Wednesday, December 8, 2021
Dec. 8, 2021

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Gardening with Allen: How to prune your trees


Some of my trees need to be pruned. Can I do some of the pruning myself or should I just hire an arborist?

You could do some of the pruning yourself if the trees are not too large. Most needle-leaf evergreen trees do not need much pruning unless they suffer damage. Occasionally, the top becomes damaged and instead of a single upward growing leader, two or more branches start to grow upward. Simply leave the strongest one and shorten or remove the others. Sometimes one or more side branches will grow longer so the tree is not symmetrical. Simply shorten the long branches. Most needle evergreens look best if all the branches are allowed to grow down to the ground. Pine and fir trees sometimes have some of the lower branches removed.

Broad-leaf trees, whether deciduous or evergreen, usually have lower branches removed up to 6 to 8 feet as they grow in height. It is best to shorten rather than remove lower branches until trees reach a height of at least 10 feet. These 6- to 12-inch shortened branches feed the trunk where they are located and cause it to grow in diameter faster than if they are removed entirely.

If branches become broken or damaged, they should be pruned just above a smaller side branch or removed entirely. When removing branches, look for a raised area on the branch near the trunk which resembles a collar. This collar contains wound healing tissue which will recover the cut more quickly if left unpruned. Use a three-cut method for large branch removal. The first cut should be made from underneath a few inches above the final cut. The second cut should be made from the top a few inches beyond the first cut. If the weight of the branch causes it to snap while you are making the second cut, it will not tear bark any further than the undercut. Then the stub can be removed in the third cut.

Trees should never be shortened at an arbitrary height by shortening all branches above that height. Unless shortened just above a smaller side branch, they will regrow three or more weak branches that will be subject to wind damage.

Most shade trees do best with a single dominant trunk. When side branches grow rapidly and become almost as large as the main trunk, they should be shortened or removed. If the tip of the original main leader or trunk becomes damaged, leave one upright growing branch to become the new leader and shorten or remove all others which are trying to become leaders.

No more than one-fourth to one-third of growth should be removed with any single pruning. Any pruning that requires a ladder should be reserved for a licensed, certified arborist, especially if utility lines are nearby.

Allen Wilson is a Vancouver gardening specialist.