University of Vermont Extension
Department of Plant and Soil Science

News Article


By Dr. Leonard Perry, Extension Professor
University of Vermont


Pruning is perhaps the most intimidating of all gardening tasks for many homeowners, and therefore, probably one of the most neglected. But there are a lot of good reasons why you should prune trees and shrubs.

Obviously, if a tree limb is threatening to fall on your house or is left dangling after a storm, you'll want to remove the dead or damaged wood as soon as possible. But judicious branch and limb cutting also helps reduce the likelihood of disease and insect infestations; shapes plants and controls their growth; and repairs damage. In addition, pruning improves both the yield of fruit trees and the aesthetic value of ornamentals.

Knowing when to prune is just as important as knowing why. Here are some general guidelines:

DECIDUOUS TREES (those losing leaves in winter)--March or April (before leaf). Spring flowering trees should be pruned after flowering.

DECIDUOUS SHRUBS--Prune spring-flowering shrubs soon after bloom. Summer-flowering shrubs, such as hydrangea, should be pruned in early spring (buds have not formed yet).

EVERGREEN TREES--usually do not require pruning except for shaping.

EVERGREEN SHRUBS--The best time to prune most junipers, yews, hemlocks, and arborvitae is late winter to early spring. Pruning may be required in mid-summer to keep vigorously growing plants at the desired size. Wait until after flowering or, if the plant produces berries, after berries fall.

FRUIT TREES--in late winter (March) while tree is still dormant and before buds begin to swell.

To prune you will need sharp, well-maintained tools. Buy the highest quality tools your budget allows. They may cost a little more, but they keep an edge longer than cheaper models.

Your basic cutting tool should be a pair of pruning shears, suitable for cutting branches of up to three-fourths inch in diameter. Newer tools are ergonometrically designed to prevent undue stress on hands and wrists. You also may want to invest in a pair of long-handled lopping shears for cutting branches up to one or two inches in diameter and a pruning saw for cutting larger branches. An extension-handled pruning saw will be useful for cutting branches high overhead.

The first step in the pruning process is to cut out any broken, dead, or diseased wood. Dead wood left on the plant eventually rots, introducing decay organisms into living tissue.

Here are a few more pruning basics to remember:

--Cut out branches that rub against other branches or limbs.

--Cut branches at the point where they join another branch or the trunk. When there's a choice, cut branches that join at a narrow angle rather than those that join with a wide angle. Wide-angled branches are stronger.

--Do not cut limbs flush with the trunk. Leave the swollen joint or branch collar intact. "Painting" pruning wounds with latex paint, grafting compound, or wound sealant is not necessary and does not aid proper healing.

--Prune a little at a time. Heavy pruning stresses the tree.

--When pruning fruit trees, keep in mind that young trees require severe pruning to create proper branch structure for the tree to bear fruit as it gets older. In later years, prune lightly--unless you are revitalizing an abandoned tree--to maintain the fruiting and shape of a tree.

--Always disinfect pruning equipment with alcohol before using it to prune another tree or shrub. Disinfecting tools helps reduce the spread of disease.

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