After Bloom Care of Spring Bulbs

There is a time of year they produce and store food reserves that will determine whether or not they flower again next season. Proper care during the after-bloom period is very important. Never cut off foliage while it is still green and actively growing. Healthy, vigorous leaves are necessary for ample food production and proper development of the bulbs.

Removal of these leaves too early stops growth of the bulbs and may keep them from flowering next season. The foliage should be allowed to remain until it naturally begins to yellow and die. At that time it may be removed without any harm. During the bloom time or immediately after bloom is complete, bulbs may be fertilized lightly with a fertilizer fairly high in phosphorous and low in nitrogen. Avoid high nitrogen fertilizers, as too much nitrogen seems to make bulbs more subject to injury or root rots.

A fertilizer such as a 5-10-10 might be used lightly on the surface. Bonemeal is also often applied to bulbs since it is a high phosphorous material. Be sure to keep fertilizer off the leaves and not too close to the base of the plants. Do not use manure among bulbs unless it is very well aged. Flower stems should be promptly removed after bloom is completed. This is done to prevent seed formation which can take stored food away from the bulbs and reduce flowering for the next season.

Bulbs should not be moved during or immediately after flowering. If bulbs must be moved, they should be lifted carefully with a mass of soil still around their roots and carefully planted in another location where they can continue to develop. Digging some of the more vigorous bulbs such as daffodils too early may not mean that they will die, but may weaken them, causing them to fail to bloom during the next one or two seasons.

One of the most important cultural requirements of flowering bulbs is excellent drainage. If some bulbs seem to yellow and die off more quickly than others of the same type, drainage may be suspected. As soon as these have died back, it may be wise to dig them, separate them, and select a new location for them. After the foliage of spring bulbs has matured, yellowed and died off, it should be pulled off and discarded. Although leaf diseases are not a major problem, dead leaves can help to perpetuate any problems that might be present.

After the bulbs have lost their foliage and gone dormant until the fall, they may either be lifted and stored, or allowed to remain in place. Some types, such as daffodils and crocus, are best left in place unless large clumps need dividing. Others, such as tulips, do not endure hot soil temperatures well, and may be dug and stored in a cool, dry location for replainting in fall. When bulbs are left in place and overplanted with annual flowers, avoid excess watering and heavy fertilization of the annuals which might be damaging to the bulbs.

http://urbanext.illinois.edu/bulbs/planting.html