I have a huge mimosa that was damaged in the ky ice storm last winter. Only a fourth of the tree had foliage this year. Do I begin trimming or wait until next spring to see if there is any regeneration.
In the fall after weather gets cold is a good time. They usually say after the tree goes dormant, but I find that at that point it is a lot harder to tell which is the live part and which is the damaged part. So I do it when it's gotten cold, but before the leaves drop.