My hedge is starting to lose its leaves on the lower branches. Is there something I can do to restore full lower leaf growth?
Yes, you can gradually restore full leaf growth in the lower part of your hedge. It may take a year or two for this to happen. The key is to shorten the upper branches so they are shorter than the lower ones. One way to do this is to start pruning about half way up the hedge. Gradually prune more and more as you go up until the hedge is narrowest at the top. Very little pruning is done below the half way point.
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 grows 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 on larger branches.
If you have to prune so deeply that you go past the point where there are still 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.
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 on top. 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 hedge-like appearance prune them one branch at a time. Make some of the cuts deep inside the shrub to open space between branches.
Whenever you prune, step back periodically to look at the overall shape of the plant.
Late summer is a good time to prune hedges and other shrubs after they have made most of their growth. However, flowering shrubs should be pruned shortly after bloom so you do not remove the flower buds which develop in the late summer and fall.