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How to Prune Lilacs

By Mark Viette ; Updated September 21, 2017

Lilacs can be pruned with a standard set of pruning sheers, so long as you follow the proper directions. Prune lilacs with help from a gardening specialist in this free video clip.


I'm Mark Viette, and I'm going to talk about how to prune shrub lilacs. Well really, I pronounce lilacs; most of you are going to say lilacs, but here is an overgrown sixteen foot tall lilac that probably was planted twenty four years ago. As you can see, these are shrub lilacs. In other words, they produce a lot of stems coming up out of the ground. This is not a tree lilac. You prune that differently. I have an option. I can come in, spend eight hours thinning this out, taking the oldest branches and some of the youngest branches. But, that's going to really waste my time. What you might want to do is what I did two years ago. I came in and completely cut a lilac as big as this one right to the ground, two inches from the ground. Just came in, cut it and look at it two years later, beautiful blooms that you can see not top of the shrub itself so you can never see him; nice long stems that you can cut as a cut flower. Once you get your lilac to this point, you can go ahead and thin it out which I'll show you right now. The first thing you want to do is look at your lilac shrub. And you'll notice on some of the old growth that died back that's occurring on this branch, it's occurring on others; as I look at this overall plant, I see about twenty shoots total. I'm going to remove at least three. Remember, one to two out of every ten should be removed. So, you just find what you want to do, look at it, walk around the plant, make sure it's the right ones 'cause once you cut it, you can't redo it. And I'm, just going to come in here and as I look, this is the one, one of the ones, I want to remove it just as close as possible; always wear protective eye wear and gloves, just like this and so there's one branch. And my goal is to maintain new, young branches like this and like this. So, I want to remove some of the older ones in this case 'cause there's not a lot of young. Now, if there were twenty or thirty young branches, I would remove about ten to twenty percent of those too. So, when you're done, you're going to see something that really looks great. So, just go in and I'm going to remove about two or three more. I get a little prune happy. In fact, my friends don't even let me come into their homes when I have my shears. I took a few more out that I wanted and you might say, "Wow, this is drastic." But, I will tell you, your plants will thank you in the future. This will help rejuvenate the lilac, it'll send out all these new growths. So, it looks like I've done damage to it, but in fact I've helped it. Now, the ideal time to prune lilacs is before they bloom or after they bloom. Some people will wait 'till after they bloom so they can still enjoy a few flowers. I prefer to prune them back when there's still dormant, right before they begin to grow. I'm Mark Viette, and this is how best you can prune a shrub lilac.


About the Author

Mark Viette received his Bachelor of Science degree in horticulture from Virginia Tech in 1980.