First things first: if a branch is less than three metres from medium-voltage power lines that cross your property, the law is clear. Only Hydro-Québec personnel or a professional tree trimmer authorized by the utility can prune or fell trees on your land. If there’s no danger from power lines, here is how to prune a tree effectively, in three easy steps.

Dead or broken branches should be removed from a tree as soon as possible. Besides being a hazard for passersby if they fall, these branches also represent a real danger to the tree itself. An untreated break (just like a bad cut) provides an opening for fungus or bacteria that can cause rot and damage the tree. A prompt and proper pruning, on the other hand, is conducive to natural healing of the wound.

Which tools to use

Branches larger than 25 mm (1 in.) in diameter should be cut with a saw. If the branch you need to remove is smaller, use pruning shears with curved blades.

Pruning in three easy steps

Use the following technique for branches thicker than 50 mm (2 in.), so that when the branch falls, bark won’t tear away from the healthy part of the tree:

1. Cut an initial notch on the underside of the branch, about 300 to 600 mm (1 to 2 ft) from the trunk or the main branch (Cut No. 1 in the illustration).

2. Cut the branch off beyond the first notch (Cut No. 2).

3. Saw off the remainder of the branch (the stub) just beyond the branch collar, where the bark wrinkles at the joint with the trunk (Cut No. 3).

A proper cut should be straight and neither too close to, nor too far from, the trunk or main branch. Cutting too close will expand the area of the wound and remove part of the tissue that helps scarring. Cutting too far out will leave the stump vulnerable to parasites, which is the last thing you want!

To avoid the risk of infection, remove damaged bark at the edge of the wound with a sharp tool (e.g., wood chisel or gouge) and smooth the area with sandpaper.  

Greenery near electrical wires

If you have vines, ivy or other climbing plants on the exterior walls of your house, make sure they are trimmed well back of the electrical service mast and the braided wires leading to it. Don’t rely on the rubber insulating sheath around the wires: it could be worn, and if a climbing plant full of sap comes into contact with bare wire, it could become a conductor and cause electrocution. If you have a climbing plant twisted around electrical wires, contact Hydro-Québec.

When—and when not—to prune

Except in the case of trees that produce flowers or edible fruit, pruning can be done at any time of year; threatening branches are a common sight after a harsh winter, for example. If possible, however, you should avoid pruning at the following times:

  • In the depths of winter (January and February);
  • When the sap runs during the spring growth period;
  • In late summer.

Don’t cut into neighbourliness

If you have a tree that is encroaching on a neighbour’s property, good relations are obviously preferable to a conflict. But don’t feel obliged to cut down all your greenery! The mere fact that a tree’s branches are blocking a neighbour’s view or casting too much shade on their property is usually not grounds for them to demand that you prune or cut down that tree.

On the other hand, always be sure to have the consent of your neighbour before working on any branch of a tree located on their property. This is the law, even if one or more branches are overhanging your property and posing a threat.

If your neighbour doesn’t agree, you can obtain a court injunction authorizing you to proceed—as long as you can prove, using photos or an expert report from a horticulturalist, that a nuisance or danger exists. Another condition: your request to a reluctant neighbour must be made formally in writing.

Sources: CMHC, Montreal Botanical Garden