How do you force branches of spring-flowering trees and shrubs indoors?
Forcing can be done as soon as the buds start to swell. Forsythia and pussywillow can be forced as early as February. It's best to wait until March for more difficult-to-force ornamentals, such as crabapples, magnolias, and redbuds.
Select branches containing round, plump buds (narrow, pointed buds are usually leaf buds; flower buds are generally larger and have a more rounded shape). Make clean, slanting cuts 1 to 2 feet from the tips of branches with a sharp hand shears. Selectively remove branches that won't destroy the natural shape of the plant. If pruning fruit trees in late winter, gather some of the pruned material for forcing indoors. If possible, collect branches when temperatures are above 32 degrees Fahrenheit. If the plant material is frozen when collected, submerge the branches in a tub or pail of water for a few hours.
Later, set the branches in a tall container of water and place in a dimly lighted, cool (60 to 65 degrees Fahrenheit) location. Spray or mist the branches two or three times a day to prevent the buds from drying out. Also change the water in the container daily during the forcing period. Daily changes of water should inhibit the growth of bacteria and fungi which could interfere with the absorption of water by the branches. When the flower buds begin to open, move the branches into a bright room. Keep the flowering branches out of direct sunlight and in a cool location to prolong the bloom period.
The time period required to force branches into bloom depends upon the plant species and collection date. Forsythia and pussywillow generally take only one to three weeks to force. Magnolia branches may take three to five weeks. The closer it is to the plant’s normal outdoor flowering period, the less time it will take to force the cut branches indoors.