Ask the master gardener: ‘Force’ blooms for early color as winter wanesBy: Trish Grenfell, Placer County Master Gardener
Question: I vaguely remember something about “forcing” flowers so that we can have some early spring indoors during the gray, drab winter. Can you explain?
Answer: Forcing refers to the practice of cutting branches from spring blooming, deciduous trees and shrubs, bringing them indoors and providing the right conditions to produce
Flower buds are usually set during the previous growing season, but they must experience Six to eight weeks of night temperatures below 40 degrees (dormancy period) before they are capable of blooming. Here in the Auburn area we normally achieve enough of those low temps by February.
And it so happens that late winter is also an ideal time to prune these trees and shrubs. Following good pruning principles (http://homeorchard.ucdavis.edu/The_Big_Picture/Pruning_&_Training/), make your cuts in the warmest time of the day (more sap in the branches). Select young branches at least 12 inches long (most will be longer) with a large number of flower buds. Cut into some buds if you can’t tell the difference between flower and leaf buds.
Bring your choices indoors and place stem ends in water immediately. University of Nebraska Extension recommends submerging the branches in room temperature water overnight in a bath or wash tub. This soak hastens the forcing process by allowing the buds to begin to break dormancy.
Next place the branches in a bucket of room temperature water and place it in a room with coolish temperatures (50-60 degrees) and bright light, but no direct sun. Higher temperatures may shorten this process, but flower quality will likely be sacrificed. Mist the branches occasionally to increase humidity. And remember to change the water every few days to prevent it from becoming foul.
A floral preservative will also help control the bacteria buildup. The closer to spring that branches are forced, the shorter the time required until bloom.
When the flower buds show color, remove the branches and arrange for display. This eliminates moving and arranging the branches covered with flowers — which may harm the flowers. Keep the arrangement in a bright but not sunny location. The flowers will last longer if they are moved to a cool (40-60 degree) location at night. Branches forced for foliage will last even longer.
Top plant choices always include forsythia which readily forces. Other suitable plants are pussy willow, redbud, quince, dogwood, hawthorn, crabapple, witch hazel, beautybush, magnolia, apple, cherry, pear, spirea, and lilac.
Have gardening questions? Call the Master Gardener hotline at (530) 889-7388.