Taming a rogue lilac bush

We have a lilac bush in our side yard. Surprisingly, we actually really like where it is (unlike a lot of other plants that we inherited), and when we moved in over 2 years ago, it was little. But after years of no pruning (probably never been pruned) and lots of rain this summer, it got a little too big for its britches (on the right.)


We walk right in between these 2 bushes to get to the backyard, so they both need to be maintained and shaped so as not to crowd that area. Lilacs can be much bigger and still healthy, we just want to keep ours smaller. It also just recently got big enough that it started killing the grass underneath. Bad lilac!!


Ours currently has a fungus, but we’re still working on that, too…


I had never pruned a lilac before, or many bushes at all really, so I did some research and here’s what I learned.

  1. First, I found out that because lilacs set new buds almost immediately, you want to prune as soon as the bush is done flowering (usually in the summer). Fall is not the best time to prune. Pruning encourages growth, and you don’t want the plant to be putting effort towards new growth just before winter. Ours had also set new buds already, but we were pretty desperate, so I decided to go ahead and do just a little. I’ve also heard lilacs are hardy. Let’s hope so.
  2. When pruning, you want to remove new shoots that aren’t growing where you want them, dead wood, and branches over 2″ in diameter, as the older wood is more prone to disease (like borers). Same goes for any branches that are rubbing against another. This may create a “wound” which can be an entry point for disease.
  3. Bushes should have an “open center.” This provides good air flow and allows more sunlight to reach the center, helping prevent diseases like powdery mildew (likely what our lilac has).


Clearly our lilac does not have an open center.


Every site I looked at recommended a 3 year plan for making over your lilac. Each year, remove one-third of the large, stocky branches (anything bigger than 2″ in diameter) by cutting them all the way back to the ground. This way you will still have some blooms each year. You can do all of it at once, but for several years might have no blooms on your very sad looking bush. (If you go this route, make sure you still retain some leaves so the bush can create food!)

I have to admit, I was a little afraid to get started. I know my way around a crepe myrtle, but my pruning methods are very different for those since I want them to be more tree-like. So I started with the easy stuff. I removed dead branches first. Then I looked for crossing or woody looking branches, like these.


After analyzing both branches, I decided the bottom one needed to go, so I cut it off where it met the next branch.


After completing that, I stepped back to look at the shape of the bush from every angle and chose a few branches that were creating a shape I didn’t like. I cut those off at the base. Then I stepped back again and picked out areas that still looked a little too thick. From these areas, I pruned inward growing branches back to the branch beneath that was growing in the direction I wanted (like the diagram above demonstrates). And my lilac went from this overgrown mess of branches…


To this.


It’s a little closer to the shape in the diagram, huh? It’s still not perfect, but c’mon, this is the 3 year plan. I probably didn’t actually prune off one-third of the thicker branches because I was worried it would look too bare!! Hopefully with the increased sunlight the base will be getting, there will be more new shoots next year so I can prune off a few bigger branches without it looking too sparse.

I also didn’t do much deadheading or pruning at the tips since the new buds had already set. I didn’t want to cut them all off! I’ll wait to do that part until right after the bush is done blooming next year.


Now that I’ve educated myself on how to prune a lilac and taken a first swing…er, snip at things, I think each year will be progressively easier and faster. Realistically, I don’t think it would take more than 10 or 15 minutes once per year to maintain it (since mine is small and I want it to stay that way.)

Here’s one last before and after. Before looking scraggly and wild.


And after…maybe looking a little sheepish next to the very full crepe myrtle.


Pruning doesn’t yield a perfect result immediately, but it always surprises me how drastically improved a plant is after the second year of pruning! Even after this one round of pruning, I’m much happier with our lilac. Now we just need to work on this powdery mildew situation…

I have to remind myself, too, that even if I don’t know exactly how to prune each plant, doing something is better than nothing and can go a long way to making your yard look cared for and well maintained. (Unless you’re topping a crepe myrtle. Then, just don’t. Your yard will look like a tornado hit it and wiped out your shrubbery. Say no to crepe murder!)

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