5 Tree Pruning Mistakes to Avoid

A lot of the tree damage we see in Orange County yards doesn't come from storms or pests. It comes from bad pruning. A tree can take years to show the harm from a bad cut, and by then the fix is expensive or impossible. Here are the five mistakes we run into most, why they hurt, and what ANSI A300 and ISA best practice say to do instead.

Topping means cutting the main branches back to stubs to make a tree shorter. It goes by other names too: hat-racking, heading back, rounding over. ISA calls it one of the most harmful pruning practices there is, and ANSI A300 does not accept it as a pruning method.

Why it hurts: topping can strip off most of a tree's leaves at once, so the tree starves. It answers with a flush of fast sprouts that grow from the outer layers of wood and are only weakly attached. A few years later those sprouts are heavy, crowded and prone to snapping, so the tree is often more dangerous than before. The big stub wounds also invite decay and sunburned bark.

Do this instead: crown reduction. An arborist shortens branches back to side branches at least one-third the size of the cut stem, keeping the tree's natural shape. If a tree is simply too big for its spot, replacing it with the right species is often smarter than topping it over and over.

It looks tidy to cut a branch perfectly flat against the trunk, but that cut goes through the branch collar, the swollen ring at the base of the branch that holds the tree's natural defense against decay. Flush cuts leave bigger wounds, and the bark above and below them often dies back.

Do this instead: cut just outside the collar, leaving it intact. Our guide to proper pruning cuts shows exactly where.

The opposite mistake is cutting a branch a few inches or a foot out from the trunk. New wood can only close over a wound at the collar, so a stub can't be sealed off. It dies, rots and gives fungi a path into the trunk. Stubs also sprout clusters of weak shoots.

Do this instead: on large limbs, use the three-cut method. An undercut and a top cut take the weight off, and a final clean cut removes the stub just outside the collar. That keeps the bark from tearing too.

Stripping a palm down to a few upright fronds, sometimes called a hurricane cut or a pineapple cut, is common in Southern California. It doesn't make palms safer. UC Cooperative Extension advises removing only dead fronds or, at most, fronds down to an imaginary horizontal line from 9 to 3 o'clock. University of Florida research after hurricanes found over-pruned palms were damaged more often in storms, not less. Over-trimming also weakens the palm, can slow growth and can thin the trunk just below the crown.

Do this instead: keep the green fronds above the 9-to-3 line, remove dead fronds and seed stalks, and skin the trunk lightly without cutting into live tissue. More in our palm tree care tips.

Spikes (also called gaffs or spurs) punch holes through the bark into the living tissue with every step. On a tree that's being removed, that doesn't matter. On a tree that's staying, those wounds can let in decay and disease. ANSI A300 says climbing spurs shouldn't be used to prune trees except in rare cases, such as an emergency rescue. On palms, spike wounds never close.

Do this instead: ask your tree company how they'll climb. At Peterson's, we climb with ropes and harness on every tree we're keeping. Spikes are used only on removals.

Over-thinning or "lion's tailing." Stripping out all the inner branches and leaving a puff of leaves at the ends pushes weight to the branch tips, causes sunburned bark and leads to breakage. As a rule, ISA advises taking no more than about a quarter of the live crown at once, and less on mature trees.

Dirty tools. Saws can carry Fusarium dieback (spread by invasive shot hole borers) and Fusarium wilt of Canary Island date palms from tree to tree. Our crews disinfect tools between trees, as UC IPM recommends.

A well-pruned tree looks like itself, just cleaner. You shouldn't see stubs, flat scars flush with the trunk, piles of sprouts at the tips of chopped limbs, or a palm reduced to a feather duster. If your trees show any of these signs from past work, an arborist can usually correct a lot of it over a few careful prunings.

Have one of our ISA Certified Arborists take a look. We never top trees, never spike trees that are staying, and disinfect our tools between trees. Learn more about our tree trimming & pruning service.