Jumpstart spring indoors

Horticulture Hints

Spring. Are you counting down the days? Why not bring a breath of spring indoors by forcing flowering branches.

The term “forcing” in horticulture terms is a method to speed up plant growth by artificially controlling heat and light to encourage early flowering. With branches from flowering trees and shrubs, this is done by cutting branches and bringing them indoors to flower.

Select healthy branches with many plump buds. Be sure to keep the form of the tree or shrub in mind when cutting, as not to disfigure the plant. Cut just above a side bud at a 45 degree angle, as not to leave a stub, around 12 to 18 inches long is a good length. Use a sharp knife or pruners when cutting branches, and place ends immediately in a bucket of water.

To encourage water uptake, make an inch long split in the bottom of each branch. Soaking branches in the bathtub overnight will help stems to more quickly absorb water and will also aid buds to break winter dormancy sooner. If branches are cut when temperatures are below freezing, be sure to use cool water to prevent the buds from opening too soon. A warm sunny winter day is the best time to cut branches for forcing, for both you and the branch.

Time to flowering indoors depends on the plant. Pussy willow branches take one to two weeks; cherries and crabapples will take two to four weeks; while serviceberry and forsythia take one to three weeks to bloom.

Low humidity and direct sunlight may cause the buds to fall off, so place branches near a window with bright, but indirect light. Keep branches away from heat sources (around 65-70 degrees is best) and mist often or place on a pebble tray of water to help with humidity.

Remember to change vase water every few days to help prevent bacteria build-up, which can clog the branch vascular system and inhibit water uptake.

Did you know? Spring-flowering trees and shrubs set their flower buds the previous fall. This is why it is recommended to wait to prune woody spring-flowering plants until after they have bloomed. For example, if a lilac bush is pruned before it blooms, you would be cutting off all the blooms for the year.

Horticulture Questions? Contact McCormick at yvonne@iastate.edu for information or advice.

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