Can you trim a lilac tree in August?

Yes, you can trim a lilac tree in August, but it's not the ideal time. Lilacs typically bloom in spring, and the best time to prune them is right after they finish flowering to promote healthy growth and blooms for the next season. If you must prune in August, focus on removing any dead or diseased branches rather than shaping the tree, as significant pruning can reduce next year's blooms.