When one hears the word "bulbs" images of spring-blooming tulips and daffodils usually pop to mind.  We tend to forget that some of summer's most stunning flowers come from summer-blooming bulbs.

          Blooming between June and September, begonias, callas, cannas, dahlias, caladiums and gladiolus are just some of the many beauties that grow from bulbs.  (The term “bulb,” as commonly used, refers to corms, tubers, tuberous roots, rhizomes and true bulbs.)  For the best selection, you should purchase bulbs at garden centers early in spring or order them through garden catalogs or websites.  Because summer-flowering bulbs aren’t cold hardy like their spring-flowering cousins, they must be planted after the danger of frost is past—about the middle of May along Colorado’s Front Range.  Select planting sites in your garden that meet the varying sunlight needs of these plants.  Cannas, dahlias and gladiolus like sun, callas and begonias prefer partial shade, and caladiums need shady sites.

         Most bulbs require a rich soil with good drainage or they will rot. Therefore, you should prepare the soil by adding a one-inch layer of organic matter such as peat moss or compost.  

You should also add a fertilizer for bulbs. Superphosphate or 5-10-5 complete fertilizers are recommended.  Avoid high nitrogen fertilizers that stimulate leaf growth rather than flower production.  Mix these amendments thoroughly into the soil before planting the bulbs.  As a general rule of thumb, bulbs are planted at a depth that is 2½ to 3 times the diameter of the bulb.  Once the plants begin to bloom, cut off faded flowers to prevent seed formation and to encourage continued bloom.

         Because these plants are not cold hardy, in the fall when the plants’ leaves turn yellow, you should dig up the bulbs and prepare them for storage.  Use a spading fork to loosen the soil and lift the bulbs out of the ground.  Gently clean the bulbs off.  Store gladiolus in a single layer in a ventilated tray.  Caladiums can be stored in dry peat moss or vermiculite.  Store tuberous begonias and callas in sawdust.  Cannas and dahlias can be stored in perlite, vermiculite, sawdust or peat moss.  Keep the bulbs in a cool, dry place such as a basement, shed, or garage where the bulbs won't freeze.  When the month of May arrives next year, inspect the bulbs and discard any that are diseased or have rotted.  Plant the healthy bulbs for another colorful summer garden.