Iowans are currently enjoying the beauty of tulips, daffodils, and other spring-flowering bulbs. Proper care of these plants through the remainder of spring and early summer helps to insure repeat performances in succeeding years.
Remove the flower heads on tulips and daffodils as soon as the flower heads fade. This prevents the plants from expending large amounts of energy in fruit (pod) development. The weakened bulbs need the food manufactured by the plant foliage.
After blooming, two to three pounds of a 5-10-5 or similar analysis fertilizer may be applied to 100 square feet of bed area. To prevent burning of the foliage, wash off any fertilizer which remains on the leaves. Control weeds which compete with the plants for water and nutrients. Often hand weeding is most practical.
The foliage of spring-flowering bulbs should not be removed until it has turned yellow and begun to die back. The length of time it takes the foliage to die back depends on bulb type, weather, and cultural practices. Most tulips and daffodils don't die back until late June or early July. Premature removal of plant foliage reduces plant vigor and bulb size, resulting in fewer flowers next spring. After the foliage has yellowed, it can be safely cut off at ground level and discarded.
If spring-flowering bulbs need to be moved, carefully dig up the bulbs when the foliage has died back. The bulbs can be separated and replanted immediately. If the bulbs can't be planted until fall, allow them to dry for 2 to 3 weeks then store the bulbs in a cool, dry place. Periodically inspect the bulbs during the summer and discard any which show signs of decay.
This article originally appeared in the April 14, 1995 issue, p. 43.