QUESTION: LILAC HEDGE On my South Minneapolis property separating the alley...

Asked March 10, 2014, 4:07 PM EDT

QUESTION: LILAC HEDGE On my South Minneapolis property separating the alley from my backyard, I have a lilac hedge that must have been there for at least sixty years or more. It is currently about ten to twelve feet tall, and I try to trim it back a foot or so every year to keep it even. It has of course become very woody with more and more dead branches, and it is barely flowering anymore with any springtime purple or white lilacs. I have read that these might be drastically cut back almost to the base, and then allowed to regenerate over the next few years. Is this a viable or recommended procedure? If so, how far down should I cut all of the bushes. To a foot off the ground? Three feet? And if so, when should this be done? March? April? Autumn? And could I just go in with a small chainsaw to level it all out if that is the case? Thank you.

Hennepin County Minnesota

1 Response

This is a very timely question. Lilacs are early bloomers, and the blooms are on old wood - last year's growth. They get pruned after blooming. When a shrub has gotten overgrow, the technique to use is rejuvenation pruning. That is a more vigorous shaping designed to remove old wood and suckers, and restore the shrub to a more balanced shape with younger stronger trunks. It is done over a period of three to four years, as only one-third of woody tissue can be safely removed annually. The following has more information including proper cuts to make, and appropriate tools. Be sure to clean all cutting tools with aclohol between uses on different plants.

Pruning Trees & Shrubs:
http://www.extension.umn.edu/garden/yard-garden/trees-shrubs/pruning-trees-shrubs/