In the dead of winter, it's hard to imagine the stage is already set for flowering trees and shrubs to burst into bloom. In fact, after six to eight weeks of 32° to 45° F outdoor temperatures (by January in most areas), trees and shrubs have met their dormancy requirements, and if the weather warms up, they'll start to grow and bloom. Depending on where you live though, you'll likely have to wait at least a month or two for real spring to arrive.
But if you're an impatient gardener who needs a fix of flowers to offset the drab colors of winter, you don't need to go to the florist -- just step outside. By pruning branches from many common deciduous trees and shrubs, you can create beautiful indoor bouquets to serve as harbingers of spring.
Most northern gardeners know about forcing branches of apple, cherry, forsythia, and plum trees and shrubs indoors, but numerous other kinds of branches can also be forced not only for their beautiful flowers but for their interesting young leaves. Japanese and red maples have colorful, delicate young leaves. Poplars and birch produce chenille-like catkins (scaly, often pendulous flowers) that make for unusual arrangements. To scent your room, you can even try forcing fragrant flowers such as lilacs or honeysuckle.
However, forcing is not as simple as wandering out in January and pruning every shrub or tree in sight. Most trees and shrubs force best when pruned about six weeks before their natural bloom time. This time may be shorter in warm-winter areas, in microclimates, or for individual trees.
Swelling of the buds is also an indicator for when to cut branches; check buds weekly starting in early January. In cold-winter areas such as USDA Hardiness Zones 4 through 6, you can cut early-blooming shrubs such as cornelian cherry, forsythia, and vernal witch hazel starting in mid-January. Cut later-flowering trees and shrubs such as apple, dogwood, and magnolia between February and early March. In warm-winter areas, such as zones 7 and 8, forcing branches is not as popular because winters are short and many trees and shrubs naturally bloom early. However, to get a few weeks' jump on the season, in late January and early February you can cut branches of redbud and other trees that normally bloom in late February and March.
To force branches of your favorite trees and shrubs, select and prune 1- to 2-year-old stems, which usually have the most flower buds. Branches should be 1 to 2 feet long, and the cut should be flush with a larger branch or the trunk so as not to deform the plant or provide easy access for insects and diseases. Try to select branches with many flower buds, but also keep in mind the overall shape of the tree or shrub when making your cuts. Generally, flower buds are fatter and more rounded than leaf buds. If you can't tell which is which, dissect a few buds and look for the flower parts inside.
Bring the cut branches indoors and submerge them overnight in room-temperature water. This helps the branches and buds take up the water they need to force the flowers to open. The next morning, recut the bottoms and make inch-long vertical slits in the cut ends to help the branches take up water. Place branches in a vase of warm water in a 60° to 65° F bright room away from heaters and direct sun. In general, the brighter the room, the truer the colors and stronger the fragrance, though blossoms will never look and smell exactly the same as they do outdoors. Group branches near other houseplants and mist them daily to keep the humidity high. Depending on the kind of branches and when you cut them, flowers will begin appearing in a few weeks. The closer to their natural flowering time the branches are forced, the sooner the blooms will appear. Once open, misted flowers and catkins can last for a week if kept in a cool room, and some branches with leaves will last up to two weeks.
Article published on June 23, 2008.