Gardening with Allen: Timing key when pruning shrubs
By Allen Wilson
Published: April 9, 2022, 6:02am
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I didn’t get around to trimming my overgrown shrubs last fall. Should I prune them now or should I wait until later? I plan to use my new power clippers.
The normal growth cycle for spring flowering shrubs and trees is to develop flower buds in late summer and early fall. Plants which bloom in the summer, like roses and hydrangeas, develop their flower buds in the spring after new growth. If you prune spring flowering shrubs now you will trim off some or all the flowers. So wait until after bloom to prune them. Needle evergreens and other shrubs which do not develop ornamental flowers can be pruned at any time.
Power clippers are not the best tool to use in pruning shrubs. It is better to cut branches one at a time with hand pruners, loppers or a pruning saw, depending upon the size of the branch.
Branches should be cut inside or below the surface where other smaller branches and leaves hide the stubs. Wherever possible, branches should be cut just above a side branch. If there are no side branches, cut just above a bud. If branches are too thick, some can be removed entirely back to their origin.
Lower branches should be shortened less than upper branches to keep the natural, tapered shape of the shrub. Upper branches also grow faster than lower ones. In some cases no pruning is needed on lower branches. By keeping lower branches longer than upper ones, light is able to reach the lower branches. When lower branches are shaded, they lose their leaves, making plants bare at the base.
One successful pruning technique is to step back and look at the shrub, visualizing what you would like it to look like after pruning. Select an individual branch which is too long and prune it back below the surface of adjoining branches. Then select the next branch which is too long and prune it back. Continue pruning one branch at a time until you reach your visualized size and shape.
Shrubs which have been sheared with power trimmers or hedge shears have had the outer tips of branches cut repeatedly. Each time branch tips are cut, they produce 3 to 7 branches where there was one before. After being sheared two or three times, there are 10 to 20 times as many branches, making the shrub artificially thick.
The best way to correct this artificial thickness is to remove up to a third of the branches 2 or 3 layers deep inside the shrub. It may need to be pruned 2 or 3 times to restore a shrub to its natural thickness.
Sometimes shrubs have been planted too close together and the best solution is to remove some of them so they are not so crowded. When it becomes clear that a shrub just grows naturally to a size larger than its allotted space, it may need to be replaced with a smaller plant. When choosing new shrubs, check to see if the mature size is right for the space where you plan to place them.
