How close can you trim lilac bushes?

When trimming lilac bushes, it's best to prune them back to about one-third of their height, but you can cut them as close as 12 to 18 inches from the ground if necessary, especially for rejuvenation. This encourages healthy growth and blooming in the following season. However, avoid heavy pruning in late summer or fall, as this can remove buds for the next year's flowers. Always ensure to use clean, sharp tools for a clean cut.