Fertilize your spring flowering bulbs with a slower-releasing granular of one to two pounds of 10-10-10 per 100 square feet when shoots first appear in spring and ideally four to six weeks before bloom. Adding fertilizer in spring produces healthy and robust foliage which consequently allows bulb's to increase stored carbohydrates that will produce a larger bloom the next year. Work in granular fertilizer shallowly around the bulbs. Repeat this application in the early fall when newly growing roots start spreading.
If fertilizer treatments are made after flowering, a quick release of liquid fertilizers should be used to supply nutrients before foliage dies and bulb goes dormant. Compost can be incorporated in the fall, as it releases nutrients gradually in the soil so an additional spring application would not be needed.
Remove flower heads once it has finished blooming to ensure greater energy is returned to the bulb rather than making seeds.
Allow leaves to die back naturally. Leaves will yellow and may become unsightly to some gardeners but is important in the process of making next year's flowers. Never pull but cut back foliage. This may not be necessary for small bulb foliage like grape hyacinths that fade, but bulbs like tulip and daffodil should be allowed to remain in the garden until early July. The longer it lasts, the better the bulbs will grow the following year.
If digging up bulbs by accident or moving bulbs after leaves turn yellow, carefully lift the bulbs, shake off any loose soil and roots, discard small bulbs and store the remainder in a cool, dry, shady, well-ventilated room until fall planting time.
If spring bulbs did not show up here may be some probable reasons:
- If no leaves appeared this spring then it could have been the mischievous squirrels or the bulbs may have rotted from excessively wet soils. Dig the area to determine the problem. If wet, gardeners may need to add compost or move bulbs.
- Bulbs were not big enough when planted.
- Bulbs are planted in an area that is too shaded. Most bulbs need at least 6 to 8 hours of sun while the leaves are photosynthesizing.
- Bulbs may be short-lived. The tulip after flowering disintegrates, producing daughter bulbs, and if planted too shallowly or overcrowded may not flower and may produce leaves only.
- The bulbs were planted too shallowly. When replanting bulbs, make sure to plant at the proper spacing and depth. Larger bulbs such as tulips and daffodils should be spaced 6 to 8 inches apart and 6 to 8 inches deep. Smaller bulbs such as grape hyacinth and crocus should be planted 3 to 4 inches apart and 3 to 4 inches deep.
Kelly Allsup is the University of Illinois Extension horticulture educator in Livingston, McLean and Woodford countie