Pruning Deciduous Trees and Shrubs
Contact: Diane Relf, Extension Specialist, Environmental Horticulture,
Virginia Tech
Publication Number 426-709, Posted July 1997
Table of Contents
Introduction
Reasons for Pruning
Tools
Timing
Cuts
Shrubs
Hedges
Trees
Pruning is essential for attractive, healthy trees
and shrubs and improves the quality of flowers, fruit, and foliage. The
best way to avoid difficult pruning jobs is to plan ahead; select plants
that will fit available space after the plants have matured to their maximum
size.
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Reasons for Pruning
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Training the plant: Some pruning may be necessary at the time of planting
to shape your tree or shrub. Broken, crossing, and pest- infested branches
should be removed, but avoid excessive pruning at transplanting as it tends
to retard plant growth and inhibit survival.
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Maintaining plant health: Pruning is vital for removing dead, dying, or
diseased wood. Any dying branch or stub can be an entry point or build-up
chamber for insects or diseases which can readily spread to other parts
of the plant.
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Improving plant quality: Pruning reduces the amount of wood in trees and
shrubs, and this diverts energy into the production of larger, though possibly
fewer, flowers and/or fruit. Properly timed pruning will increase the production
of wood that will hear flowers, improving the quality of fruit, foliage,
and stems as well.
Regular pruning is often employed to restrict plant growth where space
is limited. To reduce unnecessary labor, however, plants should be selected
that will not exceed allotted space.
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Tools
Choosing the proper tools is important for successful pruning. For a branch
one-half inch or less in diameter, small hand pruners (a) are best. For
branches up to 2 inches, use long-handled loppers (b). Hard-to-reach cuts
require pole pruners or pole saws. Use manual hedge shears or power shears
for formal hedges. Hand pruning saws (c) are useful when branches are close
together. Disinfect tools with alcohol or chlorine bleach diluted in water
(1:9) after each cut on diseased wood.
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Timing
Most pruning is done in late winter or early spring to give the maximum
time for the wounds to heal. However, to get the best flowering from plants
that produce blooms in the spring, prune soon after the flowers die. Flower
buds for the next year will develop on new growth during the summer. Summer-flowering
plants develop flower buds on new shoots growing in the spring. Consequently,
these plants should be pruned after the coldest part of winter. Dead or
diseased wood should be removed whenever the problem is noticed.
Begin pruning at planting to train the plant and avoid large pruning
jobs later. Trim damaged roots and rubbing branches. Plants purchased from
a reputable nursery were pruned as they grew during production, and should
require little or no pruning when transplanted to your landscape.
Evergreens don't need as much pruning as deciduous plants and should
not be cut back at planting.
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Cuts
Heading hack, or topping, cuts remove part of a limb or branch. They
induce side buds to sprout and can he used to alter the shape of the plant.
Make the cut just above a healthy bud, pointing in the direction you want
the branch to grow. Make cuts slanting to promote healing and prevent the
collection of water on the cut. Thinning cuts remove entire branches at
their junction with another branch or the trunk, reducing the number of
interior limbs. This opens the plant to sunlight and air and can reduce
overall size.
Most plants respond best to selective pruning-a combination of thinning
and heading cuts. This is healthier for the plant and gives a more natural
appearance.
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SPECIAL CONSIDERATIONS
Shrubs
Renewal pruning is used on multiple-stemmed plants like forsythia. Young
growth produces more vigorous flowers, so each spring after flowering,
remove one third of the oldest and tallest stems near ground level to encourage
development of new stems.
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Hedges
A natural shape is best for plants. Shearing formal hedges causes vigorous
growth on the outside which shades the interior, leaving a "dead zone"
that can't produce new shoots. If you must shear, make the hedge wider
at the bottom and sides slanting. Thin out individual branches to open
the plant to sunlight.
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Trees
Never top, or dehorn, a tree, where all branches are cut close to the trunk.
This is unhealthy for the tree and, if the tree survives, a heavy flush
of vertical suckers will develop.
Remove limbs with angles of less than 30 degrees from the trunk. If
not removed, they may split as the tree grows. A branch should be cut flush
with the branch collar, not the trunk. The branch collar is a usually swollen
area where the branch joins the trunk. It contains tissue with a chemically
protective zone which speeds recovery.
To protect understory shrubs, and for your own safety, tie the branch
to a stronger, higher branch. Use three cuts (see illustration) to remove
the branch as follows:
1) Make a small cut on the underside of the branch about 6 to
12 inches away from the collar and one third of the way through the branch.
This prevents the bark from peeling.
2) A little farther out from the first cut, cut down through
the branch to remove the entire limb.
3) Finally, cut at branch collar to remove the stub. File any
ragged edges from the stub.
Research shows that the branch collar is more effective against decay than
pruning sealers, which may actually slow healing.
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For more information on selection, planting, cultural practices, and environmental quality, contact your local Virginia Cooperative Extension Office. If you want to learn more about horticulture through training and volunteer work, ask your Extension agent about becoming an Extension Master Gardener. For monthly gardening information, subscribe to The Virginia Gardener Newsletter by sending your name and address and a check for $5.00 made out to "Treasurer, Va. Tech" to The Virginia Gardener, Department of Horticulture, Virginia Tech, Blacksburg, VA 24061-0349. Horticultural information is also now available on the Internet by connecting with Virginia Cooperative Extension's server at www.ext.vt.edu.
The original development of this series was funded by ESUSDA Smith Lever 3(d) National Water Quality Initiative Funds and the Virginia Department of Conservation and Recreation, Division of Soil and Water Conservation.
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