Bulbs to most gardeners includes any underground fleshy structure which when planted in the correct zone, produces a perennial plant. To botanists, this includes—true bulbs, corms, tubers, tuberous roots and rhizomes. All of these except tuberous roots are modified stems, not roots. They all store energy for the growth and survival of the plant.
Bulbs are generally classified and planted based on their time of blooming. Spring and early summer bloomers (January to May) are usually planted in the fall. These include tulips, daffodils, hyacinth, crocus and other less popular ones. These bulbs require a “chilling period” of various times, depending on the plant, in order to flourish and bloom.
The summer and fall bloomers (June through September) are usually planted in the spring. These bulbs come in two general varieties, cold hardy and tender. The tender ones, such as caladium, tuberous begonia, dahlia and gladiolas will either need to be planted as annuals or dug in fall and stored. In our area cannas and elephant ears are hardy if mulched, further north they need to be dug in fall.
When buying bulbs, do it as early in the season as possible. Remember, with bulbs bigger is better. Larger bulbs have more stored energy and will generally produce better blossoms and foliage.
Planting Bulbs: Most bulbs need full sun or part shade. Spring bloomers do well under deciduous trees, in that they will be going into dormancy by the time trees fully leaf out. Temperatures are important, some tender bulbs such as caladium should only be planted after the soil and air has warmed to over 70 degrees.
All bulbs need well drained soil. They are subject to rots if not. They benefit from the addition of organic material worked into the soil. Working in a balanced slow-released fertilizer is helpful. It is not necessary to fertilize bulbs such as tulips and caladium which are usually grown in our area as annuals.
Often confusion arises about which end of the bulb is up. If you can’t figure it out, plant it sideways. Even if upside down, it may take longer to emerge, but the bulb can figure it out. There several rules of thumb about how deep to plant bulbs, one is that it should be planted 3-4 times the width of the bulb. After planting water in well and apply a layer of mulch which will help conserve water and moderate temperatures.
Maintenance: In the spring remove the spent flowers to allow more energy to be sent to the bulb, rather than forming seeds. Also it is important to not remove the leaves until they turn brown. While green, they are restoring energy into the bulb for next year.
Most perennial bulb plants will form new bulbs and eventually need to be thinned. This is a great way to produce new plants and share with other gardeners.
Fertilizer may be applied to spring flowering bulbs in fall and again in early spring. These plants, such as daffodils, go into dormancy after blooming; applying fertilizer at this time is wasted. Summer and fall blooming bulbs can be fertilized in spring and maybe once more in summer. All of the fertilizer choices are best based on a soil test.