Winter is the best time to prune trees. Photo courtesy of University of Maine Cooperative Extension

If the trees in your yard – evergreen or deciduous – need work, there’s no time like the present.

“Now until early spring, before the buds break out, is the best time for pruning,” said Chris Plante, district manager of the Portland branch of Davey Tree.

Because trees are dormant in winter, pruning them now causes less stress to the trees than at other times of the year. In addition, the diseases that might infect spots where an arborist cuts branches are less prevalent in the cooler weather.

Plante warned, however, of a three- or four-week backlog before any in his crew could get out to do the work. Still, the timeframe is a lot better than last year, when the company had a 12-week backlog. It has since hired additional help.

Evergreens show stress in winter, Plante said, because they can’t pull moisture up from the frozen ground. Evergreens store moisture in their needles for the winter. If they don’t get enough moisture stored before the ground freezes, the needles turn brown. If your evergreens are brown on the tree’s interior, it is probably natural dieback and nothing to worry about. But if the exterior needles are brown, that indicates a problem, and your tree may require pruning.

It’s too late for this year, but prevention is the best medicine, Plante said. Next fall, make sure your evergreen trees are properly watered. Browning and die-back are especially common in drought years, and we’ve had a few of those recently, lord knows. Spraying evergreens in the fall with an anti-desiccant, which prevents moisture from evaporating, is a stop-gap measure. It’s not as good as proper watering, but it wouldn’t hurt if you do it in the fall.

Deciduous trees are also best pruned in winter, Plante said. Sections of trees that have been damaged by pests, such as winter moth or browntail moth, may be dead areas that should be cut back. If the damage covers a lot of the tree, the entire tree will have to come down, Branches too close to a house, and endangering it, may also need pruning, Plante said. Sometimes pruning is done merely to improve the shape of a tree, he said.

The most dangerous jobs, he said, are those where trees or limbs have been felled by storms and hit a building. Often, the tree is still attached to the ground, with its top limbs resting on the roof, creating stress in both spots. “That requires a whole different set of skills,” Plante said.

Many books exist on pruning trees and shrubs, and I have read a lot of them. My rule is that if I can’t prune a limb with my feet on solid ground, I won’t do it; I’ll hire an expert. Plante approved. Arborists spend a lot of time high up in trees, using bucket trucks, or climbing the trees while secured with rope. But even if you aren’t leaving the ground, a professional will likely do a better job at shaping the tree, making clean cuts and not leaving stubs.

All arborists must be trained and licensed, with several different levels of licenses. Davey offers some classes in-house; other classes are offered at schools such as Southern Maine Community College. The top accreditation comes from the International Society of Arboriculture, which requires three years of professional experience before someone can even apply.

It’s a pretty emerald color, but the emerald ash borer is bad news for Maine’s trees. Photo courtesy Dr. James E. Zablotny, USDA

What worries Plante most is the emerald ash borer, which has arrived in southern Maine and is slowly spreading. Like state officials, Plante urges people to avoid moving firewood, which can carry the pest from place to place.

A treatment exists for ornamental ash trees, Plante said, an injection (it must be done by a professional) – that will prevent the beetles from killing the trees. It’s not a perfect solution, though, as it lasts only two years before the tree needs a new injection. And unfortunately, such injections aren’t feasible for the wild ash trees that grow in the Maine woods.

Tom Atwell is a freelance writer gardening in Cape Elizabeth. He can be contacted at: tomatwell@me.com.