Prune a third of the oldest branches all the way to the ground each.

How to Prune a French Lilac. 1. Plan to prune the French lilac in the spring when it finishes flowering. The buds for the next year form during the summer. Late pruning removes 2.

Cut spent blooms off of the lilac with pruning shears. Even out the length of the branches when you remove the dead.

Apr 02, How to Prune Lilac Bushes. When pruning lilacs, cutting back the tops of overgrown stems is oftentimes not enough. It is generally better to cut the entire stem. Trimming lilacs is best accomplished using clippers. Remove spent blooms all the way to the stems to prevent seeding and encourage more blooms later on. Cut back about a third of the branches. Jul 08, How to Prune Lilac Bushes Regular Maintenance Pruning. The general shrub pruning rule is to cut no more than a third of the stems each year.

2  Rejuvenation Pruning. Older lilacs can have stems as thick as small trees and will flower only on. Jun 02, Yes, you may. Prune lilacs immediately after blooming, so that you don't cut off flower buds for next year. Here is an article about lilacs, including how to prune them, and while it talks primarily about removing the thickest branches, you may also cut back the lilac, as you propose to do.