Forcing Flowering Branches

By Dr. Leonard Perry, Extension Professor
University of Vermont

 
Trick your spring-flowering trees and shrubs into thinking it's spring this winter, and into blooming. This is what you do by cutting branches and bringing indoors. The process is called "forcing."

Trees and shrubs, which bloom in spring, form their flower buds the previous fall. After at least eight weeks of cold outdoors (under 40 degrees F), their branches are capable of blooming if you provide the right conditions. To make sure they receive enough cold, don't cut branches until after January 1 in a "normal" year or after January 15 in a "mild" year.

Carefully prune out branches so not to injure the plant or ruin its shape. Use sharp pruners, and cut branches at least 12 inches long. Select branches with a large number of flower buds. These are often on younger branches. Make sure you are looking at flower buds and not leaf buds. The flower buds are usually larger and rounder. If in doubt, cut a few buds open to look for leaf or flower parts inside.

Bring the cut branches indoors, placing the stem ends immediately in water. If branches are in a bucket, mist them frequently the first few days. If possible, submerge the whole stems in water, such as in a bathtub, overnight. This allows buds and stems to quickly absorb water and begin to break dormancy.

The old recommendation was to smash the stem ends with a hammer to improve water uptake by the stems. Sometimes this works, but it may have the opposite effect if stems are mashed too hard. And the mashed ends may make the water more dirty, which will decrease water uptake. The best method is to make a slit or two in the bottom of the stem before placing in the water, such as in a cross or star pattern as viewed from the bottom.

Keep branches in a bucket of water in a cool area (60 to 65 degrees F). Warmer temperatures cause them to develop too rapidly and not open properly. Low humidity, common in many homes in winter, also may cause buds to fall off. Try to keep branches near a humidifier, or misted. Direct sunlight also may cause buds to fall, so keep in bright but indirect light.

Once the flower buds show color, the branches can be used in arrangements. Use of floral preservatives, available at many garden stores and florists, may increase the life of the branches (the "vase life"). Once again, keep stems in bright, but indirect, light. Moving arrangements to a cool location at night (40 to 60 degrees F) will help them last longer.

For cutting in January, consider the Cornelian Cherry (yellow flowers, two weeks to force into bloom), Forsythia (yellow flowers, one to three weeks to force), Witch Hazel (yellow flowers, one week to force), Poplar (long lasting, drooping flowers called "catkins," three weeks to force), and Willow (catkins, two weeks to force).

In February, consider these same plants plus the Red Maple (pink to red flowers followed by leaves, two weeks to force), Alder (catkins, one to three weeks to force), Birch (long lasting catkins, two to four weeks to force), Quince (red to orange flowers, four weeks to force), Cherries (white and pink flowers, two to four weeks to force), Rhododendrons and Azaleas later in the month (many colors, four to six weeks to force), and Pussy Willow (well-known furry flowers, one to two weeks to force).

Then in March, consider cutting branches of Hawthorns (white, pink or red flowers, four to five weeks to force), Honeysuckle shrub (white to pink flowers, two to three weeks to force), Apples and Crabapples (white, pink and red flowers, two to four weeks to force), Mockorange (white flowers, four to five weeks to force), Oaks (catkins, two to three weeks to force), Lilacs (many colors, four to five weeks to force), and Spirea (white flowers, four weeks to force).

Cut various branches, at various times, for a succession of blooms and color indoors during our long winters. It's one way to help spring come early in the North!

Source: UVM Extension