How to Prune a Lilac (and a book recommendation)


I’d never had a lilac of my own until we moved to Maplehurst in Pennsylvania. They don’t grow in the deep south where I grew up.

I didn’t even recognize the lilac for what it was–I’m embarrassed to admit this–for several years. The reason is that our old lilac shrub hardly bloomed at all, and the blooms it did have were high and hidden.

My lilac was in desperate need of rejuvenation through a good and thorough pruning.

I realized this only after bringing home a wonderful  book: Lee Reich’s The Pruning Book.

I bought that book because I needed to learn how to prune our fruit trees, but the book rescued my lilac.

Two things to consider:

  1. Some old lilacs have been pruned into beautiful tree shapes. DO NOT cut back those thick, beautiful trunks. Instead, rejuvenate in a way that adds to their beauty: cutting out dead or diseased wood, cutting back any suckers to the ground, trimming back any over-long, drooping limbs, cutting out some of the thin, wispy growth in order to introduce more air and light into the center of the lilac.
  2. If your old lilac is a twiggy, shrubby mess like mine was you can drastically cut it back (an easy approach but the lilac won’t look good again for a few years) or gradually prune (a little more time consuming but maintains the appeal of the shrub from year to year).

I chose to gradually rejuvenate my lilac, but even the very next spring I had far more beautiful flowers. Here is what I did:

  1. First, I removed big, old stems that were pointing in directions I didn’t like. I cut them back right at the ground.
  2. Second, I cut out some old stems from the crowded middle of the shrub, again, cutting back down to the ground.
  3. Then, I thinned out some of the younger stems so the shrub wasn’t too crowded overall.
  4. Finally, I cut back some stems that were too long and drooping. I didn’t cut them to the ground, just trimmed them back a bit.

For on-going maintenance, the best time to prune a lilac is just after the blooms fade.



Posted on

April 16, 2020

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