Pruning is one of the most important things you can do for the health and appearance of your trees. But done incorrectly, it can cause lasting damage, invite disease, and even kill a tree. Here are five common trimming mistakes we see regularly on properties across the West Island of Montreal — and how to avoid them.
Mistake 1: Topping the Tree
Topping — cutting the main leader or large branches back to stubs — is the single most harmful pruning practice. It destroys the tree's natural form, triggers a flush of weak, fast-growing water sprouts, and creates large wounds that are slow to heal. We frequently see topped maples and lindens in Pointe-Claire and Dorval. A properly trained arborist will use crown reduction cuts instead, which maintain the tree's structure while reducing height.
Mistake 2: Cutting the Branch Collar
Every branch has a slightly swollen area where it meets the trunk called the branch collar. This collar contains specialized cells that help the tree compartmentalize and heal the wound. Cutting flush with the trunk removes the collar and leaves a large wound that is vulnerable to decay. Always cut just outside the branch collar at a slight angle.
Mistake 3: Pruning at the Wrong Time
Timing matters. Pruning oaks during the growing season exposes them to oak wilt. Pruning maples in late winter causes heavy sap bleeding (though this is mostly cosmetic). Elms should never be pruned between April and October due to Dutch elm disease. In Beaconsfield and Kirkland, where these species are abundant, incorrect timing can have neighbourhood-wide consequences if disease spreads.
Mistake 4: Removing Too Much at Once
Never remove more than 25% of a tree's canopy in a single season. Over-pruning shocks the tree, reduces its ability to photosynthesize, and triggers stress responses. This is a common mistake when homeowners in Hudson and Saint-Lazare try to "open up" a tree for more sunlight. Gradual thinning over two or three seasons is far healthier.
Mistake 5: Using Dull or Dirty Tools
Dull blades tear bark and create ragged wounds that heal slowly. Dirty tools can transfer fungal spores and bacteria from one tree to the next. Always use sharp, clean pruning tools and disinfect them with rubbing alcohol between trees. For branches over 5 cm in diameter, use a proper three-cut technique to prevent bark tearing.
Get It Done Right the First Time
Improper pruning damage cannot be undone — the tree has to live with the consequences for years. Service d'Arbres Brandse employs certified arborists who follow ISA (International Society of Arboriculture) pruning standards. Whether you need a single tree trimmed or an entire property maintained, call us at (438) 365-5410 for professional pruning across the West Island.