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When it comes to bulbs we don’t always meet with consistent success. And, before you blame the chipmunks, the girl who mows the grass or the bulb company for their lack-luster performance, consider some of the other factors that influence how well flowering bulbs flower. Sunlight; crowded bulbs; pre-mature removal of foliage the previous season; or a winter rest period that wasn’t cold enough or long enough may play a role in poor performance. The life cycle of a bulb is different than other herbaceous perennials and there are a couple of things we need to understand about them before we start looking for blame.
By definition, a bulb is considered “a plant that spends part of its annual cycle underground as an enlarged storage organ.” This actually says much about what it needs in terms of a life cycle that consists of storing nutrients, resting, chilling and expending energy in the form of blooms.
Bulbs need a climate that suits each species’ needs. Bulbs will do well if they are grown in a similar climate to where the species originated and adapted. The timing and amount of rainfall, and temperatures have more to do with success and failure than many of us realize. For example, many tulip species shrink in size each consecutive year because we do not have a long enough season for them to rest and chill during the winter. This chilling period is necessary to set off a bio-chemical response in the bulb that triggers blooming. For many tulips, especially hybrids, the chilling period needs to last at least 16-20 weeks and the ground temperature should be below 45 degrees.
Other bulbs may rot in the ground during their dormant months in summer or in winter because rainfall is heavier than in their native environment; or it is induced out of the ground by untimely rains or temperate weather only to be hit by a heavy frost that it cannot withstand.
Premature cutting of bulb foliage can lead to disappointing results, too. The foliage of a bulb is how it stores up the necessary nutrients through the process of photosynthesis. If you cut the foliage back too early (or braid, fold or bunch the leaves) the bulb will have little to offer the next year. You must leave the unsightly foliage for at least six weeks (or until it dies back naturally by early July).
None of this is to say that we should give up on bulbs, to the contrary. There are many bulbs to choose from that are suitable to our climate just understand how the timing of weather patterns effects the performance of the bulb and select appropriate varieties for our climate. For example, tulipa tarda is a species tulip that performs well here, however the hybrid ‘Angelique’, nearly a 6-inch bloom in the first year, showed only a couple blooms this spring that barely managed a 3-inch diameter.
If you order bulbs from a catalogue check with companies about the size of their bulbs, if they are offering hundreds of bulbs for a cheap price don’t be surprised when you receive small bulbs too young to do anything until they have stored more energy. Reputable catalogue companies will send large, firm bulbs that are ready to bloom the following season. If you buy bulbs locally select them the same way you would onions at the grocery store. Since bulbs plump up as they store more food always choose bulbs that are firm and large, relative to the species’ size. Avoid soft, withered bulbs and check for mold or rot.
Once soil temperatures dip below about 60 degrees you can start planting bulbs. At this point the bulbs can put out some roots and establish themselves before their winter chilling and rest period. The general rule of thumb when planting any bulb is rich, well-drained soil. The planting depth can be determined by measuring the diameter of the bulb and multiplying by three; so a bulb with a 2-inch diameter should be planted six inches deep.