lilac-opener1EXCEPT IN THE warmest zones, where they are basically disinclined to bloom, every garden should include some common lilacs (Syringa vulgaris) or their various beautiful cousins, old-fashioned shrubs that couldn’t be easier to grow. Given full sun, good air circulation (to lessen the incidence of powdery mildew) and proper pruning, they produce profuse numbers of fragrant flowers. If lilacs fail to bloom, it usually means they have been deprived of sufficient sunshine—or pruned at the wrong time.

Like other spring-blooming woody plants, the lilac produces its flower buds from late summer through fall for the following year’s display. Prune after, say, July 4th in the North and you risk reducing next year’s bloom. Prune in fall or early spring, and you guarantee that disappointment.

A lilac is happiest if you cut bouquets from it each spring—essentially you are just deadheading it. Though not essential to its health or survival, the lilac isn’t really asking much but paying you heftily, since the trusses make extravagant indoor arrangements. You work a little, you win.

A tip: before bringing the cuts inside, hammer the bottom few inches of the stem ends to split them, so they can drink up the water in a vase, or the flowers will wilt almost at once.

Bonus: By harvesting flowers you avoid the unsightly issue of all those large, dried-up flowerheads that hang on tenaciously all year.

Always cut out dead, damaged or diseased wood as it occurs on any shrub or tree, and likewise with suckers that sprout from the base (and may in fact be growing from the rootstock if it’s a grafted plant). Sometimes a lilac needs reshaping.

Conventional gardening wisdom says any shrubs can be “rejuvenated” over three years by cutting one-third of its oldest stems to the base each year, but I ask this: Look at your lilac (or any other shrubs) carefully. Sometimes you don’t want to reinvent (a.k.a. “rejuvenate”) the thing but just to tweak it, so look and think, and look some more before the saw comes out. I like the way Jeff Jabco of the Scott Arboretum of Swarthmore College explains the various stages of the pruning process—whether the yearly flower-harvesting kind or the more ambitious undertakings.

If you want to visit my lilac collection, here it is, and to make your cut bouquets last, read on.

  1. andrewoowoo says:

    Wonderful blog, Margaret! I toured your garden in 2006 and the experience was more than memorable. What a wild and wonderful and vibrant place. Glad I found the blog!

    -Andrew in Ottawa

  2. margaret says:

    Andrew,
    I am so glad you found me so soon! I haven’t even begun reaching out to garden friends–the site’s just 11 days old, and you are among its first visitors. A very good omen indeed.
    M.

  3. andrewoowoo says:

    M,

    I’ve heard from a number of people via my blog – a sort of reader’s appreciation of all things Martha marthamoments.blogspot.com – that they are eager to hear about what you do next. It was one of these visitors who informed me of the site, which I’ll happily promote. I’ve heard rumours from your MSLO peeps that a new book may be in the works, too? I hope so!

    Your guidance of the magazine was truly wondrous, M. dear, but this new chapter seems ultra exciting! Please see my blog for photos of your garden and a rather loving testament to its beauty.

    I’ll be visiting this blog often.

    -Andrew R.

  4. margaret says:

    …and I hope visiting the REAL garden too again someday. Thanks for all the good wishes. We can look forward to spring together.
    M.

  5. margaret says:

    Welcome, Mary Kate. I have indeed heard of ‘Miss Kim,’ which is naturally smaller and slower-growing than many of its cousins. Generally lilacs are pretty tough and adaptable, but seashore conditions (sandy soil, salt air, etc.) can be harsh on any plant. Not sure what’s up with it–growing slow, not flowering, dying off in parts? I assume you have given it a sunny location, which it wants to bloom well.
    Do come back and visit–I will open Q&A forums for formal garden help soon on the blog, and there will be new stories posted every day. Happy spring.
    M.

  6. mary kate mccarty says:

    Hello Margaret,
    I’m a friend of your sister, who was my (superb) writing instructor.
    After visiting the Cotswolds in May a few years ago, I am a passionate novice. Lilacs, peonies and hydrangeas are my favs, and fortunately they seem to do well here in Troy, NY.
    I’m planning to plant lilac bushes soon and wonder if you have heard of the Miss Kim variety? I planted one at my Cape Cod home, and it hasn’t done very well there.

    Your site is amazing – so thorough and comprehensive. I’ve recommended it to some friends who have not gardens but “parks” akin to the Cotswolds, and I’ll continue to pass it along.
    Best of luck,
    Mary Kate McCarty

  7. carl ryan says:

    I have a ? for you, when you pick the lilacs and bring them inside they die so fast, what can we do to slow that dying process down, any suggestions please reply asap, thanks

  8. margaret says:

    Welcome, Carl. The details are in the story on this other page, but basically here’s the trick: hammer the ends of the stems (the woody part) to split it so it can take up moisture. Do this outside on some stones or something.

  9. margaret says:

    Welcome, Bonnie. Lilacs, like other early blooming/spring-blooming shrubs, should be pruned right after bloom. For me bloom ends around Memorial Day or start of June. You get a little leeway after the blossoms fade, before energy goes into preparing to set next year’s buds, which is why I say July 4 is OK, too, but not after.
    When did yours stop blooming? Figure you have a month after that, but closer to end of bloom is ideal/better.
    Once the buds start forming in high summer and onward, any cutting you do will take off would-be flowers.

  10. Bonnie says:

    This is from your article “Prune after, say, July 4th in the north and you risk reducing next year’s bloom. Prune in fall or early spring, and you guarantee that disappointment.”
    Sooooo – when is the best time to guarantee blooms in the next year. (Eastern Ontario, Canada).
    I see wild lilac blooming profusely in ditches but not my pampered ones.
    Thanks Bonnie

  11. margaret says:

    Welcome A in Calgary: There is never a bad time to apply compost and mulch, but better not to apply actual commercial fertilizer at this time. Good that you seized the day and got on with your pruning, even now…since you had the time. I know how that goes!

  12. a in calgary says:

    Lacking time previously, I’ve just spent a week pruning my lilacs. Some I have taken care of well over the years ..so it was just taking off suckers… But there are some that I left unpruned for several years.. really old lilacs + 50 years old with stems from 3 to 1 inch. These are doing poorly…there was so much deadwood. +60% I had left it there to test a theory that the dead wood would provide support during our very heavy spring snowstorms. But now there was so much that I was alarmed. I know its late in the year to prune but I’m looking ahead a few years… I know its late to be feeding our first frost can come within a month Ha Ha .. but it won’t last.. These lilacs have never been fertilized or even watered much unless there was a severe drought… Is it too late to put a layer of compost down and cover it with mulch?

  13. Anita says:

    Looking for extremely fragrant lilacs. My yard is small, so I tried Miss Kim – no fragrance at all!! Recently bought Tinkerbelle so hopefully this spring will have fragrance. Any other suggestions for fragrance?

    1. margaret says:

      Welcome, Anita. Yes, ‘Miss Kim’ is a nice size but not sweet to the nose. Did you see the collection of them I posted about last spring? All of those are fragrant, though some are quite large. If you like pink, ‘Marie Frances’ might fit your space. Have a look, and let me know.

  14. Chris Anne says:

    We have nine Miss Kim lilacs, and they are so sweetly fragrant that they just about knock us over. Maybe we have mutants? I actually came searching for pruning instructions for these at my DH’s request, (from whom I must hide the loppers till late spring, as he gets cabin fever about this time of year and is wont to go out randomly hacking) . The MK’s were planted 4 springs ago, and are looking just a bit ragged. They are not in full sun except in early spring, but this hasn’t seemed to discourage blooming, thank heaven. Was just surprised to read that others haven’t found them fragrant.

    1. Margaret says:

      Welcome, Chris Anne. It is interesting about fragrance and how sometimes it is so heavy and sometimes not. Everything I read in reference materials says it’s meant to be fragrant, and apparently you agree. See you soon again, I hope — and tell the DH to watch out and not turn Miss Kim into a blob over there. :)

    1. Margaret says:

      @Carol: I think rabbits will eat most anything. The only prevention is a barrier to keep them out of/away from the plants, and with rabbits that means not just fencing or mesh of some kind (preferably wire) above ground but also tunneling-prevention beneath the soil surface. On this page on the Cornell website, scroll down to the rabbit section and get the PDF factsheet about rabbit prevention for details. (Note that it s multiple pages and the diagrams and such are not on the first page…keep clicking.)

  15. elena says:

    Have you had luck with moving lilac bushes? We will be rebuilding our house and the current location of 3 very mature lilacs are in danger of being ‘dozed or trampled. I’d like to put them in large pots or boxes for about one year, then replant. Is this a good idea from your perspective?

    1. Margaret says:

      Welcome, Elena. I would not plan to pot them (the pots would have to be the size of a bathtub!) :) but maybe “heel them in” (meaning plant them somewhere temporarily) instead. Also, you will probably want to cut them back substantially to help them with the stress of the move.

      You say very mature, so hence my thoughts about the pots. Also, much harder to keep a plant unstressed above-ground in a pot, where its roots bake all summer, than in the ground. Boxes would be ok if enough soil volume to protect the root systems, insulating them with a good amount of soil.

      Again, I suspect you will want to reduce the topgrowth to offset root disturbance — at least cut out oldest stems to the ground, like one-third of them, I expect. Very hard for me to judge without seeing them as you can understand.

  16. Denise says:

    Hi Margaret,

    I have a question about pruning lilacs. We inherited a beautiful lilac bush when we purchased our home. It is at the edge of our walkway and at the corner of our house, so it is limited in how much it can grow. I have to prune it every year because it extends out too far into our walkway. I have noticed that the outer branches are very thin where the lilacs bloom each year. There is a clear demarcation, however, about a third of the way into the center of the shrub where the branches get much thicker and there is much more open space in the interior of the shrub. I have limited myself to pruning only the thin branches at the margin of the shrub each year because I am afraid that it won’t bloom again if I cut in too far. However, the plant continually blooms into the walkway, so it seems I am in an endless cycle where I can’t seem to get the plant cut back far enough.

    Do you have any suggestions for me?

    1. Margaret says:

      Welcome, Denise. Other than those suited to hedging, relatively few shrubs love being cut back to be kept in scale — and they look pretty bad when they are, especially if it’s done repeatedly. What you have is too big a plant for the space, and it would be better to replace it with one that stays smaller…or to cut the oldest stems down to the ground and let younger ones grow up, rejuvenating the entire shrub, rather than to create this sort of pollarded (read the definition/see pictures here) lilac with partway cutbacks.

      Whether it will bloom depends on when you prune (best to do so right after bloom to prevent taking off any flower buds). To rejuvenate the shrub, cut out about a third of the stems each year right near the base, starting with the oldest ones (especially those thickened ones). It’s extreme, but no other way to get a shrub of the size you want…and you will have to do this again after it outgrows the space again. Might be easier to get a different shrub for the spot.

  17. Lisabeth Davis says:

    My mowing and fertilizing sheep pruned the lilacs last summer so no blooms this year but we are doing a better job fencing them (the sheep) this year. I am trying to consolidate some planting beds so that it is easier to fence the sheep out – this ad hoc creating a garden from wilderness has its limitations.
    The weather went from a low of 34 on June 1st to a high of 95 yesterday!

  18. Peterpepper says:

    A Miss Kim is truly in the shade now — nonexistent blooms — after having been moved from a sunny but too tight corner. What were we thinking, etc. So, having chopped three forsythias down last month and (soon) out, a sunny space becomes available for next spring, just right for a lilac. What prep to the lovely MK should we do now (June 7, 2010) to prepare it for fall move? Is root reduction in order? No blossoms, so how does one prune?

  19. Joan says:

    I had a beautiful but very old Lilac bush. It has bloomed nicely the past few years but has also grown out of control. I talked with my lawn guy and asked him to prune it. We talked about how much. It was about 14 ffeet high and my understanding was that he would prune it down to about 9 feet high.. I came home today to find it pruned down to maybe 2-3 feet high. I am sick about it. Not a leaf on what is left. I’m guessing it will be years before I see any flowers and am heartsick over this. What is my best case scenario in this situation? My understanding is that severe pruning should be done in late winter/early spring. How will this severe pruning in June affect the future of this bush? I’m guessing I’m looking at losing 5-7 years of blooming. Am I right? I hope not.

    1. Margaret says:

      Welcome, Joan. You can’t “top” a lilac and have it grow out gracefully, so it’s actually better to cut down the oldest stems to the ground, a third of them a year, to rejuvenate it. Sounds like this person went a little wild. But cutting off 5 feet to bring it to 9 would not have worked, either.

      I would do this: Keep it well-watered and maybe even feed it (right away — not later in the summer) with a formula rated for shrubs. I suspect you will have blooms in a few years again.

      The one thing I am wondering about — 2-3 feet? Hard to tell without seeing, but I often go even lower when I take out old stems so that the new growth comes gracefully from a low base. So often things come out down to a foot or below, but there may be a reason that he left that much…hmmm….

      The moral of this story is that “lawn guys” are not tree and shrub guys, generally speaking. :)

  20. Jani Allen says:

    What a nice column you have written for us!!

    A new Gardner I am…and I have a new little lilac bush that has been in the ground for apx. 5 years. No growth, no blooms, no joy…yet!

    I planted it at that time in acidic soil. Since then I moved it to full sun, amended the soil, and behold!, it has healthy new leaves, new growth, but no blooms.

    It is about 2 feet tall. Should I prune it? If so, what should I prune? How long should it take to bloom (I am 73!!!).

    Thank you so much for your information!

    Jani

    1. Margaret says:

      Welcome, Jani. If it is still small don’t prune (unless to remove any dead twigs) but first let it grow up to blooming size. I don’t know the variety or anything but it would seem if it can now just settle in, have sunshine, be watered to prevent drying out and so on, it should bloom in the next couple or few years. You will be able to tell this fall, if you see little dormant flower buds forming on the tips. The flower buds start forming a couple of month’s after this year’s bloom finishes, or around July in the North where I am. Never prune in summer and beyond or you will cut off any of next year’s flowers-to-be.

  21. Katie says:

    Hi Margaret!

    I am wondering if pruning a lilac tree is any different than a lilac bush. We have two small lilac trees in front of our house (we bought the house in December…the trees appear to have been planted last year). One tree had lots of blooms and little leaves this summer, and the other was full of leaves with only a few blooms. Can I just cut the branches back to shape the trees? Or are there “rules” for this sort of thing?

    Thanks!
    Katie

    PS-The more flowery of the trees lost a few limbs when a large branch fell on it! I am hoping I can get it replaced…flowering trees are just so beautiful!

    1. Margaret says:

      Hi, Katie. There are tree lilacs, such as Syringa reticulata, with bronzy shiny bark and creamy flowers, and then there are shrubbier forms of lilac (from the more familiar species S. vulgaris or S. hyacinthiflora) that include some varieties that are more upright and some more bushy. Need to know what kind we are talking about here. If they were just planted a year ago, whatever they are, the uneven flowering may just have been a result of settling in after transplant disturbance. (I’m more concerned about the one with “little leaves”.) Do you know what they are — flower color? Is the bark anything special or just your basic lilac?

  22. Ruth says:

    Hi Margaret … I have a lilac tree that has bloomed beautifully for at least 7 years. This year nothing. I’m unsure of the type but it produced a 2 tone purple bloom and was so fragrant. We are wondering if we pruned it too late last summer (we live in Fort Erie south western Ontario, canada) and possible cut off the blooms.
    Moving forward what would you suggest we do to improve the chances of getting our beautiful bloom back?
    The tree trunk is about as thick as a womans wrist and there seems to be a bump in it so maybe it was grafted onto this trunk … there are 4 main branches off the trunk with a good number of shoots off each branch. It has leaves but no blooms.
    If you recommend prunning can you tell me when and how (or direct me to this information on your site please)
    thanks and looking forward to hearing from you
    Ruth

    1. margaret says:

      Hi, Ruth. You are on the lilac pruning page! Don’t prune after about July 4th — and really it’s best to prune right after bloom, before any flower buds for next year are set. Later pruning will indeed cut off next year’s flowers. My pruning primer page for all matters pruning-related is here.

Leave a Reply

Your email address will not be published. Required fields are marked *

This site uses Akismet to reduce spam. Learn how your comment data is processed.