News / Life / Clark County Life

Gardening with Allen: Fall is a good time for pruning

The Columbian

Published: October 8, 2022, 6:05am

Is this a good time to prune my plants? Is there anything I should avoid pruning?

Fall is a great time to prune most plants. They have become dormant and deciduous plants are losing their leaves. This makes it easier to see where to make pruning cuts.

Spring flowering shrubs such as rhododendron and azalea should not be pruned now. They already have their flower buds developed for next spring’s bloom. If pruned now, all or most of those flower buds will be removed, resulting in very little bloom. The best time to prune them is in the summer shortly after they bloom, but before flower buds have developed.

If you would like your shrubs to have a natural shape and thickness instead of looking like balls and boxes, put your power clippers away and make individual pruning cuts, one at a time. When plants are sheared, the tips of many branches are cut. The response from this type of cut is three or more branches growing back where one was cut. After shearing just three times, 25 or more branches grow for each original branch. This is the kind of thickness wanted in a hedge, but not for most shrubs.

To maintain the natural shape of a shrub, upper branches need to shortened more than lower ones. Since lower branches grow more slowly than upper ones, if they are cut the same amount, they soon become shaded. Shaded branches slowly lose their leaves becoming what I refer to as the “chicken leg look.”

I like to prune just above a side branch if possible because you get one branch growing back from each one that is pruned. This keeps the same natural thickness.

If a shrub is too thick or one area is too thick, entire branches can be removed back to their origin. Sometimes it is necessary to go deep and remove branches that have several side branches above them.

A small amount of pruning can help young trees develop. A single leader trunk is usually the safest and most beautiful. If the top of the trunk is damaged, multiple branches will grow upward. All but one should be either shortened or removed so there is only a single leader.

Although most shade trees have lower branches removed up to 6 to 8 feet as the tree grows in height, shortening rather than removing them will help the trunk develop a larger diameter sooner. The food manufactured by these branches is used by the tree for its development right where they are located. Shorten branches to approximately a foot for two or three years before removing them entirely.

Main side branches on trees that have a crotch angle of less than 40 degrees have a very weak attachment and can damage the tree badly when broken in a storm. Narrow crotch angle branches and branches that grow straight up should be removed while they are still small.

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