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.
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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?
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.
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?
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.
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?
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.
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
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.
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?
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.
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?
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?