Tulipa: Failure to Grow

Problem
Tulip bulbs do not produce any growth in the spring.

Analysis
Improper cultural techniques, diseases, animal pests, and natural decline can all contribute to lack of growth in tulips.

1. Lack of cooling: Tulip bulbs require a period of cooling to develop properly. They need to spend at least 6 weeks below 50°F in order to perform ideally. If newly purchased bulbs are not precooled, or soil temperatures remain at 55°F or above during the winter, root formation, flower emergence, and the production of new daughter bulbs for future flowering will be inhibited.

2. Foliage removed too soon: After a tulip flowers, the remaining foliage continues to use the sun's rays to manufacture food for the developing new bulbs and next year's flowers. If the foliage is removed before it has a chance to turn yellow naturally, the new bulbs will either be very small or will not form at all.

3. Lack of fertilization: After the first year, tulips will not continue to perform well when planted in infertile soil. They form only weak, small bulbs and flowers. After several years, they will stop producing growth.

4. Root rot: Infected tulip bulbs planted in heavy, poorly drained soil frequently decay.

5. Rodents: Mice, pocket gophers, and other rodents may feed on tulip bulbs. Dig in the area where the bulbs were planted and check for underground tunnels and half-eaten bulbs, both of which indicate rodent damage.

Solution
The numbered solutions below correspond to the numbers in the analysis.

1. In warm-winter areas (zones 9 and 10; see Plant Climate Zone Map for zone map), refrigerate newly purchased bulbs for 6 weeks. For details, see Tulipa.

2. Allow foliage to turn yellow before removing it.

3. Fertilize emerging tulips in the spring with a balanced fertilizer and once a month after the plants have flowered until the foliage dies back.

4. Before planting, discard discolored, spongy, or moldy bulbs. Plant in well-drained soil. For information on improving soil drainage, see Soil Types, Soil Structure, and Groundwater.

5. The most effective method of protecting tulips is to plant them in baskets made of ¼-inch wire mesh. Traps or baits may also be used.