Gardening with Allen: It’s never too soon to prune most plants




Allen Wilson is a Vancouver gardening specialist. Email Allen Wilson at

I have some overgrown shrubs. Is this a good time to trim them?

For most plants, fall and winter are excellent times to prune. By now, plants have become dormant and pruning will not stimulate new growth. However, spring-flowering shrubs have their flower buds already set. Pruning now will remove many of those buds and reduce next spring’s bloom. Rhododendrons, azaleas, lilacs, forsythia, spirea and heather should be pruned in the summer. It is all right to prune these shrubs now if you do not care if you remove the flower buds.

Avoid using power clippers or shears to prune unless you want a formal shape such as a hedge or upright cone. Shearing causes plants to grow very thick with multiple branching on the outer edges. Inner tissue is shaded and stops producing leaves.

Most plants should be pruned one branch at a time if you want to maintain a natural shape and thickness. Upper branches grow faster than lower ones so they should be shortened more. Otherwise you end up with an “upside down” look with upper branches shading lower ones. Shaded branches begin to lose their leaves.

When shortening a branch, try to prune it a little shorter than surrounding branches. This way the stub will be hidden inside other growth. Prune just above a side branch if possible. This keeps the natural thickness of the plant.

Not all shade trees need to have lower branches pruned up to 6 feet or higher. Lower branches can be beautiful if they are growing in an area where there is no conflict with traffic. Evergreen trees can have branches clear to the ground. If their branches touch the ground, most weeds and grasses will not grow underneath because of lack of light. Fallen needles can be left underneath as mulch.

Young shade trees will develop larger, stronger trunks if lower branches are allowed to grow for the first few years. The leaves on lower branches produce food, which feeds the trunk area where they are growing. Lower branches can be shortened to keep them from growing too large. Once the trunk is strong and well established, lower branches can be removed.

When branches 3 inches or larger in diameter are removed, they should not be cut flush with the trunk or larger branch. A collar of one-fourth to one-half inch will leave vital wound healing tissue.

If you don’t feel competent to prune your own plants, give me a call. I can teach you how to prune in your own yard.