While for some this may be the season to cut down a Christmas tree, for those who have deciduous (leaf-dropping) trees in their yard, this is a good season to prune. Maples, oaks, birches, lindens, hawthorns, flowering crabapple trees, particularly if they are 3-10 years old, all can benefit from cutting out, trimming up and pruning back. And doing it now, from late fall through the winter, as the tree is dormant and branches are easily seen, makes a lot of sense.
A short word, first, about pruning other shrubs and trees. For lilacs, forsythia, azalea, hydrangea, spirea and other early-flowering shrubs, wait. Take off the dead blossoms and dead branches any time, but leave the rest of the pruning until after the plants have bloomed, so as not to disturb any bud-making that is taking place now. For raspberries, take out the spent dead canes now or in the very early spring, during dormancy, and thin the others to 3-4 stems per foot. For evergreen trees, little to no pruning is needed.
Now, back to the deciduous landscape trees. Start with the reasons, and time, for pruning. The first is plant health: prune when the tree is dormant, to guard against the threat of pest and fungal diseases, and to avoid interfering with growth. In addition, pruning, far better than chemicals, removes diseased branches, helps prevent infection, assists in pest management, now and in the future, and increases vigorous growth.
The second reason to prune is the safety of those walking beneath the branches, the protection of property and the need to stay away from electrical wires. And third, pruning can add to the look you want — the ornamental value — controlling a tree’s size, balance, and shade.
Three basic tools, and two basic guidelines, are needed for the task. The tools are pruning shears, for branches up to three-fourths inches; lopping shears, for branches up to one and a half inches; and a curved pruning saw, some of which are equipped with a long pole, for thicker branches.
And the guidelines? Look, and don’t hurry. Check out the tree from all angles, and often, in the course of pruning. And go slowly, one decision and cut at a time, observing and evaluating as you work. Remember that pruning smaller, rather than larger, stems will make it easier for the tree to heal.
So which branches should be pruned? For starters, any that are dead or diseased. Then, if the trunk, or leader, has forked into two, take one out, the one whose removal will do the least harm to the tree, usually the smaller limb. Next, remove suckers (those small upward stems at the base of the tree) and watersprouts (those fast-growing vertical stems growing up from the branches, common in fruit trees). In addition, take out branches that are heading back toward the tree, or growing downward. If branches are crossing each other, remove one of them; their rubbing together could damage the bark and cause infection.
Prune some branches that are limiting the light and strength of the tree. Open up the canopy and thin out dense areas. Aim to leave limbs that are evenly spaced around the tree and 8-12 vertical inches apart, and be aware that wide angles from the trunk are stronger than narrow ones. And to encourage a particular young branch’s direction, cut back to just above the bud.
When removing a branch, cut clean and sharp, and just beyond the wrinkly “collar” bark that joins the branch to the tree (the bark ridge and branch collar). This will allow the tree to close off the wound made by cutting, and help the tree to stay healthy. For large limbs, make three cuts: one upward, most of the way through, a foot or so from the trunk; the second downward, a few inches beyond the first; the last, likely after the limb has fallen from the first two, just outside the trunk.
Pruning is something of an art, but a satisfying one. For the health of the tree, for safety and for beauty, it is a worthwhile endeavor. The University of Maine Extension has clear, detailed, often illustrated information, and excellent videos, including the bulletin Pruning Woody Landscape Plants. The U.S. Forest Service pamphlet How to Prune Trees is an excellent resource.
Let the landscape pruning begin, and let the trees flourish.
Mary Miller is part of the Houlton Canopy Crew, whose members are committed to caring for trees and gardens.