Trimming large, mature white cedars


I received a quote from an arborist in the summer to trim large white cedar hedges. They are about 40 years old. Last few years we have been unable to prune them professionally, so they are overgrown. The neighbour on the opposite side also cut them on her side to the trunk! Bald! The health of the trees on my side look ok. After receiving a quote and confirming trimming and taking down two feet off the top back in the summer, the work now is being planned for in early November. We couldn’t have it done earlier as they were busy.

My question is, given the mature trees, is November too late in the year to prune and reduce it’s height? We live in the Greater Toronto Area. I am concerned it may be too late this season to cut them, but I do want them to thrive next spring and get them in better shape. Thanks.


Thank you for sending your question to the Toronto Master Gardeners.

Cedars are very versatile and can be trimmed at different times of the year. According to Mark Cullen,  you can trim a cedar hedge most anytime of year without hurting it. “You just cannot hurt it by pruning it at the ‘wrong time’ even in mid winter. However, there are better times of the season than others for pruning/trimming”. Cullen prefers September, so that you are shaping your hedge and still giving it time to fill in before freezing temperatures set in. That said, since pruning stimulates new growth, a good time to prune is also late spring or early summer. To get the optimal benefits for your hedge, and to avoid possibly damaging any new growth from frost or snow, you might want to reschedule your appointment.

For more information on proper pruning techniques, please see the link below.

Good luck with your hedge!…ncourage-opacity/