Sunday, October 7

Forcing bulbs the easy way

Spring-blooming bulbs like these white hyacinths are easy to force at home. Other easy-bloomers include Triumph, Single Early, Double Early and species tulips, crocuses, grape hyacinths, amaryllis, miniature narcissus, paperwhite narcissus and dwarf iris. Dutch iris and taller daffodils, narcissus and tulips can be more difficult, though, because they are prone to stretching.

Even as the world above them is suspended in icy slumber, bulbs planted in fall are growing. Then, once winter loosens its grip and the days begin to lengthen, they emerge into a riotous show of spring color.

But why wait for spring? By preparing spring bulbs for forcing now you can enjoy those glorious blooms during winter's dreariest days. This age-old technique gives the savvy gardener a sneak peak at spring and is also a great source of gift plants for special friends. Best of all, successfully forcing bulbs is easier than you might think.

One of the first things we need to tackle, though, is the word itself -- forcing. It sounds pretty harsh, even cruel, while in reality the gardener is merely coaxing the bulbs out of their slumber; first by simulating winter conditions (to induce root, shoot and bud development), and next by gradually exposing the "winterized" bulbs to increased light and spring-like temperatures.

In nearly all cases, potted bulbs will require cold, but not freezing, temperatures. Older gardening references often detail elaborate procedures that require the gardener to excavate enormous trenches -- at least six inches deeper than the local frost line -- pack spring bulbs edge to edge in a bed of wood ashes, and then cover them with marsh hay and boards (for easy removal on snowy days). But this far into the current millennium, who is really going to bother with all that? Most of us don't have the room or the time.

A far easier method is to place a few pots in the refrigerator in early fall (now!) and let them sit there through the holidays. Shortly after the New Year, you can begin removing the pots as desired to watch them grow and bloom in a sunny window or well-lit room. The procedure is roughly the same for all hardy bulbs, but tender ones such as hippeastrum (amaryllis), and Narcissus papyraceus/tazetta cultivars (paperwhites) have the added advantage of not requiring a cold period. But feel free to experiment with different varieties. Let both your successes and your failures be your guide. And most of all - have fun!

Hints for successful forcing:

1. Use a good quality potting soil, not topsoil or garden soil.
2. The most successful plantings are composed of a single variety, leave mixes to the garden.
3. For tulips, choose cultivars from shorter classes (species, Greigii, Single Early, Double Early, Triumph and others) for the best finished appearance. Taller types can stretch and flop over.
4. Likewise for lilium (true lilies), use some of the readily available shorter cultivars, which are particularly prominent in the Asiatic and Oriental classes.
5. Barely cover "noses" of bulbs with potting soil -- forget about the recommended depths for outdoor planting.
6. Water newly planted bulbs thoroughly.
7. Cover pots with plastic wrap, rubber band the edges around the pot rim to prevent snagging the plastic on other occupants of the fridge, and punch three to five holes in the top of the plastic to admit air.
8. Check for drying periodically and water as needed.
9. Do not "short-sheet" the cooling time -- improperly cooled bulbs may produce malformed stems and blooms.
10. Keep pots in subdued light for the first week out of the refrigerator to promote initial shoot elongation. After the first week, move to a brighter location such as a cold window. Keep as bright and cool as possible to prevent excessive stretching.
11. Some bulbs may need support, especially paperwhite narcissus, Dutch iris, some amaryllis, and some lilium.
12. Be creative with decorative containers, moss and accessories when displaying bulbs in growth and bloom.
13. Bulbs can be transplanted to normal depths outdoors after the weather settles in spring.
14. Except for amaryllis, which can be grown in the same pot from year to year, absolutely do not force the same bulbs a second time.

*Web Extra: A guide to forcing bulbs in your refrigerator

A lifelong gardener, Robert F. Gabella has been involved in the horticulture industry since 1983. With an AAS in ornamental horticulture and a BA in business management, Bob is an Illinois Certified Nursery Professional, an independent consultant, hybridist, writer and photographer. He also tends prize-winning gardens at his Villa Park home.