Forcing Forsythias Indoors

Before too long, some horticulture enthusiasts will be thinking about harvesting branches of flowering shrubs and bringing them indoors to force into bloom. Cold followed by a warm spell is the combination that sets buds to swelling. Cold weather followed by warmth breaks the genetically-designed and controlled dormancy that gets them through cold weather without harm.

Forsythia is the first flowering plant ready for blooming, and the easiest to force. During the late summer, the blossom and leaf buds were fully formed and ready to go. A cold spell in the fall followed by a warm period will cause it to rebloom. A few little yellow flags pop out, wave in the autumn breezes, discover winter is coming and catch cold. But if you cut those branches and take them indoors for forcing in the fall before a chilling period, even well-budded forsythia won’t bloom, so don’t let that tempt you.

Here in Zone 7, the forsythia can be ready to force in late January. You know how ready a branch is for forcing by the amount of swelling in the buds. The larger the buds, and the closer they are to flowering outdoors, the more likely they will quickly bloom indoors. The smaller the buds, the longer they’ll take to force into bloom indoors. Depending upon that size, it takes one to three weeks to force forsythia. The other flowering shrubs need two to five weeks.

The best forsythia branches for forcing are those at the top of the plant, the ones studded with closely spaced buds. Choose the branches that have the largest buds (they’re the flower buds). Cut the stems at a long slant and stand them in cold water in a cool place for two days. Then re-cut the stems and arrange them in a large pitcher of warm water in a sunny window.

In a few weeks, these very small yellow flowers will open, and sometimes while the flowers are still there, a few small pale green leaves open out, but usually the leaves won’t appear until the flowers fade. Left in the water for many more weeks, forsythia branches may root: planted, they usually will grow into shrubs.

Forsythia is the easiest to force and the most satisfying because it puts out the most flowers. Branches of almost any shrub that flowers in spring can be forced into bloom indoors, including pears, cherries, and dogwoods. The flowers on forced crabapple and quince are sparse, but exquisite. Pussy willows can be forced in February, and they’ll bud in just a week or two if you remove the bud scales. When the blossoms are fully developed, remove the branches form the water or they’ll root and drop their flowers. Spirea can be forced too, and so can lilac, but forced lilacs are poor pale things that always make one wish they’d left them on the shrub to bloom.

Just one branch of cherry blossoms alone in a vase in late winter has an extraordinary impact. And those great curved whips that forsythia shrubs throw out are beautiful when forced into bloom and combined with sprays of deep pink miniature carnations and one or two branches of hemlock, juniper, or nandina. Flowering quince or dogwood combined with trailing stems of asparagus fern and huge apricot and pink tulips make an exquisite bouquet.

For additional Horticulture related information contact your local Cooperative Extension Service. The University of Arkansas System, Division of Agriculture is an equal opportunity/equal access/affirmative action institution.

Sherri Sanders
County Extension Agent - Agriculture