Unlocking the Secret to Stunning Lilacs: The Ultimate Guide to Pruning!

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How to Prune Lilacs correctly addresses the different reasons to prune.

Today we are all about How to Prune Lilacs correctly. Is your large lilac not blooming? Or has it gotten too tall to enjoy the blooms at nose level? Have you moved into a new home and you inherited some vintage lilacs?

I have heard many complain that their large lilac is not blooming and there can be many reasons why. But one reason can be that your lilac has not been pruned well or correctly.

So let’s see the different ways to prune your Lilac which is determined by why you are pruning.

heirloom lavender lilac bush in full bloom, Flower Patch Farmhouse

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First, we will start with the basics.

General Maintenance Pruning

When to Prune Lilacs

Lilacs should be pruned right after they finish blooming, which is usually in late spring or early summer. This timing ensures that you won’t cut off any of next year’s flower buds.

If you wait too long to prune, you risk removing the buds and potentially missing out on next year’s blooms.

How to Prune Lilacs

Start by removing any dead or damaged wood. Then, remove most of the suckers that have grown around the base of the plant.

These are shoots that grow up from the roots. Leave a few to replace old or dying limbs that may need cutting to the ground.

Prune out old canes or branches larger than 2 inches in diameter.

Next, remove any branches that are rubbing against each other or growing inward toward the center of the plant. This will open up the plant and allow for better air circulation, which can help prevent diseases.

Finally, shape the plant by selectively removing some of the branches. This will promote new growth and help the plant maintain its shape.

Other Reasons to Prune

the Lilac has been neglected for years

Common Lilacs can last for decades but they bloom best on wood that is under 5 to 6 years old. They will bloom less and less on wood that is older. Plus the blooms are usually too high to enjoy once that old.

For older lilacs that have not enjoyed good annual maintenance a more severe renovation prune is in order.

A good time to do this is in late winter before new growth begins when the lilac is dormant.

You can prune the entire plant back 6 to 8 inches from the ground. This is a very dramatic method and you won’t most likely not see blooms for 2 years but it works.

Note: Check to see if your lilac has been grafted. Check the main trunk of the Lilac and see if there is a bump and difference in the bark. That would be the graft union.

Grafting is where you join a scion of one cultivar to the rootstock of another. If you discover it is a grafted Lilac be sure to remove all suckers from around the base.

Never cut the lilac itself below the graft joint. The shoots or suckers coming up around the base of grafted Lilacs will not be the same bloom type.

Less intense renovation prune

You can also do a renovation prune over a 3-year period. When pruning this way cut out any dead or weak canes, then cut out 2/3rds of the suckers or shoots coming up at the base, leaving 1/3 for future blooming stems. 

How to Propagate Lilacs from Suckers, easy enough if you have a sharp shovel and a bit of muscle.

You can actually dig the suckers up and pot them to make more lilacs if you wish, they actually mature faster than taking cuttings and rooting them. 

Cut back 1/3 of the older lilac canes or branches. The following year cut out the next 1/3 of the oldest branches then the final year cut back the last of the oldest branches.

Doing this in 1/3’s will let you have blooms and still cut back the old worn-out branches fully renovating the lilac.

Some say to have only about 10 canes per bush for best health and others say 2 or 3. The lilacs I have cared for have between 5 and 10 canes and bloom beautifully.

Deadheading Lilacs

Cutting Lilac blooms to bring into the house is a great way to keep your plant healthy. Make the cut at the base of the flowers. This is similar to deadheading but you are cutting off the flowers before they are dead.

The beauty of cutting the flowers is you keep spent blooms from sucking energy from the rest of the lilac. And you get to enjoy their sweet perfume in your home.

Deadheading should be done as soon as possible after the flowers fade if you haven’t already cut them to bring into the house.

The old flower cluster should be cut off at its base, just above the two new shoots that angle out from the stem that ended with the old flower.

New shoots will grow over the summer, set flower buds, and bloom the following spring.

Just after they bloom is also when you cut out unproductive, misshapen, and obviously diseased stems to the ground. Twiggy growth should also be removed.

Thin and remove some canes to give proper spacing for healthy airflow, stimulating robust growth.

Lilacs of white pines, FlowerPatchFarmhouse.com

Cut out suckers straying too far from the plant, cut them to ground level. I have read that the suckers or shoots that maintain a pencil thickness all the way to the tip are the most productive but I haven’t tested that myself. Keep a good few inches between suckers or shoots.

Tipping

Tipping is when you cut back to a pair of side shoots instead of at the base of the spent flowers.

You will need to do this if you get a stem that shoots higher than the rest making for an uneven plant. The benefit of tipping is not only a well-shaped lilac but the side shoots will put out new growth and flower buds for the following year.

I don’t give a particular month or date as the bloom time of your Lilac can be quite different than mine. Here we typically don’t see lilacs blooming until well into May while just 10 minutes down the road from me they bloomed in early April.

Thus the annual pruning time frame is different for each location.

The dwarf lilacs don’t need much pruning. Just deadhead each year to keep neat and tidy. Miss Kim and Bloomerang Dwarf Lilac (reblooming)

FAQs Pruning Lilacs

It’s not recommended to prune lilacs in the fall or winter, as this can remove Spring flower buds.

Light pruning should be done every year once the blooms fade. This can be a mere deadheading or a light maintenance prune.

Yes, you can prune lilacs into a tree shape by selectively removing some of the lower branches and shaping the remaining branches into a tree-like structure.

If your lilacs have not bloomed, it’s possible that they are not getting enough sunlight or other factors. Pruning may not solve this issue, and you may need to address the underlying problem before you can expect to see blooms. See this post for more info.

I hope you found this helpful.

Happy Gardening!

For some wonderful information on how to keep your cut lilacs fresh longer take a peak and Danielle’s video.

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12 Comments

  1. We had a huge lilac beside our house that was on a slope. I planted it as a tiny stick by the downspout from the roof on the second floor. It flourished there. It got as tall as the second story, bloomed furiously and was huge in width and I never trimmed it. My husband decided the leaves were interferring the eavestrough and took the chainsaw to it and cut it back to below the roofline. It bloomed even more and was a magnet for butterflies. It was a kind of lilac that was meant to plant in windrows to slow the wind down on farm land. I now have a lilac that is 7 years old and has been babied and barely blooms. I am thinking of turning my husband and the chainsaw loose on it!

  2. Roxanne Shy says:

    Hi I purchased a moderate sized lilac from big box store this June. Was the blooming time past. It’s a healthy plant. Thanks also I was watering too much and I will correct that. I appreciate your time

  3. Thank you. Everything 10 minutes down the highway from me is a month to 2 months ahead of me in blooming. It is because we live on a mountain and the elevation changes swiftly thus the temperatures in general. From my research on the different varieties, these lilacs in this neighborhood are most likely Syringa hyacinthflora.

  4. Sunflower says:

    The early blooming lilacs down the road might be Syringa hyacinthflora (search for cultivars Sister Justina, Mount Baker) or Syringa oblata. They bloom before Syringa vulgaris.

  5. I will be sure to do that next Summer as it is too late now. A shoot from the ground is a sucker, just two different terms for the same thing.

  6. JustJessee says:

    For those of us with two black thumbs, it would help if there were PICTURES of what to look for along with the text. Not everyone knows a “shoot” from a “sucker” (Me. Me is everyone.) What’s a “dead head” exactly? Where you do you stop pruning on a ‘dead head’….more images please.

  7. Yes, prune them now. It happens that way here at time too when we get a late hard frost, we either get no flowers or very few. This was a good year for them here, we had a mild spring with no late hard freezes. Sorry yours are not performing as you wished but they are rather slow growers in general so it just may be a case of patience for them to get as large as you want.
    I wish you better success with your lilacs. I am glad you enjoyed some of my painting lessons too. I have more coming but right now the garden takes all of my time.

  8. This is great info Pamela, thank you very much! I have 17 French White Lilac Bushes planted across the front of my property – sandy soil – full sun – each bush was encased in a soil pod when planted. I had a green house do this professionally b/c I don’t have a green thumb, so paid quite a bit, and it’s so frustrating. They haven’t grown very tall (as promised), and do not flower much (any year). Many flowers budded, but they didn’t bloom … we had a terrible cold spring here in the midwest, so all the to-be flowers simply turned black … should I prune these off now? Basically they’ve never flowered like a lilac should, and they are growing slow. Thanks so much! (I also have done some of your art tutorials:).

  9. You can still prune now and choose which prune to do. I will try to do an ebook or something similar for some of the posts but I can’t make the entire thing printable. Sorry.

  10. My lilacs have already bloomed (sparsely) and I have never known to prune them. Is it too late to prune now, or do I have to wait until next year?
    Also, could you make your posts printable?

  11. Thanks for the advice on the Lilacs

  12. Thank you Pamela!

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