By PAUL HETZLER

There are many “right” times to prune trees, like when you finally get the time. An old arborist tells me it’s any day the saw’s sharp, meaning he has to earn a living year-round. So far as tree health is concerned, the optimal pruning time is right now, from mid-March until the buds open.

Just as changing a tire using pliers would be miserable, so too is pruning with cheap, all-purpose tools. You’ll never regret investing in a high quality hand pruner, lopper and hand saw. At the very least, borrow a professional-grade hand saw—you’ll be amazed at the difference.

“Proper pruning is full of threes.” And trees, of course. Put on your 3-D glasses and remove any dead, damaged and diseased branches. When it comes to live wood, no more than one-third of the branches should be removed during any pruning cycle, typically three years for shade trees. Younger trees can tolerate heavier pruning, while old ones need a lighter touch.

If you find two crossing/rubbing branches, take the less desirable of the two. When possible, favor wide branch attachments over narrow ones, which are more prone to breakage. Usually, branches are cut at the trunk, but sometimes it looks better when you prune back to a side branch, so long as it’s at least one-third the diameter of the branch you’re taking off.

Another rule is that two-thirds of a tree’s leaf area should be in the lower half of the crown. Lower branches are essential. It seems hard to believe, but on hot summer days the leaves in the upper the upper canopy actually get too hot to photosynthesize. But they shade the lower branches, which carry on essential tree business until things cool down.

Obviously, maples will “bleed” if pruned now. While the loss of sugars is not considered significant, you may want to prune maple (and butternut, hickory) trees in mid- to late July, the second-best time (tree health-wise) to prune trees. Put away the saw, though, during spring leaf-out and again during fall color—pruning in these times can lead to serious long-term problems. For trees, mostly.

“Prune the branch, not the trunk.” This statement, ridiculous on its face, is important. At the base of most branches is a swollen area called a branch collar, which produces fungicides (seriously). The branch collar is part of the trunk and should never be cut. In other words, flush cuts are bad.

In the past, pruning cuts were painted with various compounds, but research has shown that coated wounds decay faster and more extensively than untreated ones. To the best of my knowledge, though, people-cuts can still be treated with Band-Aids. Keep some on hand—good pruning tools are really sharp.

Paul Hetzler is a forester and a horticulture and natural resources educator for Cornell Cooperative Extension of St. Lawrence County.