Gardening with Allen: Take more off the top with hedges
By Allen Wilson for The Columbian
Published: September 17, 2019, 6:01am
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My hedge has made a lot of growth this summer. The upper branches have grown a lot more than the lower ones. Should I shorten upper branches more than lower ones to return it to its former shape?
Yes, you can restore your hedge to its normal shape by shortening the upper branches more than lower ones. In fact they should be shortened so that they are shorter than the lower ones. One way to do this is to start pruning about halfway up the hedge. Gradually prune more and more as you go up until the hedge is narrowest at the top. Only enough pruning should be done below the halfway point so that the lowest branches are a little longer than those growing higher up.
This keeps the upper branches from shading the lower ones. When lower branches are shaded, they become less productive, so the hedge plant gradually drops the leaves in the shaded area in favor of the more productive leaves receiving the most light. By keeping a hedge tapered so it is slightly narrower at the top than at the bottom, lower leaf growth stays full and leafy clear to the bottom.
Hedges are generally sheared because we want them to grow thickly and have geometrical shape. However, when we have to restore shape by making deeper cuts, it may be necessary to make individual cuts with loppers on larger branches.
If you have to prune so deeply that you go past the point where the branches are bare of leaves, you may need to compromise and do a gradual reshaping. Broad-leaf plants will normally produce new stem growth even when all leaves are removed. Needle leaf evergreens usually will not produce new green growth if cut back to the point where there are no green leaves.
Rounded shape preferred
Most broad-leaf shrubs like pieris, laurel, photinia, spiraea, cotoneaster, pyracantha, lilac, willow, red twig dogwood, and potentilla can be pruned back almost to the ground to build them back to a healthy tapered shape.
Hedges do not have to be flat on top. I prefer to give them a rounded shape. Of course they can be shaped into many unusual shapes if started when they are small or after severe pruning.
When other shrubs are sheared, they gradually lose their natural shape and develop thick layers of leaves. If you do not want a hedgelike appearance prune them one branch at a time. Make some of the cuts deep inside the shrub to open space between branches.
Early fall is a good time to prune hedges and other shrubs after they have finished their growth. However, flowering shrubs such as azaleas should be pruned shortly after bloom so you do not remove the flower buds which develop in the late summer and fall.
