Can I Prune a Lilac in August?


Question: Is August too late to prune our French lilac?

Allie Dipietro

Answer: It all depends on what you want to prune and why.

If you simply want to remove the seed capsules from a common or French lilac (Syringa vulgaris), go ahead … but cut only the leafless stem at the tip of the branch that carries the capsules, not the secondary branches just below, the ones with green leaves. It’s from those branches that next year’s flowers will appear, as, by August, they already carry the buds of the blooms to come. If you cut back too far, removing foliage and not just bare stem and seed capsules, you’ll reduce next year’s blooms.

In passing, deadheading lilacs, that is, removing the faded flowers and the seed capsules that follow, is a popular but essentially useless task. Read Garden Myth: Deadheading Lilacs Improves Bloom to understand why. Do it only if those seed capsules really bother you!

If you want to prune your lilac to reshape it or to reduce its height, you could do it now, but it would be better to wait until spring. You see, if you prune in August, the lilac may produce new shoots that won’t have the time to harden off properly (prepare for winter) and they could be damaged by winter cold, obliging you to prune again in the spring.

If, however, you’re just considering removing a branch that is bothering you for any reason—it rubs against the house, hangs over a path, making foot traffic difficult, is dead, damaged or broken—, etc., by all means prune it now. You can eliminate wayward and unwanted branches at any season.

You can remove suckers at any season. Photo:

Also, if you want to eliminate the suckers that grow at the foot of the shrub—and they can be very numerous—, go for it! Again, you can remove them in any season. Cut them as close to the ground as possible, even below ground level if you can, as this helps eliminate regrowth. Or, dig them out with a shovel.

Garden writer and blogger, author of 65 gardening books, lecturer and communicator, the Laidback Gardener, Larry Hodgson, passed away in October 2022. Known for his great generosity, his thoroughness and his sense of humor, he reached several generations of amateur and professional gardeners over his 40-year career. Thanks to his son, Mathieu Hodgson, and a team of contributors, will continue its mission of demystifying gardening and making it more accessible to all.

3 comments on “Can I Prune a Lilac in August?

  1. First off I would like to say terrific blog! I had a quick question which I’d like to ask if you don’t mind.
    I was curious to know how you center yourself and clear your mind prior
    to writing. I’ve had a hard time clearing my mind in getting my thoughts out.
    I truly do take pleasure in writing however it
    just seems like the first 10 to 15 minutes are generally lost just trying to figure out how to begin. Any
    recommendations or tips? Thank you!

    • Hi!

      Tough question! I really don’t know what I do. I think it helps that I’ve been writing pretty much daily for over 30 years. Also, I’m an early morning person. I get right up and start writing, only breakfasting, showering and shaving when I feel I have accomplished something. Maybe an early rise makes for a clear mind?

      One thought: I do sometimes pick my subject the day before, then occasionally think of it briefly during the day. I suspect my mind works on the subject as I sleep, for when I get up, I’m raring to go!

  2. For the old cultivars, or the straight species, some of the best suckers need to stay to replace aging stems. A long time ago, they used to be pruned with the ‘alternating canes’ technique. I know that no one does this anymore, but it would be so much better for such plants as abelia, forsythia and, of course, hydrangeas. New canes produce only foliage in their first year, and then branch and bloom in their second year. They can bloom for a few years afterward, but should be pruned out before they get old. For lilac, that can be a few years. For hydrangeas and forsythia, it might be only three years, or even two years for a vigorous plant. Abelia is more variable. Stems bloom less and become more gnarly as they age.
    I prefer to prune all such plants while bare in winter. However, for many, it is actually best to let them bloom at their best, and then prune them after the foliage has hardened off.

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