Can you cut down overgrown lilac bushes and have them come back to form flowering neat bushes in the spring?
Certified GKH Gardening Expert
Here is a link to an extension article that will give you a few options on how to rejuvenate your overgrown lilacs. Regardless of your approach, it will probably take a few years to get vigorous attractive shrubs.
For more information on pruning lilacs, visit:
I would suggest you cut them down to no lower than a height of four feet. However, be sure there are new canes coming up as lilacs rejuvenate themselves through new canes. If there is a sufficient number of new canes coming up, cut and remove maybe three of the old canes that appear to be dying.
You can dig out new canes around the outer perimeter and start new bushes with these new canes. The new canes also can be planted to bolster aging lilacs that are the same variety.