Green Industry Resources
Hort Update- Seasonal Information for the Green Industry
Forcing Spring Flowering Branches
Branches from flowering trees and shrubs can be forced into bloom easily and inexpensively, bringing a little bit of the outdoors and some very welcome color inside during the late days of winter.
Trees and shrubs that bloom early in spring, form their flower buds the previous fall before dormancy. After at least 8 weeks of cool weather (under 40 degrees) the branches are ready to overcome dormancy and are capable of blooming. By undergoing spring-like temperatures and moisture, the flowers are forced open. Successful forcing depends on the type of plant, cultivar, stage of dormancy, and temperature.
Carefully prune branches from the parent plant, making sure not to injure or ruin the shape of the plant. Select branches at least 12 inches long, and be sure to use sharp pruning shears to minimize damage.
Select branches that are well budded, or that have a large number of flower buds. Flower buds are usually larger and rounder than leaf buds. Best results will occur with younger branches because they have more flower buds. If there is a question cut a few buds open and look for flower parts. Some fruit trees bear flowers on short fruit spurs. Watch for these on apples, pears, and ornamental crabapples.
Forcing the Branches
After cutting the branches, bring them indoors and place the stem ends in water immediately. If possible, totally submerge the branches in room temperature water overnight. A wash tub or bathtub works well for this. This soaking allows the branches and buds to begin to break dormancy. If soaking is not possible, place the cut ends of the branches directly into a bucket of water and mist the branches frequently the first few days. A piece of damp burlap should be wrapped around the branches, or place a plastic bag over the branches to help maintain high humidity.
After spraying or soaking, the branches are ready for forcing. Place the branches, still in their bucket of water, in a cool place, approximately 50 degrees. Higher temperatures will cause the buds to develop rapidly, but size, color, and quality may be sacrificed. Along with higher temperatures often goes lower humidity that may cause the buds to day out and fall off.
Branches need light for forcing, but not direct sunlight. Heat from direct sun is too intense. To help the buds open and keep them from drying, mist the branches occasionally during the forcing period. The closer to spring that branches are forced, the short the time required until bloom.
Change the water in the buckets often to prevent it from becoming foul.
Enjoying Your Flowers
When the flower buds are well developed and showing color, remove the branches from the buckets and arrange for display. Branches that are removed from the buckets at this stage are less likely to have bruised and broken flowers. Arranging the branches at this stage also allow the enjoyment of watching the flowers open. The branches should be kept in a bright, but not sunny location. They will last longer if they can be move to a cool (40-60 degree) location at night.
Plants for Forcing
Plants suitable for forcing include serviceberry, redbud, quince, dogwood, hawthorn, forsythia, witch hazel, beautybush, honeysuckle, magnolia, apple, mockorange, cherry, pear, pussy willow, spirea, lilac and wisteria.