This week's post is the third and final on the topic of spring bulb planting. If you have not read the previous two on soil preperation and planting you may want to check them out before reading this post.
Problems: Bulbs generally get few problems. If bulbs are not growing, but rotting, the soil may be too wet. If rodents or mammals (deer, chipmunks, skunks) are a problem, it may be necessary to cover the beds with fine mesh wire to prevent them from digging out the bulbs. A whole bed of bulbs may be dug out, and lined with poultry wire or similar, to prevent digging. A small handful of sharp, finely crushed shells or rocks (available at complete garden supply stores) can be placed in holes, around the bulb, at the time it is planted to discourage digging. Daffodils are quite resistant to digging and eating.
If daffodils disappear in future years, or look “grassy” with few or no blooms, you may have the narcissus bulb fly. This fly, resembling a bumblebee that hovers and moves faster, lays eggs at the base of bulb leaves in early summer. The larvae tunnel into and eat the bulb, making it rot. Windy sites, planting bulbs among other perennials or lawns to confuse these flies, and destroying affected bulbs, all help prevent spread of this problem
During extended wet weather in the spring, the fungus "Botrytis" (tulip fire) may cause leaf tips of tulips to decay. Cut off and burn all decayed leaf tips as soon as you notice them. Infected buds and foliage showing grayish tan spots should also be eliminated. Removing infected foliage is the most important way to control this disease, although certain fungicides can also be used to help control it.
Spring care: Certain practices in the spring after bloom will affect the growth and development of bulbs for the next few years. Remove any seed pods. (When they are left on, new bulbs of tulips and daffodils are much smaller than when the pods are removed.) Removing the leaves has just the opposite effect, however. After bloom, leaves are needed to produce the food that will go into making the bulb and bloom for the following year. A handful of fertilizer sprinkled around the bulbs after the bloom or watered on will help this process. Let the leaves remain on the spring-flowering bulbs until they show signs of ripening and turning yellow. In the north, this time is usually mid-June for tulips and mid-July for daffodils. Other types of bulbs vary greatly in the date at which they are mature. This ripening process may be hastened by folding over the leaves and putting rubber bands around them.
Clumps of hardy bulbs may only need digging and dividing if they have few or no flowers, or smaller flowers, possibly after 3 years. Allow bulbs to mature as long as possible before digging and dividing. Digging too soon after bloom will keep the bulbs from flowering the following year, although they will flower in the second year. Very small bulbs, especially bulblets separated form large bulbs, may not flower simply because they need a few years to mature. On the other hand, don't wait until the foliage disappears or you won't be able to find the bulbs!
When the foliage turns yellow (usually late June to mid-July), lift the bulbs carefully, free them from soil, remove the tops, pull them apart, and replant immediately. If not replanted at once, they may be washed, spread in an airy and shady place to dry, and then stored in shallow boxes in a cool, dry, airy place until planting time the following fall.
Article Content courtesy Dr. Leonard P. Perry, Department of Plant and Soil Science, University of Vermont Extension