University of Vermont Extension
Department of Plant and Soil Science
Winter News
Article
FORCING
FLOWERING BRANCHES
Dr. Leonard Perry, Extension Professor
University of Vermont
Trick your spring-flowering trees
and shrubs into thinking it's spring this winter, and into blooming.
This is
what you do by cutting branches and bringing indoors. The process is
called
"forcing."
Trees and shrubs, which bloom in
spring, form their flower buds the previous fall. After at least eight
weeks of
cold outdoors (under 40 degrees F), their branches are capable of
blooming if
you provide the right conditions. To make sure they receive enough
cold, don't
cut branches until after January 1 in a "normal" year or after
January 15 in a "mild" year. Branches harvested in late winter often
come into bloom indoors sooner than those harvested earlier.
Carefully prune out branches so not
to injure the plant or ruin its shape. Use sharp pruners, and cut
branches at
least 12 inches long. Select branches with a large number of flower
buds. These
are often on younger branches. Make sure you are looking at flower buds
and not
leaf buds. The flower buds are usually larger and rounder. If in doubt,
cut a
few buds open to look for leaf or flower parts inside. Branches force
more
readily if cut on a sunny afternoon or when temperatures are above
freezing.
Bring the cut branches indoors,
placing the stem ends immediately in water. If branches are in a
bucket, mist
them frequently the first few days or enclose in a plastic bag out of
direct sun. If possible,
submerge the whole stems in water, such as in a bathtub, overnight.
This allows
buds and stems to
quickly absorb water and begin to break dormancy.
The old recommendation was to smash
the stem ends with a hammer to improve water
uptake by the
stems. Sometimes this works, but it may have the opposite effect if
stems are
mashed too hard. And the mashed ends may make the water more dirty,
which will
decrease water uptake. The best method is to make a slit or two in the
bottom
of the stem before placing in the water, such as in a cross or star
pattern as
viewed from the bottom.
Keep branches in a bucket of water
in a cool area (60 to 65 degrees F). Warmer temperatures cause buds to
develop
too rapidly and not open properly. Change the water every 2 to 3 days
to ensure
it stays clean.
Low humidity, common in many homes
in winter, also may cause buds to fall off. Try to keep branches near a
humidifier, or misted. Direct sunlight also may cause buds to fall, so
keep in
bright but indirect light.
Once the flower buds show color, the
branches can be used in arrangements. Use of floral preservatives,
available at
many garden stores and florists, may increase the life of the branches
(the
"vase life"). Once again, keep stems in bright, but indirect, light.
Moving arrangements to a cool location at night (40 to 60 degrees F)
will help
them last longer.
For cutting as early as January,
consider the Cornelian Cherry (yellow flowers, 2 weeks to force into
bloom),
Forsythia (yellow flowers, one to 3 weeks to force), Witch Hazel
(yellow
flowers, one week to force), Poplar (long lasting, drooping flowers
called
"catkins," 3 weeks to force), and Willow (catkins, 2 weeks to force).
In February, consider these same
plants plus the Red Maple (pink to red unusual flowers followed by
leaves, 2
weeks to force), Alder (catkins, one to 3 weeks to force), Amelanchier
or
Serviceberry (white flowers, one to 3 weeks to force), Apples and
Crabapples
(white, pink and red flowers, 2 to
4 weeks to force with doubles slower than singles), Birch (long lasting
catkins, 2 to 4 weeks to force), Quince (red to orange flowers, 4 weeks
to
force), Cherries (white and pink flowers, 2 to 4 weeks to force),
Rhododendrons
and Azaleas later in the month (many colors, 4 to 6 weeks to force),
and Pussy
Willow (well-known furry flowers, one to 2 weeks to force).
Then in March, consider cutting
branches of Hawthorns (white, pink or red flowers, 4
to 5 weeks to
force) but be careful of the thorns, Deutzia (white flowers, 3 to 4
weeks to
force), Honeysuckle shrub (white to pink flowers, 2 to 3 weeks to
force),
Mockorange (white flowers, 4 to 5 weeks to force), Oaks (catkins, 2 to
3 weeks
to force), Lilacs (many colors, 4 to 5 weeks to force), and Spirea
(white
flowers, 4 weeks to force with double flowers lasting longer).
Cut various branches, at various
times, for a succession of blooms and color indoors during our long
winters.
It's one way to help spring come early in the North!
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Perry's Perennial
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