Adding bulbs to a garden is rewarding for several reasons. They extend the season of bloom since some bulbs flower early and others bloom in the fall. And, they're relatively easy to care for once planted. Bulbs are quite undemanding under most circumstances.
The most important fertilizing for bulbs is when they're first planted. Add organic matter into the soil along with a high phosphorous fertilizer dug in at root depth. One-half pound of super phosphate per 100 square feet is adequate.
As bulbs finish flowering, let the foliage mature fully. Remove only the faded flowers and top inch of the flower stem. The remaining foliage and stems will manufacture food for the bulb as they mature or "ripen." When you can easily pull the yellowed leaves and stems from the ground, the process is complete.
A light application of a balanced fertilizer may be given to the plants following bloom. It's best not to apply high-nitrogen fertilizers. Those fertilizers encourage lush foliage at the expense of flowers. Remember that phosphorous and potassium aren't effective if they're applied to the soil surface. They need to be carefully cultivated into the soil below the surface.
If flowering declines, check your cultural conditions. Bulbs grow best in sunny areas, but sunny sites can become shaded with the growth of trees as gardens mature.
Bulbs also should be watered throughout the year in periods of drought.
For more information, see the following Colorado State Extension fact sheet(s).
- Vegetable garden: Soil Management and Fertilization
- Choosing a Soil Amendment
- Spring-Planted Bulbs, Corms and Roots
Updated Friday, April 19, 2013