Spring preview: Forcing flowers into bloom

Forsythia is easy to force into bloom. — kkmarais/Creative Commons

"Forcing" plants into premature bloom has always sounded a little coercive to me. It prompts an image of a bound and gagged plant helpless in the hands of a desperate gardener brandishing a sharp pair of pruners: "Bloom, or else!"

It is the proper horticultural term, though, and in practice forcing is kinder and gentler than all that. What we're really talking about is coaxing branches and boughs of common backyard plants into life indoors, weeks before they start to stir outside in the cold.

This is a perfect sport for late winter or early spring when forcing is most successful. It's really a bit of everyday magic: Gather some bare sticks, bring them into the warmth and watch them unfurl tiny green leaves and delicate flowers.

The closer to the natural time of flowering you cut branches, the more quickly they will break dormancy indoors. For best results, collect material on a day when temperatures are above freezing.

Forsythia is the classic forcing material and among the easiest to bring to bloom. Other good subjects to cut in late February or early March include pussy willow, red-twig dogwood, quince and spirea. Wait a few weeks and you can try branches of peach, pear, crab apple and cherry trees, mock orange and wisteria.

Don't underestimate the charm of tree branches and new leaves that aren't ordinarily considered decorative. Beech twigs bear long, drooping flower spikes, red maples have curious orange-red flowers and weeping willows yield supple wands of golden-green foliage. For the unusual, ask around to locate the sweetly fragrant winter honeysuckle (a bush, not a vine) or bittersweet (a vine, not a bush), which has curling tendrils of tender green.

Pussy willows are another favorite forcing subject. — Uwe Hermann/CC

Cull branches of 10 to 24 inches, pruning with an eye to maintaining your shrubbery's graceful, natural shape. Place branches in cold water in a dim place for a day or so to avoid shocking them. Then cut stems again on an angle and make a few slashes vertically up the stem to improve water absorption. If you want to speed to loosening of buds, you can even submerge your branches in a tub of water for a couple of hours, but this isn't strictly necessary.

Keep your cuttings in a cool location out of direct sun and then just wait, refreshing the water as needed. In 10 days to four weeks (depending on species) buds will fatten up and start to show color. That's when you can move the branches into a bright, warm location to prompt blooming, the final chapter of the process.

The rewards of this bit of plant persuasion are quite uplifting and you'll want to show off your handiwork in a conspicuous location. The most common reaction I hear to my gaudy, bawdy forced forsythia whips is an incredulous "Are those real??!!" Yup.

Display your flowering branches with or without more conventional companions. Try pink florist tulips with forced purple-leaf plum. Or forsythia with yellow and white daffodils, soaking the dafs separately in cold water first to counteract sap that can cause other flowers to wilt. If top-heavy branches threaten to topple a favorite vase, fill it half-way with sand or pebbles before adding water.

Above all, experiment with what you have on hand and don't be discouraged if some plant material doesn't respond well. Forcing is free, easy and fun -- and you just might conjure up a touch of spring to tide you over until the real thing comes along.