By Deborah J. Benoit
Forsythia in February? Impossible, you say? Not so. A vase full of flowers from the garden won’t take much more effort than harvesting some branches to force them to bloom.
A good time to take cuttings for forcing is when you’re doing your annual winter pruning. If pruning isn’t on your winter to-do list, just take a look around your yard. What trees and shrubs do you have that bloom in the spring? These set their buds during the previous growing season, so they’re already ready to bloom once spring arrives (or you fool them into thinking it has).
Choose early spring-blooming varieties for early winter forcing. Shrubs such as witch hazel (Hamamelis) and forsythia (Forsythia) are good choices. In mid-winter, you can try flowering quince (Chaenomeles), azaleas and rhododendrons (Rhododendron), crab apples and apples (Malus) or cherries (Prunus). In late-winter, lilacs (Syringa), spirea (Spiraea) and mock orange (Philadelphus) can be forced to bloom indoors.
In general, those varieties that bloom earlier in the spring can be cut and forced earlier in winter than those that bloom later in spring. All can be cut and coaxed into bloom right up to their outdoor bloom time. Imagine a vase filled with lilacs and forsythia while there’s still snow on the ground outside your window.
Since these plants are programmed to bloom once winter departs, they do need a period of cold weather. Once they’ve experienced at least 6-8 weeks of temperatures below 40 degrees, you can begin to harvest branches for forcing. Grab a pair of pruners and head outside. The best time to cut is when temperatures are mild.
Always use good pruning practices. Remember, what you cut now will affect how the tree or shrub blooms come spring, as well as future growth and form. If you’d like to know more about pruning, you’ll find helpful information at go.uvm.edu/pruning-dormant-plants.
Cut segments at least a foot or two in length, longer if you’d like a really dramatic display. More flower buds mean more flowers. While it may be difficult to distinguish between flower buds and leaf buds, in general, flower buds will be fatter, leaf buds more pointed.
Once you’ve gathered enough cuttings, bring them inside. Fill a container with warm water. Recut the ends of each branch at a sharp angle and slice vertically through the end or lightly smash it to allow more intake of water.
Remove any side branches or twigs that will be beneath the water. Then arrange the cuttings in the container.
Place the container in indirect light such as a north-facing window, away from drafts and heat sources. Be sure to change the water frequently, at least every few days, to keep it fresh.
Buds may drop if your indoor environment is very dry, so misting daily or covering the branches and container with a large, clear plastic bag can add needed humidity until the buds begin to open.
If buds do drop off, you may have taken your cuttings too soon. Don’t hesitate to try again. The later in winter and closer to nature’s bloom time, the greater the chance for successful forcing.
Above all, be patient. The process can take up to a month, sometimes longer. But as you watch, you’ll witness an early spring as the buds swell. And you’ll be rewarded with a vase full of flowers while there’s still snow on the ground outside your window.
Sometimes it’s very nice to “fool Mother Nature.”
For more information on forcing branches in winter, check out go.uvm.edu/forcing-flowering-branches. Deborah J. Benoit is a UVM Extension Master Gardener from North Adams, Mass., who is part of Vermont’s Bennington County Chapter.