Flower bulbs are a forgiving bunch. They can be buried upside down, stomped on or ignored, yet most will bloom for several seasons.
There are the occasional no-shows, of course — those that fail to flower and deliver the first burst of colour in early spring. Here's why some bulbs fall short, and what you can do about it:
- Bad bulbs: Even proven flower bulbs can go bad. "Give them the squeeze test," said Brent Roozen, spokesman for Washington Bulb Co., the continent's largest tulip grower, in Mount Vernon, Wash. "If there are brown or black spots on them or they're soft to the touch, don't use them."
- Poor timing. Spring-blooming bulbs need time to go dormant if they're to bloom. Planting dates vary with the climate but often extend into the winter. Just get them into the ground early enough so they can develop roots.
- Expired shelf life. "You can't carry them over (from season to season). The bulbs will dry," Roozen said. "When customers ask me about the best time for planting, I always tell them 'today'."
- Crowding. "Bulbs will grow, even if you don't give them enough shoulder room," Roozen said. "But in a few years, the flowers and the blooms will progressively get smaller."
- Predation: "Tulips are the 'chocolate cake and ice cream' of the bulb world if there are voles or deer in the area," said Becky Heath, co-owner of Brent and Becky's Bulbs at Gloucester, Va. "We spray our tulips with a nasty smelling substance to mask their sweet smell, and it really helps, but sometimes for only one year." Daffodils, leucojum, galanthus and colchiums are the bulbs to choose if you want something that no animal eats, she said.
- Environment. "If bulbs are a failure because they fail to bloom year after year, it's probably because the gardener is in 'shade denial'," Heath said. "There can be a lot of sun when the bulbs are in bloom, so that seems like enough sunlight. However, when photosynthesis happens after flowering time, which is crucial for the bulb to generate enough nutrients for the next seasons, the leaves are on the trees and there often isn't enough sunlight. Then the bulbs dwindle."
- Planting depth. "Bulbs planted at too shallow a depth are vulnerable to frost heaves that can expose them to drying winter winds and cold," said Hans Langeveld, vice-president and owner of Longfield Gardens LLC, a source of bulbs and perennials in Lakewood, N.J. Plant tulips and daffodils 15 centimetres deep where winters are the coldest, he said. Plant smaller bulbs like crocus and muscari 10 to 12 centimetres deep.
- Over-watering in summer. Most bulbs come from arid climates and thrive where summers are dry, Langeveld said.
Plan to start a new batch next fall unless bulbs are labelled "Good for Naturalizing," he said. "Most tulips are annuals for American gardeners, but some are famous for coming back, including the Darwin hybrids. Other naturalizers include daffodils and other narcissi, muscari, alliums and crocuses.'Suggest a correction