Summer Shrub Pruning
Question: My shrubs have become irregular in shape. Is this a good time to prune them? A neighbor said I should wait until fall. Do I need to wait until fall to prune?
Answer: Summer is a perfectly acceptable time to prune most plants. In fact, now is the best time to prune spring flowering shrubs like rhododendron and azalea. Spring flowering shrubs begin forming flower buds for next spring in the late summer and fall. Pruning in the fall would remove many of those buds and reduce next spring’s bloom.
Most plants have produced most of their growth by now. Others will continue to grow for another month or two. Even if additional growth is made this year, pruning will redirect that growth so that you will continue to have a natural shape. One exception would be hedges. Hedges pruned now to a sharp, square shape, may become somewhat rounded before the end of summer.
With the exception of hedges and plants which you want in a formal shape, I recommend pruning shrubs one branch at a time. Pruning plants with power clippers causes them to grow artificially thick. Shapes become artificially rounded or squared like boxes.
If a shrub has only a few branches that are irregular, start with the longest branch and cut it shorter than surrounding branches so that the stub is hidden. Then do the same with the next longest branch and so forth until a more regular shape is obtained. With plants which do not need to be reduced in size, this may only require a dozen or fewer pruning cuts.
Some shrubs become too tall or wide and block access or view. In general, they can be reduced by up to 1/3 in size. If ¼ to 1/3 is not enough to bring them to an acceptable size, then consider removing them and replacing with a smaller shrub which will not grow beyond its bounds.
When I want to reduce plant size I start with the lowest branches and bring them back to a boundary line such as lawn edge. Then I shorten each succeeding layer of branches a little more that the ones below them. This creates a tapered shape which allows plenty of light to reach the lower leaves. When lower leaves are shaded by upper growth, plants begin to shed them because they are not as efficient. This can create a bare look at the base which is less attractive.
Each branch should be shortened a little more than surrounding growth so stubs are hidden inside other growth. Where possible, prune just above a side branch or leaf. This avoids creating bare spots with no green growth. This is especially true for evergreen needle shrubs such as juniper. They do not produce new green growth from brown tissue.
Broadleaf shrubs like spiraea, forsythia and andromeda will regrow from drastic pruning to within a foot of the ground. Then they can be maintained at a smaller size. This process usually takes a full year or longer.