from the forums: pruning viburnums

WHEN TO PRUNE VIBURNUMS? That timely question was raised this week on the Urgent Garden Question Forums. “When is the best time to prune large viburnum shrubs?” asked Forum member ZSteinberg. “Two are double-file, three are American cranberrybush and I don’t know the names of the other three. Any general recommendations?”

I have grown a lot of viburnums over the years, and have pruned them at various times of year for one reason or another. Usually viburnums need relatively little pruning, assuming you planted the right cultivar in the right-sized space (for example, not ‘Mariesii’ among the doublefiles, shown, but ‘Watanabei’ if you only had a smallish area). Even the lightest form of pruning, the removal of spent flowers called deadheading, isn’t needed with most viburnums, since what you want is fruit after the flowers (unlike all that deadheading with lilacs, for instance, to prevent messiness).


POOR PLANNING TO BLAME

Most of the pruning I’ve had to do on viburnums was because I didn’t leave enough room for the plant to reach its eventual size, and poor planning (meaning my impatience to have a filled-in garden) caught up with me in time. I have cut several viburnums to the ground or thereabouts in very early spring, when they simply got too big for where I had placed them, and let them re-grow. My list of successful such butcher jobs includes the European cranberrybush (V. opulus) and its American counterpart, V. trilobum, and various leatherleaf viburnums (V. rhytidophylloides and rhytidophyllum). Some have had this treatment twice already in their lives with me. Poor dears.

But if all I really need is a little fine-tuning or gentle re-shaping, which is the norm, I time my cuts right after bloom. That gives the plants time to regrow and potentially set blooms, even, for the following year (depending on how far down I cut on which kind). Except dead, damaged or diseased wood removal, I do not prune anything hard late in the season anyway, viburnums or otherwise, letting the new shoots from spring pruning harden off and prepare themselves for winter (then letting winter first do its thing, which can sometimes be the catalyst for pruning if ice or heavy snow load snaps twigs).

Generally speaking, you are not shearing the plant but cutting back judiciously to just above a node with each clip of the shears so the plant can make new shoots in a somewhat natural-looking style. Of course always look for suspiciously vertical new shoots that jut from the base—stems that look unlike the rest of the plant, and like they couldn’t ever fit in. Remove those as they develop, which I find that they do once a doublefile or leatherleaf viburnum, in particular, gets to a certain size. Also watch for any vertical (again, suspicious-looking) water sprouts off the main branches, which I have had from time to time, more on V. sieboldii than others I think. See my basic pruning tips for a primer on this kind of stuff.

Again, easy does it.

“Viburnum pruning should be an exercise in restraint,” writes Michael Dirr, the famed professor of horticulture from the University of Georgia whose “Manual of Woody Landscape Plants” is the standard reference. Those with a particular interest in what I think of as the finest genus of shrubs (read why I say that) may want to Dirr’s recent book, “Viburnums: Flowering Shrubs for Every Season.” Hopefully, he’d forgive me treating the occasional member of the genus as a cutback shrub after goofing with my garden designs, just like the viburnums did. Mea culpa.

53 comments
June 3, 2008

comments

  1. Ellen Shelly says

    I am part of a homeowner association that last year planted 45 viburnums not for their flowering to provide a barrier between our property and a highway. To keep the plants from becoming leggy how often should be have them pruned?

    • says

      Welcome, Ellen. As the story says, basically no need to prune in most cases, so less is more on the pruning front. They really are not the kind of shrub that like to be shaped into a certain height or form; they are more loose and natural-looking. I would not recommend regular shearing, but rather allowing them to be what they are. Not sure which species/variety you have…many different forms and shapes. Let me know and I can try to be more specific, but viburnums are not the choice when one wishes to shear tight or hedge-like. Hope to see you again soon.

  2. woody plant girl says

    Maybe off topic but I’ll shoehorn it in because of the viburnam mention and planting too close together, etc.
    It has taken me 20 years, but I have completed eliminating all grass on my 1/3 acre sloping lot and my front yard is now awaiting planting in my stone terraces. On either side of the flagstone steps leading to the front door, I’m thinking about using the Viburnam ‘winterthur’ or nudum. I like the leaf shape and color. I’d imagined a rather vegetative Japanese bridge like effect in autumn. The upper garden planted 15 years ago is an ode to spring, I’d like this new lower garden to be green in spring and awaken in fall and look handsomely stalwart in winter. If you think is ok, how close together. Not quite hedge, but seriously together. Other ideas?

    • says

      Hi, Woody Plant Girl. I love ‘Winterthur,’ and I suppose you could plant them on 4-foot centers, as they get about 4 feet wide. A great plant.

  3. aneyefordetail says

    Question re. Viburnums: We have a “Carlesii” (think that’s the correct spelling!) This year it had maybe, at most, four flowers… we had cut back last year, in the spring. It is just too big for where we have it (right against the house, in front….) so I can’t just let it grow! Should I try cutting way, way back right now, and hope for some flowers next spring? Or, I guess I should think about moving it. And, should I prune it radically, rather than just clipping here and there? Take out some major stems?

    • says

      Welcome, Aneyefordetail. Pruning isn’t going to make the plant fit the space, I am afraid…it will just make it lumpy and lopsided and a mess. It needs a new spot (but may be too big to move easily, I don’t know). When you get it out of there, don’t plant something else near the house; stay farther out next time. I have never cut a ‘Carlesii’ to the ground to start over, nor moved a big one. Partway cutbacks just don’t suit viburnums, which really like to be left pretty much alone as the article mentions. So this is a wrong plant/wrong place moment…move it, or cut it down and give up on it I think.

  4. sarah says

    My 6 year old snowball viburnum was pruned last year, and seemed fine we had a late frost that damaged all the blooms. There are no leaves and all buds are dead on the branches. What to do? Also have a 3 year old one that has had no pruning, but suffered damage during the frost. It has a few branches with leaves.
    Thanks

    • says

      Welcome, Sarah. When frost hits a plant, I never do anything until the plant tells me what’s up (whether it plans to recover or not). By that I mean does it gradually push out new buds somewhere, or start regrowing from the base, or just up and die? Do not feed….do not prune again until you know if the twigs are still alive (I’d wait a few weeks more); just water and watch. Normally new growth will push out once it catches its breath, so keep an eye out.

  5. Christie says

    So glad to have stumbled onto this site! We have a viburnum that is entering it’s 4th year in our yard. The first year it had 4 blooms, the second it had about 10, this year it was absolutely covered with big, beautiful blossoms but only a few leaves followed and they never developed fully. What is wrong, what should I do?

    • says

      Welcome, Christie. Let me make sure I understand: Lots of flowers, but then few leaves developed? Or is it the fruit that didn’t follow the flowers? Or??? Any chance the leaves were eaten, as mine were on some shrubs early this spring by viburnum leaf beetle larvae? Just want to make sure I am picturing what’s happened correctly before answering.

  6. Joe De Stefano says

    My viburnums ( a couple of varieties ) have become very top heavy and sparce from ground level to about half way to their height . I have them for a border and need to trim them so as to promote closure foilage in the bottom half of the plant . When is the best time for what would amount to a minimum 1/3 sized pruning for this year?

    • says

      Welcome, Joe. Viburnums generally don’t take so well to partial pruning. You can read about it here (scroll down a few questions). Whatever you do, better to wait until after the winter, so more like March or April (I don’t know what zone you are in). They normally don’t get bushy in a nice way from the kind of pruning you are pondering. Do you know what caused the lower areas to die off?

  7. Evelyn says

    I would like to plant a fast growing shade tree,do you have any suggestions?I live in NewJersey(South Jersey) to be exact.I need shade fast.Husband cut all the trees down for safety reasons and work.I need a tree.Happy gardening .Evelyn

    • says

      Welcome, Evelyn. Now that’s a good question…but there’s no good answer. Yes, I know some fast-growing trees…but a lot of the quickies are also sort of junk-y…they don’t add up to much in the long run (or even live a good long life). You could have fast shade from Catalpa or Paulownia or Mimosa or (etc. etc.) but I say don’t do it. Invest in a good, long-lived shade tree, and start with a good-sized plant to give you the “fast” start.

      I will say that even some really nice medium-sized trees like Kousa dogwoods get off to a good start if you buy a good-size unnamed seedling (pretty fair price if it’s not some special variety).

      How tall do you need the shade — to cool the house, or a one-story porch, or simply a garden bed? Let me know so we can figure out what will work.

  8. Joanna says

    I adopted two rhoddies in a lovely red color. They are maybe 4′ high and had lived tight against a house. So one side has wonderful blooms and the other side is woody. I was thinking of putting a double file viburnum behind them to hide the woody side and to give a little more interest. I would not want the new plant to grow much beyond 5 to 6′ …..so a double file may not be the right choice. Any suggestions? Joanna

    • says

      Welcome, Joanna. There are smaller doublefiles, though sometimes with snowball (instead of lacecap) flowers. The one list I found detailing some large and small that you can start from and work deeper in a little research is at the University of Connecticut site — here are their doublefile viburnum descriptions.

      One caveat, though: Do not choose one that gets bigger and expect to “keep it in bounds” by pruning. There are also some scaled down versions of panicle hydrangea, H. paniculata, like ‘Little Lamb’ if that is the look you are after.

  9. vhfmanager says

    I am a manager of a homeowner’s association in Central NJ and I have noticed that the leatherleaf virbirnum in the community appear to be dying. Our landscaping company recently, in very late June and early July pruned these shrubs. They pruned with electric shears and shaped them. There is no watering system in the community and it’s been a particularly hot June and July, so far. I’m concerned that they damaged these shrubs by pruning them in such hot temperatures. The shrubs that they just pruned last week are showing brown on the tips all around. I expect that in the next couple of days all of the leaves will turn brown and fall just like the virbirnum they pruned in late June. I’ve never seen this happen before as they’ve always pruned in early to mid June. Any advice?

    Thanks.

    • says

      Welcome, VHFmanager. I think that must have been very stressful to be pruned in this heat; I agree with you. I would never prune a viburnum with hedge shears, anyway….but I wouldn’t prune anything in the brutal hot/dry of late. They need water and for you all to cross your fingers. There will probably be some cleanup needed to remove the brown tips/dead stuff that results, but for now I’d just water well, and watch. (I assume even though there is no irrigation system you can get lots of water to them somehow?) One more thing: NO fertilizer!

  10. mary grad says

    I have two new viburnum in my back yard. Both have grown exceptionally well. At this time, one plant is touching the house. I wanted to know when to prune. From what I have read, I think I need to wait until fall. I did not prune the blooms in the spring. I now have red berries.

    • says

      Welcome, Mary. They don’t really love trimming to keep them into some size and get rather misshapen from that. They should probably be moved farther from the house while they are young-ish, rather than plan to have to chop them partway down again and again. They just aren’t a plant that responds well to that.

      In My pruning FAQ page I summarize how to handle them. The link is here. I usually do it in spring — either early, just as growth begins, or right after bloom. But again, I don’t cut halfway like I’m prunign a hedge. Have a read.

  11. Ann says

    I had a mariesii and 2 shasta viburnums, about 5 years old at the time, out in full glory when we had a hard freeze (Zone 5). That was 3 years ago. The shastas didn’t make it. The mariesii is growing, but it has never come back to its beautiful horizontal shape. There are spaces with no branches and a several vertical branches close to the center of the shrub. The top of the plant is slightly better than the lower 4 feet. Is there anything I can do to help this plant back to its original beauty?

    • says

      Welcome, Ann. I know exactly what you are talking about — in the way that the doublefiles (and most viburnums, frankly) don’t respond well to pruning back partway intentionally, they get very misshapen from such damage. The very vertical shoots you describe from the base should probably be removed completely — unless you can imagine them shaping up ever as well-placed branches, but I doubt it.

      Scary but true: I have had better luck cutting misshapen viburnums right near the ground in late winter and letting them regrow from scratch that with trying to correct after substantial damage. With a doublefile, though, I have had the worst luck of all in regaining that desired shape, sad to say. Cranberry bush types or some of the other more vertical growers (V. setigerum, some of the leatherleaf types) are easier to rejuvenate from the ground.

      Might be time to start over with a new plant, sadly.

  12. Phoebe says

    I am disappointed to read about your doublefile pruning. I inherited three doublefile viburnums when I bought this property and they are now huge, probably 12 to 15 ft. They block the entire view of the front yard. I trimmed them back 1/3 two years ago and they came back bigger than ever. They have put out runners along the base which have turned into even more shrubs. I tried to dig out the spreading bushes, but evidently didn’t get all of them. I was going to try and cut the main bushes down to about 2 ft in February or March and let them start over, but after reading all of the above, I’m not sure what to do now. Any suggestions would be appreciated.

    • says

      Welcome, Phoebe. The thing *not* to do is cut them back partway…I think they respond really badly to that, especially the doublefiles, with their inherently horizontal-ish branch structure.

      You can let them start over, as you say…but really, the problem is: wrong plant, wrong place. They will be 12 or 15 or more feet again in time, and then what? If you want a doublefile, pick a more dwarf variety…or choose another plant that suits the space better and stays small enough even at maturity to not block the view. Hard but I have been though this many times — I am removing a lot of things here that after 20 years have just outgrown their spots.

  13. Jackie says

    It occurs to me to prune at the end of the summer when everything looks too full or too large after a summer growing season. Is this bad?

  14. Nancy Griffin says

    An online article on Viburnums in Fine Gardening shows a picture of a viburnum and states …”V. plicatum var. tomentosum ‘Mariesii’ that’s been pruned into a low-growing form”. I love the shape and was hoping to train mine similarly, however, reading your article and answers to questions, I’m assuming that I should not try to shape this young viburnum? I do have this variety and it is a couple of years old, just starting to gain some vertical growth in a rather uneven way. I did notice several of the vertical shoots that I can eliminate based on your information.

    • says

      Welcome, Nancy. You can always remove whole limbs (I assume they took out the most vertical “leader(s)” early on), but what I am saying is you can’t have a nice shape by continually cutting branches back part way. So shearing a grown plant won’t yield what’s in that Fine Gardening photo; early training and subsequent removal of any new branches that try to go vertical (removal, not partial trimming back) will keep it somewhat smaller and more horizontal. So yes, go for it now, early on.

  15. C.A. Smith says

    I have a home in the mountains of western North Carolina and I think we have some viburnum bushes – they have Viburnum like flowers in the spring/summer – now the leaves are gone are the branches/shoots are a cranberry red color. Is this Viburnum and if so, which one? Thank you!!

  16. KMG says

    We have recently planted non-flowering viburnum shrubs in the hopes of growing a privacy fence. In order to make them fill in, we were told to trim them about 1/3. Is there anything special I should know before I start trimming? Thanks so much.

    • says

      Welcome, KMG. All Viburnums flower, unless you cut off the buds each year with the kind of pruning you are suggesting. As per the article and my Pruning FAG Page, I don’t recommend it…it creates really misshapen shrubs (that don’t bloom or set fruit — which is why I grow Viburnums). But…you want a hedge, so maybe that’s OK for you. But what species or variety are we talking about?

  17. Karla says

    Viburnum davidii….what is the correct way to rejuvenate a shrub that is leggy? Can it be donwn in one fel swoop or should it be done in stages?

    Thanks!

    • says

      Welcome, Karla, and how lucky that you can grow this beautiful shrub. (Not here.) Its natural habit is graceful, low-ish, mound-like, so if you cut away at it here and there I think (as with may Viburnums) you will lose that and maybe even expose the leafless parts in the middle. If it’s really out of shape I’d rejuvenation-prune it (down low) and let it regrow. I’d time this for late winter/early spring. I can’t see the plant and maybe a little corrective pruning can help…but oftenwith Viburnum that’s not so easy.

  18. Bonnie says

    Hi, 3 summers ago we planted 3 Blue Muffin Arrowwood Viburnum schrubs and we get plenty of flower clusters but they have never grown any berries, what do you suggest? I planted these in close proximity of each other and got them because they attract songbirds but 3 years in a row now and no fruit. Thank you

    • says

      Hi, Bonnie. Viburnums need a pollinator that’s usually a close cousin, but not a duplicate of the very same variety. Another variety of V. dentatum (arrowwood viburnum) is needed, and ‘Chicago Lustre’ is particularly recommended.

  19. Bonnie says

    the local greenhouse sells Onondaga and Fragrant snowball viburnums, will these pollinate my blue muffins?

  20. Mary says

    I have an established dwarf mariesii viburnum that has always flowered, but this year it didn’t. I live in Illinois and we had about 2′ of snow and it was a hard winter, so I’m wondering if that’s what caused this. I don’t prune on the bush unless I see some dead branches. It looks fine otherwise but perhaps I should be looking closer for some ‘critters’. I fertilize it in spring and summer with 10-10-10 fertilizer. Any suggestions would be appreciated.

    • says

      Welcome, Mary. Typically no flowers on things mean too much shade, too much Nitrogen fertilizer (which makes for foliage not flowers), improper pruning (doesn’t sound like your issue), or bids killed by severe weather (though I never had even a very cold winter do that to my doublefiles — how cold did it get?). I lost yet another doublefile this year to a fungal disease/canker that causes dieback, which you can read about here. You’d see gradual loss and lack of vigor in some of the branches, and peeling bark and so on as the link shows. Hopefully it’s just a fluke because of the winter as you say, if the plant looks otherwise healthy.

  21. Mary says

    I’m afraid it’s the disease. I cut off a small dead branch on the inside of the plant and when I pulled the bark back it was moist brown sort of sooty stuff. I broke the same branch in half and the inside was clean but the outer layer was that brown sooty stuff. The bush has new growth and looks great otherwise. Do I just wait for it to die. I read that there’s no treatment for it. do you think I should continue to fertilize. I feel kind of sick about this.

    • says

      I feel your pain, Mary — for me the doublefiles are the ones that succumb to this and I don’t know why (beyond what I shared in the link). I had one die pretty fast after showing the first signs, and another go on for years (prune out the affected parts, dipping your shears or other tool in a bleach solution or alcohol between cuts). I don’t know if fertilizing will help or hurt, frankly. For me the worst thing has been my fear now of adding a new doublefile to the landscape — they are among my very favorite shrubs, but I don’t think I can have them here any more (sort of like Cornus florida, the native dogwood — I can’t keep them alive or at least healthy looking here because of the fungal disease Anthracnose). I will do more homework.

  22. Mary says

    Okay. Here’s what I’m planning to do based on what I read in the article you sent me, which I want to thank you for very much. I’m going to get into the center of the plant and start pruning out all the dead branches. I am dipping my pruners in straight bleach. Is that ok or should I use achohol? I’ll see if I can prevent the disease from spreading into the healthy part of the plant unless that’s already happened. Also, about 8 feet away I have viburnum opulus ‘nanum’ bushes growing which were diagnosed with canker about 15 years ago, but I pruned out the dead stuff and they are doing fine today. Could they be affecting my mariesii?

  23. Mary says

    I’m sorry to be posting so soon again. I just had a thought. The canker on my “baby viburnums” was like a ‘narly” growth, not like what I’m seeing on the mariesii. I took out dead sections of those bushes and disposed of those in garden bags put out for the trash.

  24. Lee Williamson says

    I live in western Washington state and have several Wentworth viburnum that grew really well this year and have sent up some long vertical shoots from either the base of the plant or from some branches. Will these develop into desirable branches or should they be removed?

    • says

      Hi, Lee. Here, too! With the water sprouts (vertical shoots off the branches) I always remove them — architecturally, placed so vertically and at a 90-degree angle from the branches, how can they ever amount to anything productive? With the suckers from the base, I am usually inclined to get rid of them unless I have a declining branch on the plant that one of them might replace (if it’s positioned well) but usually they, too, are just a mess that overtakes the shape of the plant. More pruning info is on my FAQ page.

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