I have a 5 ft. Chinese Elm hedge that is too tall and too wide. It’s growing too far into the sidewalk and the neighbour’s driveway. How much can I lower it? How far in can I cut it to make it narrower? Can I cut it into bare wood that has no leaves? Is this a good time to do it? I’m in Toronto and the hedge is in full sun with sandy soil. Thank-you in advance for your help.
Chinese elm (Ulmus parvifolia) is a common urban tree because of its willingness to be planted in a contained space–such as along a sidewalk. They are also fast growing plants often used for privacy hedging. Left to their own devices though, they can quickly grow in to 60-foot trees. Regular pruning is essential to keep the hedge trained to the size that you want it. It would seem that you would like yours quite contained, so that may mean pruning monthly or even weekly during the growing season.
There are two types of pruning: Regeneration, which involves cutting the hedge to almost ground level and Renewal which means cutting out the older stems near the base. The Chinese elm is quite resilient and will make a good recovery from being severely cut back. So you might try cutting it back to about two and a half feet tall. Prune the hedge flat on top, to make frequent pruning easier. Once cut down in height, use hedge trimmers of clippers to trim the sides of the hedge, angling inward toward the top of the hedge. This will allow sunlight to reach the bottom and create a healthier hedge. You can prune to the desired width . More frequent pruning is the best solution for keeping the hedge the size and shape that you require. It would not be wise to cut the hedge to bare wood as the plant would die without leaves, as it would unable to photosynthesize (take in water, air and sunlight). General pruning of the hedge could be done at any time, but if you are going to cut it back hard to renovate it, it would be best done when it is dormant, in late winter or early spring. If it is already leafing, you should leave the regeneration for next year.
If you feel that you cannot spend the time necessary to keep your hedge pruned to fit the space, you might consider removing it and replacing it with a more compact plant or other form of fencing.