full sun?  Thank you!  C. B., Aurora, 8/24/06
    Ash trees perform best when planted in full sun.  They prefer regular watering.  Most grow 40 - 60' tall and 20 - 40' wide.  Therefore, the tree could be planted about 20' from a structure.
Q:    Hello, I live in Canon City, CO, and I want to plant a Crimson King Maple. Will it grow in this area?  Send me an idea of what Maples would do good here.  Please let me know. Thanks , L. A., Canon City, 7/25/06
    'Crimson King' Maple is one of the cultivars recommended for Colorado.  It should grow in your area.  Some other recommended cultivars include 'Deborah,' 'Emerald Queen,' and 'Royal Red.'
Q:    We are wondering if cypress trees will grow in our Lakewood northern exposure landscaping?  I. F., Lakewood, 7/22/06
    Bald cypress (Taxodium distichum) trees are a deciduous conifer that grows here.
Q:    We were working on some major overhaul of the landscape in the front yard and hit the roots of the aspen tree with the tractor blade.  It ripped up a root and that tore the bark in the front of the tree.  My brother-in- law says we killed the tree.  Is that correct?  T., Montrose, 7/9/06
A:    The damage to the bark of the aspen tree, if severe enough, can cause the tree to die.
Q:    Hi,  I have some sort of growth on my scrub oak.  They are fuzzy spheres that are a lime yellow color to red.  They are on the underside of the leaves and are on quite a few of my oaks.  What is this and what do I do about it if anything?  Thank you,  B. B., Colorado Springs, 7/5/06
A:    The spheres on the oak tree leaves are probably galls produced by gall wasps.  They are very common in Colorado.  Usually control isn't necessary.  Insecticides can be sprayed in late fall or winter when adults emerge and are laying eggs.
Q:    I have a Newport Plum tree in my front yard that is about 10 years old.  I have been fighting the growth of little shoots all through my front lawn and a neighboring rock garden -- probably a 25-30 foot radius around the tree.  I am afraid I will have to destroy the tree, but I am not sure this will solve the problem if it is coming from the roots of the tree.  Any suggestions?  S. G., Posen, MI; 5/16/06
    There is a product called Sucker Stopper you can spray on the shoots of the Newport Plum to kill them.  Be sure to read and follow label instructions.  Avoid getting this product on the lawn.
Q:    Buds on my Patmore Ash  and Honey Locust recently froze.  Will they just come back automatically or should I do something special to help trees?  I am in Lakewood, Green Mountain area.  C. S., Lakewood, 5/3/06
   If the trees are healthy they should recover and produce a new set of leaves.  Keep them well watered.  You can also apply a bit of fertilizer to promote growth.
Q:    We have just moved here and have a large lot to landscape. We live in Falcon, which is windy, and want a windbreak of trees. Our soil has some clay and we are wondering whether a Ponderosa or an Austrian Pine will do better in high winds. Thank you. K. B., Falcon, 4/12/06
A:     Both Ponderosa and Austrian pines perform well as windbreaks.  The Colorado State Forest Service rates Ponderosa pines as "excellent" windbreaks and Austrian pines as "good" windbreaks.
Q:   I would like any suggestions you could give me regarding trees for my yard.  We recently moved into a new house here in Colorado Springs, and want to plant two trees in the backyard.  We would like something that grows to it's surroundings, and has color. The area for the trees is 8 feet by 8 feet.  The areas are in the corners of the back yard and they receive the west sun in the afternoon.  I came out 4 feet from the fence with rock, and then made the areas for the trees.  The rest of the yard has grass.  Any ideas?  Thank you for your help.  S. M., Colorado Springs, 2/15/06
   It appears you have a fairly limited area for the trees.  The following trees are suitable for smaller spaces:
    Newport Plum (Prunus cerasifera 'Newport'): 25' tall, pinkish-white flowers, maroon foliage.
    Spring Snow Crabapple (Malus): 20' tall, white blooms in spring, a fruitless variety.
    Centurion Crabapple (Malus): 25' tall, rosy red blooms and fruit
    Chanticleer Pear (Pyrus calleryana 'Chanticleer'): 25' tall, white blooms in spring, maroon fall color.
Q:   I have a large, beautiful walnut tree in my back yard that has made the yard uninhabitable!  It is a haven for squirrels who, from April through October, sit up there nibbling a few bites off a seed and hurling it down, sometimes from two or three stories up.  The heavy nuts become harmful projectiles!  Not only that, the partly chewed nuts, still in their green hulls, become sharp litter all over the lawn, making barefoot walking next to impossible!  I'm also told the decomposing shells inhibit other things to grow.
   We had a tree collar put up and the squirrels hang out on it!  I love the tree but I have  considered cutting it down because I want a back yard I can be in. Someone suggested an understory net to catch the nuts, which also sounds problematic. Is there anyway to keep the tree from setting nuts?  Any other ideas?
      Thank you so much for any advice you can give me!  L. G., Denver, 2/5/06
A:     I'm sorry, but I don't have any solutions for the problems with the walnut tree.  A net is a possibility, but I foresee putting it up and maintenance as issues.  While there is a product available to limit fruit-set on fruit trees, I am not familiar with anything for nut trees.
Q:    How do we trim years old corkscrew willow trees?  We just bought a house with two in the front that have never been pruned.  Please advise.  B. K., Livingston, CA; 1/4//06
A:    You can shape the corkscrew willow trees, removing no more than one third of the branches annually.  Topping trees (cutting off the ends of branches to shorten the height of the tree) is not recommended because it results in weak new growth that is prone to breaking.  Instead, thin out problem branches.  Do not cut branches flush with the trunk.  Cut them just beyond the small bulge, called the branch collar, that is near the trunk.   If the branches are very large or if the trees are tall, you might want to consult an arborist.
Q:    I live in Chicago and we have a Horse Chestnut tree that needs to be trimmed back (no major branches).  What is the best time of the year to do this?  Is there a time or temperature to avoid (like middle of winter)?  Besides the obvious concerns, we had a hot/dry summer, and December has been pretty cold here so far, so I don't want to cause any more stress to the tree if we shouldn't be trimming some of it's branches now.  Thanks!  S. P., Chicago, IL; 12/7/05
A:   Early spring, just before a tree's leaves open, is a good time to do pruning.
Q:    I live in Ohio and I want to grow a Pinus aristata in my yard. I have failed twice.  I put it on a bank and watered it and mulched it, also. Will this tree grow in Ohio?  I know its natural habitat is high {10,000}feet and higher, but will it grow at lower sea level?  They seem to do OK during the first year and the next spring the needles start turning brown and it dies. Help!!!  J. W., Youngstown, OH; 9/29/05
A:     Bristlecone pine (Pinus aristata) will grow in USDA hardiness zones 3 - 7.  You live in zone 6, so it should survive there unless there are problems with the soil.  Pine trees need good drainage.  They require little water once established.  Do not plant the trees in summer when the weather is hot.  Also, do not plant them in fall.  Evergreens planted in fall tend to dry out excessively during winter and then die in spring.  Plant them in early spring.  Keep the soil moist, not wet, while they take root and gradually reduce watering.  Winter watering when the soil isn't frozen may help the trees survive dry winters.
Q:    I just purchased a new home in Aurora, and I have to provide my own landscape.   I would like to plant some trees along my fence line that's open to the street for privacy.  However, I am not sure what trees to plant, and is it wise to plant these trees in the fall season?  Please keep cost in mind. I. M., Aurora, 8/29/05
A:     Spring is the best time to plant trees.  Fall is the second best time.  Evergreen trees should be planted in spring.  Because they don't have an established root system, winter weather can dry them out and lead to their death.  You didn't mention how much space you have for the trees, but I expect not a lot if you have a typical yard.  Because you want the trees to provide privacy evergreens would be best.  Limber pine (Pinus flexilis) grows 15 - 20' wide.  Rocky Mountain Juniper cultivars such as 'Cologreen,' 'Wichita Blue' and 'Moonglow' grow 15 - 20' tall and stay narrow.
Q:    Could you please recommend some possible trees/bushes that may fit into my back yard?  I live in Westminster, CO, and am in the process of landscaping my back yard.  The area is not very big, so I am trying to be careful about the type of plants that I choose.  I am looking for perhaps a tree that would provide some shade or a bush for privacy.  The area I would like to plant it in is between my porch and fence, and about 2 1/2 ft by 2 1/2 ft, and gets full to partial sun.  M. F., Westminster, 8/16/05
    It sounds like the area for planting a tree is very small.  A columnar tree or shrub may work best.  The following are evergreens and would provide privacy.
      Fastigiata Scotch Pine (Pinus sylvestris 'Fastigiata'): 20' tall, 3 - 4' wide
      Skyrocket Juniper (Juniperus virginiana 'Skyrocket'): 15' tall, 3 - 4' wide
      Medora Rocky Mountain Juniper (Juniperus scopulorum 'Medora'): 10 - 15' high, 3 - 5' wide
Q:    We have a huge, old cottonwood tree that is the dirtiest tree we've ever seen.  Can anything be done to stop the tree from producing cotton? 
We won't cut the tree down mainly because it is too expensive (over $2,500), but it is making our lives miserable because of all the work cleaning up its mess.  D. S.; Sterling Heights, MI; 7/31/05
A:   I understand that Florel can limit the production of cotton on cottonwood trees.  The timing of the application is the key to its success, so read and follow label instructions carefully.  The product is sprayed on the tree.  Because the tree is "huge" spraying may be a challenge.
Q:    We have a small Colorado blue spruce in our back yard that we got as a seedling about 5 years ago.  It's now about 3 feet tall & we want to transplant it into the center of the yard where it will have more room to spread out.  We have somewhat sandy soil.  It is okay to move it this time of year?  B. D., Colorado Springs, 7/4/05
A:   Summer is not a good time to transplant trees.  Tree roots get damaged in the process and have difficulty absorbing sufficient water for the tree.  If you don't mind waiting, spring is actually the best time to transplant the tree. 
Q:    We have had the trees in our mobile home park trimmed/deadwood cut out, etc., and there are quite a few that have sap dripping from the cut areas.  What can we do to stop the dripping, etc?  K., Albuquerque, NM; 6/20/05
A:    I am not aware of anything that can be done to stop the dripping sap.  Gradually the trees will form a protective barrier over the wounds and sap flow should gradually cease.
Q:    I live in California and just bought a half acre in Leadville, Colorado. What trees could I plant that with some TLC could survive at that high altitude. Any size is ok.  N. R., San Jose, CA; 5/22/05
   Some trees that grow at elevations up to 10,500 feet include these:
        Engelmann spruce (Picea engelmanni)
        Bristlecone pine (Pinus aristata)
        Limber pine (Pinus flexilis)
        Subalpine fir (Abies lasiocarpa)
    The growing period is very short at Leadville's altitude.  The trees should be planted as soon as the ground isn't frozen so the roots can become established before the ground freezes again.
Q:    Hello, I was wondering if you could help me.  My mother loves to garden and being the good daughter that I am I would like to get her some trees. Unfortunately I don't have to a clue to what would have the best survival rate for Pueblo West, CO.  I was wondering if the Norway Spruce, Colorado Blue Spruce or White Pine would be good choices. They would probably be small seedlings. It can become very hot and very windy in Pueblo West.  There isn't much rainfall either. I'd really appreciate any advice. Thanks!  M. Lincoln, NE; 2/26/05
A:     Some trees that should do well in Pueblo West include Pinon Pine (Pinus edulis), Austrian Pine (Pinus nigra) and Bur Oak (Quercus macrocarpa).  Colorado Blue Spruce would also do well, but it requires more water than the pines or oak.
Q:    I have an evergreen tree probably 40 ft high with a trunk that is 1 1-2 ft round.  It is starting to lose its needles from the bottom up.  It is getting pretty bad.  What can I do to revive this tree -- fertilizer spikes, tilling the ground, what?  J. H., Horace, ND; 2/14/05
A:     Browning of evergreen needles and needle drop can be caused by several things.  Older needles on evergreen trees turn brown in fall and drop.  The species of the tree determines just when this will occur.  The inner needles are mainly involved in this process.  Too much moisture and poor drainage can cause needles to brown and drop.  A symptom of this problem is that browning moves from bottom to top and from the inside to the outer edges of the branches.  Winter injury due to desiccation can cause browning.  Pests such as mites, aphids, etc. can damage the tree.  Inspect the tree with a hand lens for these.  Do not till the ground under the tree.  That would damage the tree's roots.  Wait until spring to fertilize the tree.
Q:    Can you tell me what, if any, kind of palm and banana trees are compatible with our Colorado conditions?  T. W., Aurora, 1/14/05
A:     I did a search on the Internet to see if any palm or banana trees were suited to Zone 5.  I did not find any palm trees, but I did find information about a banana.  Japanese Fiber Banana (Musa basjoo) can grow in Zone 5 if protected.  It needs to be heavily mulched (One foot was suggested).  A south-facing spot near a structure such as a wall is a good site.  The fruit isn't edible.  It is grown for its tropical appearance.  It is likely to die back in winter but will resprout in spring if mulched well.

Q:    I'm in Denver and have a living Norwegian Pine.   I've been given different advice about planting it outside.  Can you tell me if will it grow well in this climate or if I should retain it as a house plant?  K. C., Denver, 1/3/05
A:     The Norwegian Pine can be planted outside -- but not now.  Wait until spring to plant it.  Newly planted evergreens tend to dry out in Colorado's winter weather and then die.

Q:    I live in Grand Junction, Colorado.  A local landscaper stated that he can plant established trees and shrubs well into the winter months of December and January.  Is this an acceptable time to plant these types of plants? Thank you.  R. W., Grand Junction, 12/7/04
A:    Winter is not considered a good time to plant in Colorado.  Spring is the best time.  Early fall (until mid October) is considered the second best time to plant.  However, evergreens should not be planted in fall. The plants lose moisture through their needles and their young root systems can't provide sufficient moisture in winter.

Q:    We have two magnificent weeping willows around 70' high.  These two trees are the focal points in lovely garden areas but some pruning/topping problems have come up.  The trees were topped about ten years ago prior to our acquisition of the property.  As a result they branched.  Last fall each tree lost 2 very large limbs.  They were recently pruned up to 35' but we are now wondering if they should be topped again and if that can be done without further branching.  Or, should we simply thin the upper areas?  I recently read an article that strongly recommended against tree topping.  We're particularly concerned about why both trees lost two large (24" dia) limbs at about the same time.  One particularly has a big gap in the foliage that will probably take years to fill in.  Your opinion on the subject will be greatly appreciated.  S. B., Fairfield, CA; 11/9/04
A:     As you have read, topping trees is not recommended.  It causes trees to produce multiple new branches.  Unfortunately, this new growth often is weak and unnatural looking.  In addition, topped trees are prone to disease and insect problems due to the many, large cuts.  Thinning is much preferred.

Q:   I live on the south side of Colorado Springs and I really would love to grow a horse chestnut tree in my front yard. I did some research on the particular kind of tree. I found out that it likes clay soil. Since we are surrounded with it, it should do well here. One the other side, I hardly ever see horse chestnut trees here.  Could you please tell me some more about it?  Thank you. A. M., Colorado Springs, 9/30/04
A:     Common horsechestnut (Aesculus hippocastanum) is a large tree that grows 50' high and 40' wide.  It does well in full sun or part shade.  It prefers moist soil.  It has white flowers in spring and produces fruit, which can be a nuisance to clean up.  The roots can be invasive.  It does perform well here.

Q:    Looking for recommendations for a tree reddish in color that will grow in height 10 to 20 feet with 10 to 15 foot canopy.  The tree location will be approx. 10-15 feet from the front corner of the east side of  the house and the same distance from a stone walkway in the Denver Hilltop area. Can you provide a list of some recommendations?  J. H., Denver, 9/7/04
   Some small, reddish or purple leafed trees include these:
        Newport Plum (Prunus cerasifera 'Newport')
        Mt. St. Helens Plum (Prunus cerasifera 'Mt. St. Helens')
        Double-Flowering Plum (Prunus triloba)
        Purple Prince Crabapple (Malus 'Purple Prince')
        Royalty Crabapple (Malus 'Royalty')

Q:    I would like to plant a European Mountain Ash on the north side of a large blue spruce.  If I am prepared to take heroic measures in soil amendment--to make it more well-drained and pH balanced--do I need to be concerned about which variety will fare best?  I prefer the Sorbus Aucuparia 'Cardinal Royal' because of the berry color, but I've been told that 'Black Hawk' is hardier and more sun scald resistant. Would that mean 'Black Hawk' is more fire blight resistant, also? Thanks!  J. M., Fort Collins, 9/4/04
A:     European Mountain Ash (Sorbus aucuparia) needs well-drained soil and prefers acid soil, so you will need to prepare the planting site well.  This type of tree is very prone to problems such as canker and borer when stressed.  Compacted soil, heavy clay soil and alkaline soil will stress it.  Black Hawk is more resistant to sun-scald.  Sun-scald wounds stress a tree, making it more susceptible to pests and diseases, including fire blight.  Therefore, it might be a better choice.

Q:    We live in Aberdeen, S. D.  Four years ago the county extension planted a tree claim of lilac bushes, which are doing great, and cottonless cottonwoods. We transplanted them 2 years ago and this year we lost over half of them (transplanted 30). Now we have about the same amount of evergreens to move but we don't know the best time to move them. Could you give us some advice?  M. M., Aberdeen, S. D.; 7/21/04
A:     Early spring is the best time to transplant evergreens.  Do not move them in fall.  The root systems, which are disturbed/damaged during moving, can't supply enough moisture during winter and they will dry out too much.  By spring they would begin to die off.  During the hot days of summer is also a poor time to move them for the same reason.

Q:    How do I properly prune scotch pine trees?  They are currently in the candlestick phase.  R., Greeley, 5/29/04
A:     To prune pine trees, snap off a portion of the candles - usually about a third or half of the candle.  Snapping them off, rather than cutting them off with pruners, is advised to prevent edges from browning.

Q:    I have a newly planted Ponderosa Pine, approximately 12 ft. tall. on an elevated berm, approximately 24."  It was planted last fall, and I do have it on a drip system.  It also gets a little overflow from the grass sprinkler.  I am getting some yellowing.  Any ideas?  I did give it a root stimulator early in the spring.  B. F., Loveland, 5/8/04
   Too much or too little watering can cause yellowing, so it can be tricky to determine if you need to water more or less.  If you did not water the tree during winter, it may be showing the effects of too little water.  The root system of an evergreen tree that is planted in the fall often struggles to meet the tree's water needs in winter. 
    If you have been running your sprinklers and the tree is just starting to yellow, it may be getting too much water -- especially since it is on a drip system and gets water from the grass sprinkler.  Pines need good drainage and only a limited amount of water once they are established (about a year after planting).  You may need to adjust the amount of water the tree gets from your irrigation system.

Q:    Yikes!  We live at 8,600 feet just outside of Mancos, CO.  We shift from drought to snow in the blink of an eye - well maybe from year to year.  We have fields full of pinion, some cedars, Ponderosa Pine, and have had a little success cultivating aspens.  But my wife misses her big flowering trees.  Are there any medium to larger flowering trees that would survive the summers and winters in this high sunshine, sometimes moist, sometimes heavy snow area?  G. Mancos, 4/28/04
A:    Unfortunately, the lists of trees for high elevations I have available do not include any flowering trees for elevations above 8500 feet.  With protection -- and luck -- apple trees such as 'Lodi' or 'Haralson,' some crabapples and Shubert Chokecherry (Prunus virginiana 'Shubert') might survive.  They are listed as hardy to 8500 feet.

Q:    Just wanted to get some recommendations for a small tree to fill a spot in my backyard.  I already have a Austrian pine about 25 ft. tall and I would like something colorful to compliment it.  PS - I don't want anything that has fruit on it.  Thanks  A. J., Loveland, 4/20/04
   The following are some small trees that would be colorful during some seasons:
Cleveland Select Callery Pear (Pyrus calleryana 'Cleveland Select') -- This tree is non-fruiting, has white blossoms in spring and has fall color.
Spring Snow Flowering Crabapple (Malus 'Spring Snow') -- This tree is non-fruiting and has white flowers.  It has some fall color.
Newport Plum (Prunus x cerasifera 'Newport') -- This tree has pink flowers, purple foliage and little, if any, fruit.

Q:    What location considerations would you use if you wanted to plant an eastern red bud tree and Japanese maple in our climate?  Are there any species that are more hardy in Colorado.  Live in Brighton.  B. T., Brighton, 4/19/04
    Eastern Redbud (Cercis canadensis) trees perform best in full sun, although they tolerate partial shade.  A spot sheltered by structures or other plants is preferred.  They require good drainage.  Therefore, you should amend the soil with compost before planting.  Avoid using products containing cow manure because the high level of salt will damage the tree.  Eastern Redbud trees prefer moist, but not soggy, soil.
    Japanese Maple (Acer palmatum) trees require filtered shade.  A northern or eastern exposure is best.  They need shelter provided by structures or other plants.  They like moist, well-drained soil and are harmed by high levels of salt in the soil.  Hardiness can be a problem here.  Unfortunately, I am not familiar with which species of these trees are most hardy.  Be sure to check plant labels for this information when shopping.

Q:    Can we grow Magnolia Trees in Lakewood, Colorado?  K. B., Thornton, 3/31/04
   There are some types of Magnolia trees/shrubs that can be grown in Colorado, but they are not the large, stately trees associated with the South and other warm climate areas.  They require a sheltered location, away from wind and sun.  An eastern exposure works well.  They like moist, well-drained soil and may have problems in heavy clay soil.  Late spring snow and spring frosts may damage flowers.  Some types for Colorado include these:
    Saucer Magnolia (Magnolia x soulangiana) 15 - 20 ft. tall
    Star Magnolia (M. stellata) 10 - 15 ft. tall
    Hybrid Magnolia (M. x loebneri) 15 - 20 ft. tall.  Look for 'Ballerina,' 'Merrill' or 'Leonard Messel.'

Q:    I live in zone 6.  We have a 20+ year old corkscrew willow.  Some of the branches did not get leaves last summer and appeared dead.  We have not trimmed/pruned this tree that I know of -- ever.  How and when do we do this?
It is a beautiful tree and it breaks our hearts to think we could lose it.  Thank you, D. L., Gardnerville, NV; 3/7/04
A:    Unfortunately, corkscrew willow trees are short-lived.  Try to keep the tree as healthy as possible by providing plenty of water.  Check the branches carefully for signs of pests that could cause the tree to decline in health.  Prune off dead branches.  Hopefully it will last a bit longer.

Q:    I planted a bristlecone pine in my front yard two years ago (south facing, full sun).  In general, the tree seems healthy with a few inches of new growth each year; however, the ends of the bottom branches are browning and dying.  I've examined the soil under the tree and it always seems moist, but it also seems like the tree likes to be watered from the top during the summer -- this seems to slow/recover some of the brownish needles.  I think that the soil is wet enough, but all signs point to the tree wanting more water.  Is the full sun too much for the tree regardless of the watering frequency?  C. H., Fort Collins, 2/18/04
A:    Bristlecone pines require full sun, so the amount of sunlight is not causing the browning.  This tree does best in well-drained soil.  If the soil is constantly moist the tree will probably die.  The tree should be watered deeply.  Apply water throughout the root zone -- a distance equivalent to the height of the tree, as a minimum. Then, allow the soil to dry out before watering it again.  Hose off the tree with a jet of water to remove dust and pests periodically.

Q:   I planted a blue spruce in May 2002 and it survived the drought pretty much intact.  However, the tips of some branches throughout are bare and brown.  I deep root watered two weeks ago.  Is the tree indicating the need for additional water?  How often should it be watered?  Any advice is appreciated. thank you.  C. F., Denver, 10/16/03
A:   During spring, summer and fall you should provide about 10 gallons of water per inch of the tree trunk's diameter weekly.  For example, if the trunk is two inches in diameter the tree should receive twenty gallons of water.  Be sure to water the tree occasionally during winter if we get little snow.  Water early in the day when the ground isn't frozen.  There also are sprays, such as Wilt-pruf, that can help the tree to retain moisture during winter.

Q:    I have a very large tree in my back yard, and I am not sure if it is an oak or maple.  My question is: Why would it be loosing its leaves already?  Every time we get a wind or wind gust it drops more leaves. Can you help?  L. W., Lakewood, 7/1/03
A:   Leaf drop can be caused by a number of things.  Be sure that the tree is getting plenty of water.  Damage from the drought is a possible factor, especially with large trees.  Trees under stress from disease, insects or other unfavorable conditions sometimes drop their leaves.  Some trees will drop leaves as newer growth shades older, interior branches.

Q:    I planted a corkscrew willow this spring. Why now, 2 months later, is it losing it's leaves during our first hot spell?  It get regular watering and looked fine until this hot spell.  R. R., The Dalles, Oregon; 7/1/03
A:    Often the root system of newly planted trees cannot adequately provide the moisture needed in hot weather.  Continue to water the tree regularly.  Willows like plenty of water.  Also, spray the tree with water on hot days to provide additional moisture.  Do not fertilize the tree.  You don't want to encourage canopy growth while the root structure is limited in size and vigor.

Q:    I live in Woodland Hills, Utah, at 6,000ft elevation.  I have Aspen trees in the front yard that are beginning to block the view of the valley below.  They start blocking the view when they get about 15-20 feet high. What is the correct method to "top off" the trees without hurting them or making them look like they've been hacked off?  Thank you.  R. P., Woodland Hills, UT; 5/27/03
A:    Unfortunately trees cannot be topped off without hurting them or making them look like they've been hacked off.  There are two ways you can try to maintain some of the view.  You can thin the canopy of the trees by removing some of the branches.  Also, you can remove some of the trees.

Q:    Can you tell me if a Cleveland Pear would be a good tree for my front yard space of about 20 ft. wide? Also is it susceptible to fire blight or other diseases?  V. V., Boulder, 5/21/03
A:    Cleveland Pear would probably be a good tree for your front yard.  This tree, which is also known as Chanticleer Pear, grows to a height of 25 - 30 feet and a width of about 20 feet.  It requires full sun.  It is resistant to fire blight and other diseases and pests.

Q:    We are planning to install a drip or mini-spray irrigation system in an area that contains several established Aspen trees.  The "outlets" for these systems, as I understand it, are available in terms of gallons per hour.  What are your recommendations for the weekly water requirements for Aspens in these terms here in Colorado Springs?  Thank you for any assistance you may be able to provide.  R. B., Colorado Springs, 5/9/03
A:    Recent guidelines recommend the following watering schedule for April through September for established trees.
       Small trees (1 - 3" diameter): 10 gallons per inch of trunk diameter weekly
       Medium trees (4 - 8" diameter): 10 gallons per inch of trunk diameter three times per month
       Large trees (9" diameter and up): 15 gallons per inch of trunk diameter twice per month.
   Keep in mind that a tree's root system spreads out to a width that is 2 - 3 times wider than the tree's height.  Water should be applied throughout this zone, not just around the trunk.  You can reduce the amount of water applied by the drip system if the trees receive water from other sources such as the lawn sprinkler.

Q:    Hi, We have an emerald green arborvitae. It was planted last year. During the winter, the tree was getting brown and now is better. But still the edges of the leaves are brown. We asked some people.  Some told us it was burnt by the afternoon sun; some said we watered it too much. The tree is facing South.  We watered it once/month in winter, and twice/week now. Should we move the tree?
Also, our tree is not growing upwards, the top of the tree looks like it's spread out, and could not hold itself up.  How should we prune it? Thanks.  V., Longmont, 5/6/03
A:    Arborvitae trees and shrubs need shade or partial shade (no afternoon sun).  You should move it from its current south-facing location.  They are easily burned by the sun and dry winds, especially during winter.  They prefer plenty of water.  You were wise to water your tree once a month during winter.  The top of the tree probably sustained damage from heavy snows.  I suggest that you wait at least a month to see if the branches return to a more upright position rather than pruning them.  You might also try tying them into place temporarily next winter to avoid snow damage.

Q:    I am searching for a good type of tree for my area. Something sturdy, semi-fast growing and disease resistant.  K., Englewood, 3/11/03
A:     Some popular shade trees include these:
       Green Ash (Fraxinus pennsylvanica) - may have problems with ash sawfly or ash-lilac borer; does well in drier conditions
       Hackberry (Celtis occidentalis) - very drought resistant, may get harmless small bumps on the leaves called nipple gall
       Littleleaf Linden (Tilia cordata) 'Greenspire' or 'Glenleven' - attracts bees when in bloom, must protect trunk from sunscald in winter, likes regular watering
       Norway Maple (Acer platanoides) 'Deborah' or 'Emerald Queen' - likes regular watering.

Q:    I have a seventy foot white alder tree in my back yard. What is the best way to trim it?  I know it is to be trimmed in the summer. Can I top the tree and take off forty feet?  J. R., Elk Grove, CA; 1/26/03
A:    Trees that lose their leaves (deciduous trees) may be pruned in late winter or early spring when the tree is almost ready to leaf out or in midsummer after growth has slowed.  Topping trees is not recommended because it weakens the tree and can even shorten its life.  Instead, the crown should be thinned by removing selected branches.  Good candidates for removal are branches with narrow, V-shaped crotches, weak and dead branches, branches that interfere with or rub against others, and ones that are growing too low, too close to structures, etc.  No more than one third of the branches should be removed annually.  Trimming a tree of this size can be dangerous, and if it is not done properly can result in serious health problems for the tree.  You might want to look into hiring a reputable tree service for such a major task.

Q:    I have some evergreen trees that I need to trim down.  When is the best time of year to do this?  I live in Northern Indiana.  Thank you for advising.  C. C., Merrillville, IN; 2/3/03
A:    Pine, spruce and fir trees can be pruned in early spring.

Q:   How much and how often do I need to deep root water my trees and bushes considering the current drought conditions in Colorado.  I am mostly concerned about a 50 ft elm, and 3 twenty foot crabapples, and 2 15 to 20 ft pine trees.  I also have around 10 aspens in the 10 to 20 ft range.  B. W., Aurora, 1/14/03
A:  During the winter months you should water once or twice a month if there has been little or no snow.  Water when the temperature is above freezing and the soil isn't frozen.  Try to water early in the day so the water can soak in or evaporate before nightfall when temperatures drop.  This will prevent water that collected in cracks and crevices of tree trunks from freezing and damaging the trunks.  To determine how much water a tree needs measure the diameter of the tree's trunk in inches.  Apply approximately ten gallons of water per inch in diameter.  Be sure to water the entire root zone area, not just by the trunk.  The root zone extends to a width that is about twice the height of the tree, or more.
  Water established shrubs once or twice a month also, depending on weather conditions.  Small shrubs (3 feet tall or smaller) should get about five gallons of water.  Medium-sized shrubs should receive about ten gallons.  Large shrubs (over six feet tall) should get between 15-20 gallons of water.  As with trees, direct the water throughout the root zone, not just at the trunk.  For additional information, please see

Q: Hi!
  I've got a small Norwegian Pine which seems to have been insufficiently watered. I have given it the water it needs and kept its pot in a window for light.  I noticed small bugs in the soil.  I also know what to do for these. However, the needles on certain parts of the tree have fallen.  Some entire branches have even snapped off. This tree has four trunks, each smaller than the next.  The biggest trunk is the one that's seemed to do the worst.  I am wondering if I can carefully cut this trunk down altogether and whether the remaining three trunks would do well.  I'm also hoping to one day plant this Norwegian Pine outdoors.  Will it do well here in SE Lower Michigan?  Our soil is almost all clay, and the weather is very unpredictable in ALL its seasons. For now, I just want the tree to be healthy.  What should I do NOW??? Thanks.  L. A., Gibraltar, MI; 1/4/03 
A:   You may prune off any areas of your Norwegian Pine that you feel should be removed.  A good guideline when pruning is to remove no more than one third of the plant per year.  Whether the remaining sections of the tree will do well is hard to predict.  If you corrected the watering problem soon enough, can control the bugs in the soil, and can provide a suitable environment, the tree hopefully will survive.  Provide sufficient water, but be careful not to over-water the tree.  Yellowing needles are a sign of too much water.  Be sure the tree gets ample sunlight while in the house.  It will also need a sunny spot when you move it outside.  You live in USDA Hardiness Zone 6, so it should do fine outside.  A potential problem is the clay soil.  Pines require good drainage.  Try to select a site that is high.  If your property is flat, you may want to build up a berm to plant it in.  Amending the soil with compost will also promote drainage.  Good luck.

Q:   Hello, I could use some advice. I just bought 2 acres near Fairplay (same elevation) and want to plant some conifers as a wind break/food source for native animals on it.  They would get the north wind and will be fairly close to a stand of aspens, to their south.  When is the best time to plant these trees also?  Thank you very much.  K. C., Denver, 11/11/02
A:   Due to the high elevation of Fairplay and the surrounding area, probably the best conifer to use as a windbreak is limber pine (Pinus flexilis).  While several other trees would be good windbreaks, they wouldn't survive at such a high elevation (about 9900 ft.).  You might want to plant some shrubs that have berries for wildlife next to the trees as part of the windbreak.  Some shrubs that are hardy to 10,000 feet include Serviceberry (Amelanchier alnifolia), Peking Cotoneaster (Cotoneaster acutifolius), American Elder (Sambucus canadensis), and Canada Buffaloberry (Sheperdia canadensis).  The best time to plant these trees and shrubs is in spring once the ground isn't frozen.  Good luck with gardening at this elevation.  It will be a challenge!

Q:   I have several smaller Blue Spruce trees that have been doing very very well...until now. They each have (had) at least 6 inches of new growth on them, but suddenly they all started to droop from the top down. I have been very careful to keep them watered - at least I thought I had...Of course I'm thinking 'drought', but I'm wondering at what point it's too late to save them...and it the drooped part will come back if I water more...??  Thanks!  C. P., Colorado Springs, 6/28/02
A:   Drooping from the top down and outside in can be a sign of insufficient water.  Be sure to water the entire root zone, not just the area by the trunk. Deep watering rather than frequent shallow watering is preferred. Check the moisture level frequently by digging down with a small hand shovel. Evergreen trees require winter watering.  If the trees didn't receive sufficient water in winter they will appear fine in spring and then die when the weather warms up.

Q:   I just had a young crabapple tree planted a couple days ago.  My landscaper friend and I picked it out at a nursery in Parker.  Its leaves were wilting at the very top on many of the branches and have since died.  The landscaper called it wind burn and also mentioned that the top of the root ball might not have been wrapped as high as it should have been.  I've been told two conflicting things:  1) trim the dead tops off now and 2)leave them alone because it's best to do it in the winter AND because a second growth could still happen this summer.  Advice?  Thanks!  L. S., Denver, 6/13/02
A:   Do not trim the crabapple tree now.  With sufficient water some of the branches may leaf out again.  When in doubt, I always prefer to give a plant a chance to recuperate before chopping off parts that may still be healthy!  More importantly, crabapple trees are very susceptible to a disease called fire blight.  Disease organisms can enter the tree through wounds and cuts.  Warm and/or rainy weather promote the spread of this disease.  Therefore, these trees are pruned in late winter or early spring while they are dormant and the weather is cold.

Q:   Our elms, both Siberian and American, have extensive leaf drop this year.  Leaves all or partially brown out prior to dropping.  When examined on the tree, there is a black, sort of kinky, material inside the leaf.  Looks like an insect of some kind but have not seen larva or eggs.  Believe we had this last year, but much worse now.  Thought it might be Elm Leaf Beetle, but the leaves are not lacy, or chewed through.  T. H., Lakewood/ 6/9/02
A:   Without seeing a sample, it is difficult for me to determine what the problem may be with the elm trees.  Some possibilities include insects -- if the black, kinky material is droppings, sooty mold, or spiny elm caterpillars.  I suggest that you take a sample to your county CSU Cooperative Extension office or to a garden center that has staff who can diagnose exactly what the black material is and then advise you regarding treatment.  Due to the value of established trees in the landscape, I suggest you do this soon.

Q:  Hello, are there any very small trees or shrubs that could survive year round in a container on my  partial-shade, covered patio? And do you have any suggestions for the same type of thing, that could easily be moved indoors for the winter season?  K. S., Greeley, 6/2/02
A:   It is extremely difficult to over-winter trees and shrubs planted in containers here.  The soil and root ball will freeze, preventing the plant from absorbing water.  Our drying winds compound the problem.  The freeze/thaw cycles in spring are also quite damaging.  I encourage you to invest in plants that can be used outdoors while the weather is nice, and then be moved indoors.
  I have a few suggestions regarding moving the plants indoors.  Before bringing the plants inside, hose them off to remove dust and pests.  Remove any dead leaves, flowers or other debris from the top of the soil or on the plant.  Choose a spot in the house that has bright light (a western or southern exposure).  You may want to keep a lamp on in the evening for a few hours to provide additional light for the plants.  Water the plants as needed, being careful not to over-water.
  Some plants to consider include Azalea, Bougainvillea, dwarf citrus trees, Ficus trees, Geraniums, Hibiscus, Hydrangea, as well as many others.  If the plants have been kept indoors at the garden center, you may need to put them outside for only a few hours each day, gradually increasing the time spent outdoors.

Q:   We planted a Linden tree about two months ago.  The leaves just came out 2-3 weeks ago.  The leaves now look "limp" or "wilted."  We checked the soil about 3-4" down and it is damp.  Does it need more/less water or what could cause the wilting?  We received snow & cold weather 4 days ago.  Thank you.  D. K., Castle Rock, 5/27/02
A:   It is very likely that the cold weather was a factor in causing the leaves of the linden tree to wilt.  If the soil is moist, do not apply more water.  Too much water suffocates plants, resulting in wilted leaves and eventually death.

Q:   I live in Midwestern Wisconsin and was wondering what the advantages/disadvantages of planting a Tulip Poplar in my backyard with full sun are.  Any information you could give me would be appreciated.  Thanks.  L. A., Chippewa Falls, Wis.; 5/11/02
A:   I found the following information about the Tulip Poplar tree (Liriodendron tulipifera).  I hope you will find it helpful.
  The Tulip Poplar tree needs moist, rich, well-drained soil.  The pH of the soil should be neutral to slightly acid.  It requires full sun and regular water.  A fast-growing tree, it can reach a height of 60 - 80 feet and a width of 40 feet.  Thus, it is a good shade tree in yards that have sufficient space.  If space is a problem a slower-growing, smaller cultivar such as Columnar 'Arnold' ('Fastigiata') or 'Aureomarginatum' ('Majestic Beauty') might be a better choice.  Found in the eastern U. S., this tree grows well in USDA hardiness zones 5 - 9 (and possibly zone 4).  The tree usually does not bloom until it is several (12 or more) years old.  In addition to the flowers, the tree is liked for its fall color.  The tree may be difficult to get established.  Also, it may be hard to garden under the tree due to its shallow root system.

Q:   We are moving to Ridgway, Co.  I can't find a plant hardiness map that shows Ouray County large enough for me to determine what our hardiness zone is.  What plants would you suggest.  We have a south sloping lot with mostly pinyon pines and a few types, but not ponderosa or Aspens.  When we are living there, we plan to plant some Aspens.  Do you recommend this?  Thanks.  N. B., Davison, MI; 5/3/02
A:   Your hardiness zone appears to be Zone 4 or Zone 5.  Aspen trees are frequently planted in both of these zones, although they are best suited to the mountains.  Given the frequency of drought conditions in Colorado in recent years, I'd encourage you to plant shrubs and perennials that do not require a lot of water.  Limit the amount of lawn because it needs lots of water -- as well as regular applications of fertilizer, mowing, edging, weeding, etc.

Q:    How do I take care of a weeping pussy willow tree in Colorado?  J. O., Littleton, 4/17/02
A:    Weeping Willow trees and Pussy Willow trees and shrubs like lots of water.  They usually can tolerate poorly drained soil.  They are prone to problems with insects such as aphid and scale.  Inspect them frequently for pests and take action promptly if pests are found.  Willows are fast growers, but unfortunately they do not live very long.

Q:    I live in Colorado Springs.  I am removing an old Russian Olive tree from my front yard.  I would like to know what type or types of tree I can plant in its place.  My house faces west and receives quite a bit of sunlight.  The soil is clay.  What would you recommend?  D. V., Colorado Springs, 3/21/02
A:    If you want a shade tree you might consider these:
       White Ash (Fraxinus americana) 'Autumn Purple'
       Green Ash (Fraxinus pennsylvanica) 'Marshall's Seedless' or 'Patmore'
       Littleleaf Linden (Tilia cordata) 'Glenleven' or 'Greenspire'
       Norway Maple (Acer platanoides) 'Deborah' or 'Emerald Queen'
Be sure to consider how high and wide the tree will be at maturity when selecting a tree.  You didn't mention how much space you have for the new tree, but because your house faces west and gets afternoon sun I assumed you would want a shade tree.  Some nice, smaller ornamental trees are available if the yard is small:
       Thinleaf Mountain Alder (Alnus tenuifolia)
       Birch (Betula) -- several types are available
       Hawthorn (Crataegus) -- several types are available, such as Washington (C. phaenopyrum), Cockspur (C. crusgalli) and Russian (C. ambigua).  Most have thorns.

Q:    In Y2000, I purchased 2 Dwarf Alberta Spruce (Picea glauca "Conica") from a local nursery. I planted each tree in a large 1-inch thick foam pot located in a semi-sunny and wind-sheltered location in my fenced patio. Trees were watered regularly when top-soil seemed dry and fertilized 2x yearly with appropriate evergreen fertilizer. In the first year, one tree browned-out and died, first dropping its needles from near the trunk progressing out to the branch tips. This year, the second tree is following the same brown-out pattern. Thinking perhaps there was an unseen pest on the trees, they were sprayed twice yearly with insecticidal soap solution.
   Why am I losing these expensive trees even though they have received constant attention and care?
   As a substitute for dwarf Alberta Spruce, are there any potted specimens of upright juniper or yew which might be acceptable patio applications (8 ft. maximum height)? Thank you.  C. H., Lafayette, 3/3/02

Follow-up question:
   On Mar. 16, you were kind enough to give me some valuable suggestions regarding my project to grow upright junipers in pots. Thank you for your inputs.
   As an alternative to small upright junipers in pots, what do you think about growing the following in pots:
       Emerald Green Arborvitae, Thuja occidentalis "Smaragd'
I would appreciate your thoughts on this species. Thanks. 3/20/02
A:   Growing trees and shrubs in containers is not easy in Colorado.  The biggest challenge is to provide the right amount of water.  If the plant is over-watered it will die, so good drainage is essential.  The pots should have drain holes.  If the pots ever dried out completely, that may have caused the plants to die, even if they showed no symptoms immediately and were later watered well.  A soil moisture meter like the ones used for houseplants would be helpful for determining when to water the containers.  Unfortunately, even when watered properly, evergreen trees and shrubs such as Alberta Spruce tend to dry out in Colorado's excessively dry climate due to loss of moisture through the needles. The root system can't replace the lost moisture fast enough.  In winter it helps to spray evergreen plants with Wilt-pruf to prevent moisture loss.
   Another problem with plants in containers is temperature.  In summer the soil is likely to heat up excessively and in winter it is likely to get too cold.  Because pots often don't provide enough insulation, the plants are at risk.  The larger the pot, the better the chance for survival.  One source I consulted recommended pots with a minimum depth of two feet and a minimum diameter of 24 - 30 inches. 
   Unless you actually see signs that a pest is present, I suggest that you avoid using pesticides -- even milder ones like insecticidal soap.  Some plants are sensitive to pesticides.  Instead, spray the tree with a strong jet of water.
   Plants in containers do require more fertilization than those planted in the ground.  The frequent watering that container plants require leaches, or washes out, the minerals in the soil.  Diluted solutions applied more frequently would reduce the chance for fertilizer burn and keep soil mineral levels more consistent.
   There are a few upright junipers you might consider for your containers:  Chinese Juniper (Juniperus chinensis) 'Blue Point,' Rocky Mountain Juniper (Juniperus scopulorum) 'Medora' and Rocky Mountain Juniper (Juniperus scopulorum) 'Gray Gleam.'  Yews aren't the best choice for containers here.  They tend to be finicky.  I wish you luck.

Response to follow-up question:
   Arborvitae, like yew and Dwarf Alberta Spruce, is a risk.  All require afternoon shade, protection from the wind, and winter protection.  Instead of upright junipers you might like a dwarf pine:
       Scotch Pine (Pinus sylvestris) 'Nana' or 'Fastigiata'
       Tanyosho Pine (Pinus densiflora) 'Umbraculifera'
       Dwarf Mugo Pine (Pinus mugo) -- several cultivars are available
These plants will tolerate sun and heat, and they require less water than arborvitae, yew and Dwarf Alberta Spruce.

Q:    I'm trying to locate information for my sister regarding the care of the Colorado Blue Spruce tree. We live in South Carolina & realize it's probably for another zone. Our mother, however, had planted some and one survived our weather. It is now approx. 10-15 feet tall. Our mother died and my sister (living in the house) wants to be sure it survives.
Any special feedings required, etc.  Thanks for your help.  G. W., Columbia, S. C.;  3/19/02
A:    Some sources indicate that Colorado Blue Spruce will grow satisfactorily in your zone, USDA Hardiness Zone 8.  In Colorado's dry climate gardeners must be sure the trees receive enough water.  I suspect you normally get more rain than we do, so this usually won't be a concern.  However, if you do have hot, dry spells or drought, be sure to water the tree.  Hosing off the tree with a jet of water periodically will help to control pests.  It probably doesn't need any fertilization.  It's too bad we don't know if your mother did anything special to nurture it.  I hope it will continue to thrive for many years to come as a fond remembrance of her.

Q:    Hi, I was just curious as to why there aren't any Yucca Rostratas (yucca trees) in Colorado and especially the Denver area? I have heard that they are pretty cold hardy to zone 4. Do you know of any plans for some to be planted anywhere? Any info. back would be great. Thank you.  L., 1/7/02
A:    Sunset Western Garden Book does not list Yucca rostrata as suitable for Colorado's climate zones.  I do not know of plans for them to be planted anywhere.  There are other types of yuccas that can be grown successfully here: Y. baccata, Y. filamentosa, Y. flaccida, and Y glauca, for example.


   I live outside of Steamboat Springs, and we have many trees on our property (elev. 7200').  I am concerned because many of them seem to be dying.  I have been cutting the dead ones down and using them for firewood, and I notice that they seem to be decayed inside, and some have ants and ant burrows.  I don't know if they are infesting the trees before or after they die.  Is there something I can do to save the healthy ones, or is this simply a natural attrition?  P. P., Steamboat Springs, 1/7/02

A:    I suspect the ants are carpenter ants.  These ants form nests inside rotting wood.  They do not cause the decay.  In order to save the healthy trees you need to find out what is causing the decay.  It could be a disease or a pest.  I suggest that you contact the Colorado State Forest Service.  The number for the Steamboat Springs District is 970-879-0475.  One of their missions is to help with problems such as this.  Also, you can contact your county CSU Cooperative Extension Service for diagnosis of the problem and treatment recommendations.  The number for Routt County is 970-879-0825.  A third option is to contact a certified arborist in your area.  They are listed in the yellow pages of your telephone directory under "tree service."  You are wise to look into the problem now so that preventative action can be taken to save the healthy trees.

Q:    I live in Whitefish, Montana, but I thought I might ask you a question or maybe you could send me to a website that would help me find an answer to my question.  We live in a unique micro-climate near Whitefish.  The temperatures are usually several degrees colder than in town.  Also we get the brunt of the northerly winds.  We have tried several maple trees and they have all died, usually after a late spring frost.  Why?  We also have planted things for fall color and they don't turn the red color that those same plants in other areas do.  What is wrong with our area.  Could soil be a factor?  Please give us some hints on what to try or plants that might work better.  We are tired of losing the trees.  Thanks.  M. P., Whitefish, MT; 10/28/01
A:    I have a few suggestions that hopefully will be helpful:
1. Whitefish, Montana, is in USDA Hardiness Zone 4b.  Because of the northerly winds and colder temperatures where you reside, you probably should select plants that are hardy to Zone 3.  Try to buy plants grown locally or in other northern areas because they will be better acclimated to your area.
2. Avoid planting trees in the fall.  Instead, plant trees in the spring as soon as the soil can be worked.  If you have a short growing season, spread a 4 inch layer of mulch over the root zone of plants in the fall before the ground freezes to extend the root growing season.
3. Wrap the trunks of young trees from the base up with commercial tree wrap in the fall.  This will prevent sunscald damage that can cause trunks to split and become disease-prone.  Remove the tree wrap in spring.
4. Get a soil test to determine any problems with the soil.  You may need to add amendments to improve the tilth and drainage.  You may also need to correct nutritional deficiencies.  Local garden centers or the Montana State University Extension Service in Bozeman may offer soil tests.
5. Water trees and shrubs in the winter when the soil is not frozen and air temperatures are above freezing if there has been no rain or snow cover for four to six weeks.
6. Avoid planting rapid growing, lush trees with borderline hardiness, such as Silver Maples.  This type of tree is more likely to be severely damaged by a late frost.  Instead, select medium or slow growing trees such as Norway Maple or Green Ash.  (Deciduous trees are more tolerant of cold temperatures when they are dormant during winter.  New growth in the spring is tender, making plants highly susceptible to damage by a late freeze.)
7. Many plants that are popular for their fall color need to be planted in an area that gets full sun in order to produce a colorful fall display.  Cool temperatures, moisture and shorter days (less daylight) are key factors for fall color.
8. I suggest that you contact the Montana State University Extension Service in Bozeman for additional information.  They have a website that I think you'll find helpful:

Q:    I have a question regarding some maple trees which I have in pots, each about 6 inches tall. I'm wondering what I should do with them over the winter: a) plant them outside now b) keep them in their pots and bury the pots in the ground c) keep them in their pots and bring them inside d) keep them in their pots and keep them in the garage where there is some sunlight but it gets cold in winter e) other. I live in Rhode Island by the way. Let me know what you think. Thanks.  B. B., Portsmouth, RI; 10/7/01
A:    I suggest that you keep the maples in their pots and put them in the garage.  Many maples are hardy so the coldness shouldn't be a problem.  It is too late to plant them and the inside of the house would be too bright and too warm.

Q:    We just bought our first house in a covenant controlled community and want to plant some trees.  We are limited on space and would like to keep the trees in a container instead of planting in the ground.  We do not have to get covenant approval on any plants if they are potted but do if they are in the ground.  If you could give us some good ideas as to what trees would do good here in pots as well as how to keep them growing and what type of pot to use that would be great!  B. A., Englewood, 8/30/01
A:   I would like to discourage you from planting trees in pots rather than in the ground.  It is very difficult to keep potted trees healthy.  The amount of space for roots in a pot often is too limited for good root development.  Our freeze/thaw cycles in winter are hard on the trees as well as the containers, which will tend to crack.  Watering the trees is also a year-round challenge.    Some small trees to consider for limited spaces include the following:
Gambel oak (Quercus gambelii)
Callery pear (Pyrus calleryana) 'Redspire', 'Bradford', or 'Aristocrat'
Newport Plum (Prunus cerasifera 'Newport')
Crabapple (Malus) 'Royalty', 'Snowdrift' and several other cultivars.  Be sure to select  trees that are resistant to fireblight.
Thornless Cockspur Hawthorn (Crataegus crus-galli inermis) Several other hawthorns are beautiful, small trees but have major thorns.
Amur Maple (Acer ginnala)

Q:   Is it okay to plant new trees this time of year (July 27)?  K. R., Colorado Springs, 7/27/01
A:   While spring is the best time of year to plant new trees, they may also be planted in summer and fall.  However, you should avoid planting evergreen trees in the fall because their root system isn't able to provide sufficient moisture during our winter weather.  Deciduous trees tend to fare better.

Q:    I have a blue spruce that has been in two years.  The new growth is turning brown and curling.  The existing branch (needles) discolor to a purple hue.  Any ideas as to what this could be?  Any remedies?  A. H., Golden, 5/29/01
A:    Your description sounds a lot like frost damage:  downward curling tips that turn reddish or brown.  Prune off the damaged tips, give the tree a good drink of water, and keep your fingers crossed!  If the tree doesn't perk up soon, take a sample to the  Jefferson County CSU Cooperative Extension office in Golden.  They have an excellent diagnostic clinic.

Q:    With the freeze/snowfall we had last week, many of my trees and shrubs have dead leaves.  My locust tree had just leafed out and all its leaves are brown.  Many of my rose and lilac bushes have either brown or wilted leaves.  Should I prune back where leaves are crispy?  What are the chances the shrubs will recover? C. G., Littleton, 5/23/01
A:    Established hardy trees and shrubs often recover from a late spring frost. Wait to see if damaged branches leaf out again rather than pruning them off immediately.  If after a couple of weeks the damaged branches show no sign of re-leafing, prune them off.

Q:    What are the advantages/disadvantages of planting an Austrian pine versus a Ponderosa pine?  Why would you plant one or the other?  J. E. 5/1/01
A:    The choice of an Austrian Pine vs. a Ponderosa Pine is mainly a matter of personal preference.  The Austrian Pine is a bit shorter and wider and has dark green needles year round, while the needles on the Ponderosa Pine turn yellow-green in fall and winter.  The Austrian Pine tends to be more dense. The Ponderosa Pine is a native and requires less moisture.

Q:    I have a large crab apple tree in my backyard.  Last season it produced an overly abundant amount of apples.  We were hoping to trim the tree to limit the apple production, but the tree company said it was too late in the season to trim and could cause "fireblight".  I am wondering what that is, and if you thought it might be ok for us to do some of the trimming ourselves without hurting the tree?  S. F., Boulder, 3/28/01   
A:    Fireblight is a bacterial disease that is very destructive to crabapple trees.  Infected twigs, leaves and fruit will look wilted, turn black as if scorched and exude a bacterial ooze that will attract aphids, ants and other pests.  The bacteria become active when the weather is warm (60's) and wet.  Insects and even rain splash will spread the disease.  Bacteria often enter trees through wounds, including pruning cuts.  Therefore, crabapple trees should be pruned in winter when the weather is cold and the bacteria are less active.  Also, winter pruning provides time for wounds to begin to callous before the height of bacterial activity.  While there is no cure for this disease, there are sprays that can be used a preventative treatment when necessary.
   Since an abundance of fruit, not the size of the tree, is the real problem, I suggest that you spray the tree with a product that will limit or eliminate the production of fruit.  One such product is Florel.  The tree should be sprayed when it is in mid or full bloom, before fruit set.  To find out more about this product look at the manufacturer's website: Next winter you can prune the tree if you don't want to use a spray to limit fruit.

Q:    We live in an area where our soil is like clay.  We have planted Blue Spruce and Norwegian pines that are about 3 feet tall.  We have watered, fertilized, and protected them from the wind in the winter, but cannot get them to survive.  If you have any suggestions or any other type of trees we should plant please let me know.  We would also like to know when is the best time to fertilize in the spring?  What fertilizer do you recommend to use?  G. R., Fort Lupton, 4/1/01
A:    I have a few suggestions concerning the planting and care of evergreen trees that hopefully will be helpful.

1) In Colorado, be sure to plant evergreens such as spruce and pine in the spring, not the fall.  Our winter weather dries out newly planted evergreen trees that haven't had time to establish a root system strong enough to supply sufficient water for the tree.
2) In the fall spray young trees with "Wilt-pruf" to limit evaporation. Also, place a mulch over the soil to retain moisture.
3)Fertilizers encourage new growth.  Because new growth is more susceptible to winter damage, do not fertilize evergreens in the fall.  Also, wait until a newly planted tree's roots are established and capable of sustaining current growth before encouraging the plant to put on new growth it isn't ready to handle.
4) Drainage is poor in clay soils, causing plants to suffocate and die because water fills up the air pockets.  To improve drainage, amend the soil with compost.  Avoid over-watering.  Also, you may want to consider planting trees on mounds that allow water to drain away from the roots.
5) Hopefully, you will have success with natives such as Blue Spruce, Pinyon Pine, Southwestern White Pine or Limber Pine.

   The time to fertilize varies from plant to plant, but generally is done as plants come out of winter dormancy and the danger of a killing frost which could damage new growth is past.  Avoid using fertilizers high in nitrogen on flowering shrubs, perennials and annuals.  You will get lots of leaves and few flowers.  Water soluble fertilizers (e.g., Miracle-Gro) are popular.

Q:    I have these trees in my backyard.  I think they are a variety of cottonwood.  The problem is they are sending shoots up everywhere: in my yard, in my grass, in my neighbor's yard.  Some are as far away from the tree as 30 feet.  It's like it's some kind of alien taking over.  I'm scared to put anything on them to kill them because I don't want to kill the tree.  Any suggestions?  L. P., Littleton, 4/24/01  
A:    Members of the poplar family, which includes cottonwoods and aspen, are known for their habit of producing shoots, or suckers.  Also, many of these trees produce seeds which sprout up all over.  About all you can do is snap off or cut off the suckers and pull up new sprouts before they get too big.  Many gardeners avoid planting these trees because the suckers are such a nuisance. Good luck!

Q:    My wife and I are soon to become first time homeowners.  As an avid appreciator of trees, and someone who comes from the species/genus rich east coast, I am interested in planting some trees in our new yard that are unique to this area.  I have highlighted a few types, but can't seem to find out if they will survive in the Colorado climate.  Moisture seems to be the biggest concern, followed by oxygen quantity.  Can you please advise if any of the below trees would be hearty enough to not only survive but flourish in the Denver area:  American Beech, American Chestnut, Chestnut Oak, Yellow Poplar, Sweetgum, Sassafras, Kanzan Cherry, Yellow Buckeye, Silver Linden, White Ash, Ginkgo and Eastern Hemlock.  S. B., Louisville, 3/8/01
A:   The following trees can perform well here if given the right growing environment --sunlight, water, soil, etc.  If you choose to plant any of them, be sure to check out any specific needs the tree may have.

Quercus -- I did not find Quercus prinus.  However, there are many types of oak that do well here:  Bur Oak (Q. macrocarpa), English Oak (Q. robur), Northern Red Oak (Q. rubra) and Swamp White Oak (Q. bicolor).

Yellow Poplar (Liriodendron tulipifera) -- It is known here as Tulip Poplar.  It does well but may be difficult to find.

Yellow Buckeye (Aesculus octandra) -- I found Aesculus flava referred to as Yellow Buckeye and it is listed as suited to this area.  Ohio Buckeye is more commonly used.  A word of caution: the buckeye, or seed, is poisonous.

Silver Linden (Tilia tomentosa) -- Linden trees are a good choice for this area.  They can tolerate our alkaline soil.  They should be protected from sunscald and require additional water in dry weather.  Look for new cultivars that are resistant to aphid and scale, such as 'Green Mountain.'

White Ash (Fraxinus americana) -- Ash trees can have problems with ash/lilac borer and ash sawfly, but are worth the effort.  They benefit from improved soil.  Good cultivars include 'Autumn Purple,' 'Elk Grove' and 'Empire.'

   Several of the trees mentioned above grow to be quite large, so be careful to check out the planting site to see if it can accommodate the mature size of the tree.  Good luck with your new home.

Q:    I am planning my landscaping for my front and back yards.  I have limited space and budget.  I want to choose three trees, all small, and some small to mid size bushes.  Do you have any recommendations of things that will give great spring and fall color?  Fall color is especially important to me.  My front yard is a slope, any suggestions?  A. L. , Denver, 10/23/00 
A:    Below are some suggestions of trees, shrubs and groundcovers that will provide color in spring and/or fall. I included groundcovers since you mentioned that your front yard is a slope.

Washington Hawthorn (Crataegus phaenopyrum): white flowers in spring, red berries, fall color
Thornless Cockspur Hawthorn (Crataegus crusgalli inermis): same traits as above but without the thorns
Flowering Crabapple (Malus): Be sure to get a variety resistant to fire blight, for example
'Radiant' -- deep pink blossoms, bright red fruit
'Coralburst' -- double rose pink blossoms, reddish orange fruit
'Profusion' -- purplish pink blossoms, red fruit
Tatarian Maple (Acer tataricum): fall color
Flame Amur Maple (Acer ginnala 'Flame'): fall color

Spring color:
Spirea -- many varieties such as Spirea x vanhouttei 'Snowwhite' or Spirea x bumalda 'Froebelii'.
Small-growing rosebushes such as 'Bonica', 'The Fairy'
Fall color:
Compact American Cranberry (Viburnum trilobum 'Compactum') -- 4-6' tall, white flowers in spring, red fruit, orange-red leaves in fall
Dwarf Burning Bush (Euonymus alata 'Compactus') -- 4-6' tall, scarlet red leaves in fall if grown in a sunny spot

Periwinkle (Vinca minor) -- blue flowers in spring, retains leaves in winter
Kinnikinick -- flowers, small red fruit, leaves turn reddish in winter

Creeping phlox (Phlox subulata) -- flowers in early spring
Creeping Potentilla (Potentilla neumanniana) -- yellow flowers in summer, red fall color
Stonecrop (Sedum) -- flowers, succulent-type leaves, seed heads in winter

Q:    I have 16' between my house and my fence.  I want to plant some columnar trees.  I live in Highlands Ranch.  I was thinking of either columnar English oak or columnar hornbeam.  Are these good choices?  K. E., Highlands Ranch, 8/16/00 
A:    Columnar trees should work well in the 16' space between the house and fence so long as they won't eventually grow too large.  My information indicates that columnar English oak (Quercus robur 'Fastigiata') may become 15 to 20 feet wide.  It tends to become chlorotic (the leaves turn a sickly-looking yellow) due to our highly alkaline clay soil.  Columnar European Hornbeam (Carpinus betulus 'Fastigiata') grows slowly to a width of 15 to 20 feet and would appear to be a better choice because it can be clipped.  You might also want to consider the Hawthorn (Crataegus).  There are several attractive varieties that work well in small spaces.  Rocky Mountain Birch (Betula occidentalis) and Rocky Mountain Maple (Acer glabrum) are other possibilities to consider.