We live in Grand Bend, ON. We want to trim these large healthy pyramids cedars because they are obstructing our river views. Can they be trimmed? And if this can be done, how so?
Thank-you for consulting Toronto Master Gardeners with your question about cedar pruning.
At 30 feet, your cedars will pose a few pruning challenges. First and foremost, you will likely need to bring in a professional to prune the trees safely at that height. You can find qualified arborists at https://landscapeontario.com/
Another important issue to consider is that cedars should not be pruned back beyond their green growth. Pruning into the brown “dead zone” will leave exposed brown areas which will never regenerate green new growth, leaving your trees disfigured. When attempting to reduce height on trees that have not been pruned for height regularly, you will need to take care not to remove more than 1/4 of the foliage. Removing more than that will cause the tree to lose significant vigour. The best approach is to remove growth gradually over the course a a few years to reduce height.
Here is some general information on pruning a mature cedar hedge from a previous TMG enquiry:
Good luck with your pruning project!