overgrown cedre hedge

(Question)

White cedre hedge is 8 to 10 ‘ tall and I can no longer trim the hedge properly. At places it is now 6′ across at its top and has suffered major snow damage. I would like to cut the hedge to a 4’ height. Will the hedge survive this type of pruning?

(Answer)

We’ve had a tough couple of winters, and I am almost certain that trouble with cedar (Thuja occidentalis) trees and hedges are close to the top of the list of questions we deal with, here at the website. Wind, dehydration and snow load are often the main culprits.

Your hedge sounds top- heavy, and much of the damage may be a result of being unable to support the snow. Even so, cedar can take pruning, but some observation is required first:

– bent or broken branches?

– split trunks?

– large bare areas along the lower part of the tree?

The first two issues require maintenance with cutting away the damaged areas – this may indeed cause awkward looking pruning, which can be solved with cutting back the hedge, which may be your reasoning for doing so. The third observation will affect the look of your hedge, probably permanently. As cedar grow, the new growth is always at the tips, towards the sunlight. The green leaves eventually die out without sun in the middle of the tree, right to the trunk. All is left is bare, brown branches. Even trimming to that point, the leaves don’t come back.

So, you must ask yourself, if you prune the hedge to about 1.3m or 4 feet, would the look be pleasing to you? The trees will survive, and begin their new growth at top branches, some even to become the new leaders, but would it be what you want? For more information:

https://www.torontomastergardeners.ca/index.php/factsheet/evergreens-suitable-for-hedging-a-toronto-master-gardeners-guide/

It may be best to top them to slow the vertical growth, and continue to shear the new growth, or perhaps remove the hedge altogether and plant a new one. Either way, regular deep watering is needed for moisture-loving cedar, as is regular pruning and shearing in spring and even later in early summer. Fertilizing with evergreen food keeps them green.