Regional Gardening Reports :: National Gardening Association

In the Garden:
New England
May, 2011
Regional Report

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These tulips in my back garden are just coming into bloom.

Why Bulbs Fail to Bloom

I was out of town last week. It has been a cold spring here in Vermont, and when I left, the early daffodils and some of the small bulbs like crocus, Siberian squills, and chionodoxa were blooming in my garden. When I arrived back, many of my daffodils (including my favorite 'Ice Follies', which I plant by the dozens), were in glorious bloom, as well as species tulips, hyacinths, and grape hyacinths, with more tulips ready to burst into flower. It is a beautiful show.

Hardy spring-flowering bulbs are usually among the most reliable of garden performers because their flower buds are already formed when the bulbs are planted in the fall. But sometimes those eagerly anticipated flowers are no-shows. If that's the case in your garden this spring, here are some possible reasons why.

Improper Storage
Bulbs that have been stored under conditions that are too hot and dry may fail to bloom the following spring. Tulips are especially sensitive. Bulbs ordered from mail-order bulb specialists are usually very reliable. When buying bulbs in retail stores, choose ones with the outer papery covering intact and no soft spots or mold. At home, store bulbs in a cool, dry location before planting.

Cutting Down Foliage Too Soon After Bloom
It's tempting to tidy up the garden by cutting back the leaves of bulbs after they've finished flowering. But those leaves are manufacturing food that will be stored in the bulb to provide the energy for a robust display of flowers the following spring. Let the foliage turn yellow and die down naturally. Don't braid or bind leaves together since sunlight needs to reach the leaves in order for them to produce food.

Poor Drainage
Bulbs are not garden prima donnas. They will generally tolerate a wide range of growing conditions. But one thing they can't abide is soggy soil. Add organic matter to heavy soils to improve drainage. Consider planting in raised beds if your soil is very poorly drained.

You may have planted your crocuses to enjoy their cheerful flowers, but the local squirrels probably think you did it only to provide them with tasty treats. Mice, chipmunks, and skunks also relish dining on bulbs. Daffodils and snowdrops (Galanthus) are not very palatable to these critters. If rodent damage is troublesome, try planting bulbs such as tulips in buried "cages" made of one-inch wire mesh. The bulb's shoots will grow through the openings, but the marauders will be kept out.

Then there are the critters that dine on the bulb plants after they are up and growing. I have a big problem with rabbits that seem to think that my crocuses are an all-you-can-eat buffet. They wait until the plants are blooming, then come in and eat them off as cleanly as if they were mowed. I'm afraid I don't have any magic bullet solutions for keeping pests like rabbits and deer from dining on bulb foliage and flowers. Repellents are available, but my strategy is simply to plant lots of crocuses, and hope the rabbits get full before they eat them all!

Soil Temperature
Although tulips and daffodils like it cool at fall planting time, they also do best if they have time to begin some root growth before the soil freezes. Plant when the soil six inches deep is 60 degrees or cooler, in September or October. Waiting to plant when the soil is cool is especially important for tulips; don't plant them until the soil temperature 6 inches down has fallen at least to at least 55 degrees F.

Over-crowded Bulbs
Many bulbs, especially daffodils and small bulbs, will bloom happily for years on end without needing division. But eventually the clumps can become crowded and blooming tapers off. The easiest time to separate clumps is after the flowers have faded, and the leaves are yellowing, but still visible. (You can mark the location of the clump and dig and divide in fall, but it's much easier to find the bulbs in the soil when they still have leaves attached.)

Carefully lift one clump at a time and gently separate the individual bulbs. Have some wet burlap or newspapers on hand to cover the the unearthed bulbs and keep them from drying out as you replant. When they are back in the ground at the correct depth, mulch around them and keep the soil moist until the foliage dies down naturally.

Short-lived Tulips
Unlike daffodils and many of the small bulbs that come back to bloom for many seasons, tulips are often brief visitors in our gardens. After two or three years, blossoms get smaller and the plants gradually die out. Some gardeners simply replace their tulip bulbs every couple of years -- even annually. Considering the mind-boggling number of tulip varieties to choose from, this can be a good excuse for gardeners seduced by all those appealing catalog descriptions. For more frugal gardeners, certain varieties and planting techniques can keep tulips happy longer. Soil preparation is especially important. Good drainage is essential, and soil pH should be between 6 and 7. Set bulbs deep (eight inches). Fertilize the bulbs in fall with a bulb fertilizer (while there is no top growth then, the roots are active in the soil) and again in spring just as the shoots emerge. Choose varieties that perennialize well, such as Triumph, Fosteriana and Darwin Hybrid tulips. Here are some suggestions for tulips that tend to perennialize well:

'Dreaming Maid' - Triumph tulip - soft lavender shading to white
'Don Quichotte' - Triumph tulip - deep rose shaded with purple
'Golden Apeldorn' - Darwin Hybrid tulip - pure golden yellow
'Parade'- Darwin Hybrid tulip - bright red
'Candela' - Fosteriana tulip - pure yellow

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