Tips for pruning lilacs

Tips for pruning lilacs

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A few years ago, when I went to grab the hose, I noticed a ton of branches had been torn off my lilac bush. I accused my poor husband of getting overzealous with the pruners. However, I soon discovered that the hack job was the work of a mother squirrel that was meticulously building her nest. She’d rip off a branch or two and then run to my chimney (that’s a whole other story). I was worried about the lilac coming back the following spring, but it has been flourishing. Lilac is among my favourite spring scents—when I work outside on my deck, I take deep breaths when they’re in bloom, as they sway in the breeze. When those fragrant blooms fade, it’s a good time for pruning lilacs. So I thought I’d share a few tips!

The perfect time to prune a lilac bush is after the flowers have bloomed and faded. Spring-blooming shrubs should be pruned right after they have bloomed. If you save the task for later in the season, you risk pruning off next year’s blooms (because next year’s flower buds form on the current year’s wood)—a mistake I made in the past with an unruly forsythia!

Tips for pruning lilacs

There are three maintenance tasks I need to cross off my lilac to-do list in the spring. I need to trim the dead blooms off, prune the shrubs, and cut out suckers that have popped up underneath. Most of the stems I’m dealing with are thin enough that I can use my hand pruners, but if stems are thicker, you may want to use a pair of bypass loppers. Make sure the blades are clean before you cut. And while the plant is blooming, use the same sharp pruners to snip bouquets. You don’t want to tear or snap off blooms, as this could harm the lilac bush.
Be sure to use sharp hand pruners to trim a lilac bouquet.

Be sure to use sharp hand pruners to trim a lilac bouquet.

Trimming off lilac flowers

Removing the dead flowers from your lilac bush will encourage more blooms the following year. The important thing when trimming off your flowers is that you simply cut off the spent flowers—don’t worry about any surrounding stems. If you can see next year’s blooms forming (two new shoots coming from the stem), simply focus on the spent bloom’s stem. You don’t want to cut off next year’s flowers!

deadheading lilacs

To deadhead lilacs, simply snip the dead flower, leaving the stem and leaves in place. If you see next year’s growth, leave it be.

Now with my dwarf Bloomerang, I want to encourage a second blooming, which should take place towards the end of the summer or early fall. Pruning off the spent spring blooms will encourage more new growth and more blooms for that second bloom time. I could also add a light dose of fertilizer that’s been formulated for woody plants, which will also encourage the shrub to bloom again.
Cut spent flowers after the spring bloom period to encourage a second growth of flowers in the fall.

My dwarf Bloomerang in bloom! Cut spent flowers after the spring bloom period to encourage a second growth of flowers in the fall.

Pruning lilac shrubs

A good rule of thumb when pruning lilacs is not to prune more than one third of a shrub’s stems per year. When one of my lilacs climbed a little too high towards the eavestrough, I simply trimmed those branches to a reasonable height. I then trimmed the spent blooms and called it a day. You can also do a bit of light thinning to encourage new growth.
A more aggressive pruning, perhaps on older shrubs that haven’t been regularly maintained, should be done in late winter or early spring. At this point, you want to cut out older wood and malformed stems, and keep the newer stems to encourage new growth. Cut the older stems down to the ground.
With the Bloomerang lilac, I’ll just trim any especially long pieces to maintain the shape of the shrub. Bloomerangs have a nice rounded habit in the first place, so you don’t have to worry about shaping the bush too much. Mine has been in the garden for a few years and it’s still nice and small and compact.

Removing lilac suckers

Another part of pruning lilacs is removing the suckers. What are suckers? Around my lilac there are a few new lilac trees—single stems a few feet away, shooting up from the soil, making their presence known. These are the suckers. I simply cut them off at the soil line (or slightly below). However stems close to the trunk of the bush itself, you may want to leave, as a healthy lilac has a mix of old and new stems. You could also dig up the suckers and replant them elsewhere. Who doesn’t love new plants?

trimming lilac suckers

Suckers that aren’t close to the actual lilac are simply trimmed at the soil line.

In a pruning mood? Here’s another piece I wrote about how to prune a rose of Sharon.
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Tips for pruning lilacs

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51 Responses to Tips for pruning lilacs

  1. Julie Culshaw says:

    Have you any suggestions for a lilac that loses its colour? I have inherited a lilac bush that bloomed prolifically this spring, but the blossoms quickly faded from purple to washed out cream. Is there something I can add to the soil to help it regain its colour?

    • Tara Nolan says:

      Hi Julie, Have the blooms faded like that in previous years?

    • Kelley E Adams says:

      Tara, this has happened to our bushes as well….Very pale petals, and they hardly lasted 2 weeks (though it was very windy this past month!) I’m a big pruner, but misunderstood the lopping off the flowers when they’re done (I assumed they seeded for the next year)…so thank you for explaining that so well! Also, we do have quite a few suckers…I kinda like them for the green coverage (we have chickens who enjoy foraging with the protection) But I do thin the branches every year, and trim out the little, non-producing twigs so it doesn’t look so woody. A lot of our surrounding neighborhoods have big, even huge lilac bushes! It’s super obvious that none of these homes prune them… And their flowers are so vibrant, and so plentiful!! It’s been probably 3 years since we’ve had such blooms on our lilac… I do not fertilize at all, because of the chickens. And I don’t overwater, either… Our yard is a gorgeous oasis, And everything seems to grow super well for us! I’m just not sure why our lilac blooms have been so lackluster the past couple years… Thank you for any input! I really loved this article!

  2. Melanie Payne says:

    I have a lilac bush that is plentiful on one side and pretty open on the other side. It is about 8 years old and needs pruning. How should I proceed?

    • Tara Nolan says:

      I’m guessing the open side isn’t blooming. A good rule of thumb when pruning lilacs is not to prune more than one third of a shrub’s stems per year.
      A more aggressive pruning, perhaps on older shrubs that haven’t been regularly maintained, should be done in late winter or early spring. At this point, you want to cut out older wood and malformed stems, and keep the newer stems to encourage new growth. Cut the older stems down to the ground.

  3. Amanda Pelyk says:

    Perfect timing! Mine have just started to bloom and they are also getting too high.

  4. Emily says:

    Hi! I have a bloomerang lilac tree and I pruned it tonight. I think I may have pruned new buds by mistake (new Gardner here). Did I ruin the tree from forever blooming again?

  5. Sara says:

    We are finally getting to relandscape my front yard and I have a lilac bush that is in need of trimming. Since it’s September should I wait until March or can I cut it back now. This year it did not bloom anyway due to being neglected for so long. If I cut it back now will it kill the whole plant? I’m not to concerned about gaining blooms right away, mostly just making it healthy again.

    • Tara Nolan says:

      Hi Sara,
      You can remove any dead or diseased wood now, but early spring is the best time of year to prune a lilac bush (if you’re not waiting until after it blooms).

  6. Nancy Melito says:

    Thank you for clearly stating how I should take care of my brand new lilac bush. I’ve checked several websites but no one was as clear and specific as you were, and I’m now sure I can *properly* care for one of my favorite flowers.

  7. Nanett says:

    My 4 yr old bush branches cant support the blooms. Should I feed something in particular. It is @5 feet high and not dense at all

  8. James R Brough says:

    We have a lilac tree which has bloomed on a few branches but the the other branches either have no leaves or flowers or withered leaves and flowers . Should we prune and if so how much. Can you give us some advice. Thanks

    • Tara Nolan says:

      Hi James, Once the blooms have died, I would prune off anything that seems dead or diseased. The leaves curling could be powdery mildew. A little thinning, even of healthy branches, will help to ensure there is airflow through the shrub.

  9. Crystal Connor says:

    Hello,
    New gardener, and new homeowner here. The previous owner has a gigantic lilac tree/bush (honestly its so big im unsure) it does flow over the roof top (one story ranch) and into neighbors driveway. I did not prune last year as i know basically nothing, and still learning tips and tricks. The neighbor said she has pruned her side for years and they are nice so i dont mind. The neighbor side bloomed beautifully this year. The side facing the yard, not so much. Majority (i would say over 50%) of the yard side seems to have no life. There are several bases to it. Over ten trunks from the ground. Is it safe to cut back all of the dead branches, or should i still stick to the 1/3 rule. Im afraid i will kill it and the previous owner is a family friend would not be so happy, nor would my neighbor who loves it, or me because I like it as well and would like to maintain it. Also i noticed on the yard side, the roots seem to be showing, should i add dirt as well?

    • Tara Nolan says:

      Hi Crystal,
      It’s okay to cut out any dead wood from the tree. This will also help with air flow. If roots are showing, I would cover them with fresh soil.

  10. Daniela Velasco says:

    Hi Tara,
    I am a new gardener. I got a house Last year. We have to lilac trees that bloomed this year. But not until the flowering I noticed the trees had a lot of dead wool and old blooms that were never pruned from last years. So, I pruned/cut back a lot of the dead wood that also had some new growing in them. I wish I read this before. That old lilacs might need to be pruned in a three year period of time. I did it all at once today. What does this mean to my two lilac trees? Did I ruined them forever?

    • Tara Nolan says:

      Hi Daniela,
      It’s okay to prune out the dead wood, and after they bloom is a good time to do it. I’d say your lilacs will probably be just fine.

  11. Wendy Lippa says:

    I have one that is not blooming. Should I try pruning it back and seeing if it will bloom next season.

  12. Shannon says:

    We moved into a new house in August 2018 and have two lilac bushes on either side of the house in the backyard. One has produced about 4-5 branches of flowers so far but the other one has absolutely zero flowers. I noticed it didn’t really produce much of anything last year as well. Any helpful insight?

  13. Raaziah Hammad says:

    I bought a Lilac bush 3 yrs ago, it is 5 feet tall right now but it never had flowers. I prune it before winter..does this the only thing wrong I am doing (what I learned from you) or any other thing also. What should I do now so it can bloom next year.

    • Tara Nolan says:

      Hi Raaziah,
      If you prune it before winter, it’s likely you’re pruning off next year’s flower buds. The best time to prune a lilac is right after it flowers, which is right about now.

  14. Anthony says:

    Hello,
    I had a 1 year old lilac plant that was doing great. I had it since it was about 3 inches tall. It grew to about a foot very healthy. I went out to look at it this morning and a squirrel tore it apart. there is still root about i inch down below the dirt. Is there any way I can get that to regrow?

    Thanks

    • Tara Nolan says:

      Hi Anthony, I’m sorry to hear that. I had a squirrel tear apart a mature lilac to build a nest in my chimney! It did grow back, but it sounds as though I had more left. That said, it is very possible that you’ll get some growth from that root that is still there. At the point, it’s kind of a wait and see scenario…

  15. Pat says:

    Hi Tara,
    I have a dwarf lilac tree (I think). It was here when we moved her 6 1/ years ago. I’m trying to become a better Gardner and am wondering about pruning it. I may have waited too long. The tips are brown but when I look under the brown, it’s green. Also there is a gap in the middle of the tree on one side.

    • Tara Nolan says:

      I would cut out the dead bits. If it’s recently bloomed, you can prune, but don’t wait until too late in the season as you’ll risk cutting off next year’s flowers.

  16. Carisa says:

    Hi Tara,

    I have a lilac tree that has green leaves with veins of white in them. Not sure what kind this lilac is. Any idea? Also it is early July and the blooms have been done for two and a half weeks now. Can I prune spent flowers still? Should I wait till spring now? Also seeing green like seeds on spent blooms, what is this?

  17. Tara Nolan says:

    Hi Carisa, I’m not sure what variety you have. You can still prune the flowers. The green seeds are the seed pods produced by the flowers. This is what you can trim.

  18. talia says:

    Hi Tara,
    I forgot to prune few lilac blushes I have.
    they are probably 4 years.
    It is summer, they look healthy, however when can prune them?
    thank you!

    • Tara Nolan says:

      Hi Talia,
      The perfect time to prune a lilac bush is after the flowers have bloomed and faded. Spring-blooming shrubs should be pruned right after they have bloomed. If you save the task for later in the season, you risk pruning off next year’s blooms (because next year’s flower buds form on the current year’s wood)—a mistake I made in the past with an unruly forsythia!

  19. Liat says:

    Hi my Lilac tree has been very healthy until this year it seams to have been frozen. Our early chinook weather made it start to bud and then we got really cold weather. The tree now has some new growth and some branches go leaves. There are many that are dead. should I trim the whole tree back or just cut the dead branches off.
    Advise.
    Liat

  20. Jojo says:

    I have a very old lilac tree. It was here when we moved in in ‘86. It is now to the point where the center woods are almost bare and the tree hasn’t bloomed nicely for the past few years. I had my husband take it down to the ground. I’m hopeful I haven’t killed it for good.

  21. Carl says:

    Hi I have a very tall lilac I decided to cut it down to about 6ft today did I make the wrong move and not have flowers in the spring?
    Kind regards
    Carl

  22. Jennifer Smith says:

    We have lived at our house for just over five years. I knew nothing about pruning my mature lilac bushes/trees. They have bloomed every year, except this year. There were a few buds starting but they never developed into blooms. So, the past couple of nights I have been using my hands to get all the dead flowers off from spring. I have seen several green buds so figured it was for next year. Well, I looked in the center and see several branches that have no free leaves on them. Does that mean they are dead and should be cut? I probably have over 30-40 stems coming up from the ground, or base of the tree. There are probably 3-4 trunks at the base that branch out and up. One Bush is fuller and taller than the other one. They both are at least 8-10 feet tall with the fuller bush almost touching the electrical line that runs to the house. I need to shape them, prune them, and cut them back so they look nicer and aren’t so wild. Also, I have lots of suckers all around the sides of the bushes and hanging over the driveway. I hope I didn’t mess these bushes up by taking off the dead, brittle flowers and the brittle dead branches. There are still a lot of branches that don’t have leaves on them period, just a branch with no stems or green sprouts for new growth. I want to make these trees healthier. These shrubs are probably 10-15 years old. Of course, that’s a guess. I know they are at least 8 based on pictures on the city’s website. Anyway, please, help me or direct me to some resources. I really don’t have much of a green thumb, so to speak. Thanks in advance!

  23. Nadene says:

    Hi Tara Nolan. I have a boomerang. Live 1 hour north of Toronto. It is 3yrs this summer. It is end of September and just noticed the level have brown on them. Almost all the leaves except for the ones near the bottom. It is almost like they were frost bitten. I looked under each leaf and they look healthy and green. Would you be able to explain this to me. Thank you for your time.

    • Tara Nolan says:

      Hi Nadene,
      We had a very hot, dry summer, so it’s possible that the plant has suffered a bit from the drought. It’s also possible it could be a disease, like powdery mildew or bacterial blight. I would search these and see if the leaf images compare to determine what’s affecting your plant.

  24. Julia says:

    Tara,
    I am planning to plant several lilac shrubs toward the end of next month (October), before the ground freezes and I would like to have as long of flowering period as possible in the spring. My understanding is that different varieties bloom at different times, can you tell me what varieties are early, standard, and late bloomers?

    Also, I would like to harvest the seeds to try to grow new shrubs. Is there any particular things I should look for on the seed pods to know whether the seeds are mature enough to harvest? Or would letting the seeds mature take too much energy from the parent shrub?

    Thanks for your help,

    Julia

  25. Nancy says:

    Hi, I pruned down my dwarf lilac bush, it bloomed repeatedly all summer! Was not sure when exactly to prune so did it yesterday. Will it survive the winter ok?

  26. jackie says:

    Hi. I have two lilac plants, both are lovely, but, the bottom half is just dark and woody, would it benefit from trimming right down?

  27. Deanna says:

    I planted a lilacs bush 9 years ago !
    No flowers I prune it every year

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