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Learn how to prune rhododendrons & azaleas:
If you want to learn how to prune rhododendrons, we’ve got you covered. And we’ve even included visual steps for deadheading rhododendrons too.
Plus, the good news is, you can fine-prune these beautiful plants just about any time of year. But, that’s only true if you take care not to cut off all the flower buds.
Let’s face it: sometimes you get to pruning when you have the time. And not every plant can be pruned successfully at the same time as every other plant.
But rhodies are quite forgiving on timing your pruning cuts.
When should rhododendrons be cut back?
- Don’t prune rhododendrons if they are flowering. Except if you want to cut a few flowers for a vase.
- Don’t prune if they are just getting ready to flower. That’s because you’ll miss the best of their blooms.
- Don’t prune rhododendrons if it is frozen outside. That’s because you can easily break a branch.
- And, remember, if you hire someone who wants to shear your plant in February, odds are they’ll cut off all of your spring rhododendron flowers! That’s because the plant has already grown these flower buds in order to bloom a few months later in spring (or thereabouts).
- If you’re pruning rhododendrons in spring, summer or autumn, be sure to check for hornet nests. That’s because they love to build their summer homes in rhodies. And this is extra true of neglected plants.
- Watch out for nesting hummingbirds and other birds in your rhododendrons. (If you love hummingbirds, check out this peek video of them nesting in the flowering rhodie shown here.)
Some pruning rules are made to be broken.
And your garden and plants may require a bit of rule bending. But generally speaking you can follow these rules to trim rhododendrons after they bloom. As well this will help you rejuvenate an old leggy rhododendron. Plus, when you prune this way, you may not end up asking if rhododendrons can be cut back hard!
Most importantly, if you don’t know how to properly prune woody plants, join our online gardening classes for step-by-step lessons in how to prune all kinds of plants.
Before we began, this foundation evergreen rhodie was filled with dead branches on the interior. And, it had lots of deadheads to clean too.
And you will need some basic tools to prune a rhododendron…
- You’ll need a pair of bypass pruners.
- And, a folding handsaw.
- Plus, a tarp will come in handy when you prune your rhodies.
Before pruning, this rhodie had lots of interior dead wood. To make cleaning up all the detritus we would be cutting, we spread a plastic tarp underneath it.
By the way, did you know that all azaleas are rhododendrons?
Yep, Rhododendron is actually a genus of plants into which the azaleas are also classified! So, it makes sense that learning how to prune rhododendrons means learning how to prune azaleas too.
But, generally speaking, azaleas are twiggier than rhodies. So, for azaleas you’ll probably be making a lot more small cuts than you would on bigger rhodies.
Fine pruning these plants means you don’t shear them.
Shearing means cutting only the exterior of the plant. And that means you’d be ignoring dead materials.
Plus, when you shear, you usually end up creating even more dead branches on your shrubs.
In fact, one sign of a good pruner is you can hardly tell they’ve cut anything from your plants. And, the plant don’t look like heavily manicured, unnatural shapes.
However, fine pruning leaves our plants in better shape inside and out.
When we clean up the interior of the plants, sunlight and air flows through them. And this helps reduce pest and disease issues in many garden situations.
Moreover, done right, proper pruning reduces long term maintenance. And it leaves your plant looking natural.
Plus, you’ll probably really enjoy the gorgeous rhododendron bark too when you can finally see it!
This rhodie has been fine pruned on the interior. And, the deadheads are gone. It almost looks like nothing happened. And, that’s a good sign.
Next up: a visual guide to deadheading your rhododendrons.
First, it’s a total myth that your rhodies won’t bloom if you don’t deadhead them. In fact, rhodies will bloom abundantly even if you never remove a single deadhead.
But, you’ll have to look at those ratty seed heads all over your evergreens throughout the growing season. And you’ll be looking at a jumbled mass of dead material piling up in the interior of your plant over the years.
So, removing pruning rhododendrons to remove deadheads is really an aesthetic choice.
However, it is not a critical pruning move in order to keep rhodies flowering.
Here’s how to deadhead Rhododendrons after they flower:
After a rhodie has bloomed, grip the old flower head between your fingers. And take care not to damage flower or leaf buds or stems surrounding the old parts.
Next, bend the flower remnant from between any new growth. And do this by hand rather than with clippers. Plus, you might want to wear gloves so your fingers don’t get sticky.
Usually, rhodie deadheads snap out easily & cleanly. But if part of the deadhead remains, pinch that out as well. Or snip it clean with your hand shears.
And one final reminder on how to prune rhododendrons…
Before you make a cut, it is important to recognize the plant’s different kind of growth buds. That’s because a flower bud from leaf is different from a stem bud.
So, if you recognize the difference, you can easily avoid cutting off flowers. Moreover, this should help you consider when rhododendrons should be cut.
What does a rhododendron flower bud look like?
Pruned and deadheaded properly (or even not at all), rhodies and azaleas can live for many generations. They provide evergreen interest during the dull days of winter, a blast of spring color & pollinator forage in every color of the rainbow, and they provide the backdrop against which summer & fall color will glow.
The idea that it’s okay not to deadhead at all, or to do it imperfectly, makes this the best rhodie pruning site I’ve found. The suggestions for cleaning out dead wood and removing crossing branches (to open up the interior) are good, too.
I’m left with one question: how to handle new growth. A couple of my rhodies have new branches shooting up a foot or two (often from places where a new flower would have been nicer). Is there a way to cut those back to promote more flowers?
David,
Thanks for your kind comments. Glad we could help. Pruning back shoots may not help stimulate flowering buds. If the shoots are getting long and leggy, you could try to cut them back or thin them to encourage the shortest, stoutest in a cluster. But, look to see if any have put on fat terminal buds that will be the flowers for next year. Too, you could cut back the long shoots and try to encourage new, shorter growth. Forcing a flower bud may be tough. Sometimes cutting back hard means waiting a couple seasons before you’ll get those flowers you’re looking for. Good luck!
Have been told that when pruning larger branches (over 1/2″) it is wise to treat the cut area with a water type glue – like Elmers wood glue – to prevent bugs and disease. Comments please. thanks, Dave Walters
I have been told that when pruning Rhododendron’s it is wise to cover cut area with a water type glue to prevent bugs and disease. Elmer’s wood glue was recommended. Comments please. Thanks, Dave Walters
Dave, Thanks for your questions about putting glue on pruning cuts. There is no reason to seal the cuts. Plants have the ability to “wall off” their healthy areas on their own. In some circumstances, putting additives onto a cut may do more damage than good. Of course, knowing how to prune properly/making cuts in the right places also helps the plant help itself in the recovery process. Good luck!
I have some new 5-6′ rhodies in my yard that were “rescued” from a building site. They were growing against a building, and all have one side that is flat and a “front” that is beautiful. I would like to encourage them to fill out on the flat side without taking much (if anything) off the full side. Is there a way to encourage that, maybe by selectively prune to encourage lower buds to develop without taking off upper branches?
Julie,
Good question. If you put the plant in a new location with the old building-side/flat-side exposed to light and with room to spread out, the plant should begin to open buds and begin to expand that way. Cutting the side that was already full of life shouldn’t make the other side flush out. Patience is key here. But, removing old, dead material should also help expose more dormant buds that will fill out the blank portions. You may not see a big flush of new growth this season since we’re almost to July, but you should see some. Good luck & good on you for rescuing construction zone plants!
Hi, I like the tips for pruning but I would like to say that if you have a grafted rhododendron and cut it to the ground you will soon have a smaller purple flowering shrub next time it blooms. Same with grafted roses. My neighbor inherited a house with a superb collection of tree roses and cut them all to the ground and then wondered why all the same rose was planted!
Thanks for sharing Tanya. We don’t generally see grafted rhododendrons the way we see grafted roses (as you describe) and grafted fruit trees, both of which are much more common. Where are you finding grafted rhododendrons? We’re curious!
We recently bought a house and inherited old rhododendrons that had been overly-pruned into square/rectangle shapes. What is the best way to prune them to go back to a more natural shape? Thanks!
Corinna, Site unseen it’s difficult to give specific recommendations. That being said, you might begin by taking out all of the dead material first. Once that’s done you may be able to begin seeing where the natural form really exists. Then, take out crossing, rubbing and inward-facing branches. That may be all you’re able to do in the first year without overly pruning. The next step would be to begin correcting the shape by removing some of the reactive growth shoots that have occurred in response to what sounds like shearing. Exactly how and where to make those cuts may be answered in this article. If you’re still stumped, you may want to bring in a local gardening consultant to help or a professional fine pruner to do the work to begin re-shaping the rhodies. Keep in mind, this may be a multi-year project. Good luck!
Thank you, earned ally but willI remember when about to cut off a long leggy limb ?
Phillip, Thanks for writing in. Unfortunately, it looks like auto correct may have gotten in the way of what you had to say. If you’d like to reword your comment, we’d be happy to answer a question.
I have a war dance rhodora that was very stressed when the landscaper transplanted it due to both the transplant and then an irrigation problem where it didn’t receive water for a couple weeks in spring. The leaves rolled up and went brown and dry and the buds never opened. I replanted it with compost, better soil, gave it a big root soak, and mulched it. Now it appears to be much happier (the leaves are greener, flatter/hydrated, and don’t droop anymore) but I don’t know what to do with the buds that didn’t open. Do I just leave them there? Does it need any pruning after not blooming?
Faith, if there are dead portions, those can likely be pruned out. But, if the buds are simply dormant, they may be on hold to open at a later date. Site unseen, it’s tough to speak to your specific issue. But, I’m glad to hear that you were able to help your rhodie bounce back after a rough ride. They’re resilient plants!
I’ve got a question about what to do about buds that never bloomed and have turned brown, dried out. Should I remove them?
Deena,
Sometimes buds just don’t make it. But, sometimes there may be a bigger issue at play. If the overall plant is struggling, you may want to diagnose the larger issue and address that. But, if just a few buds failed and the rest of the plant seems fine, you can probably just snap out those brown buds. Or not. As with deadheading, removing those buds is an aesthetic choice. If the plant is healthy, it’ll drop them on its own anyway. If they’re brown because the whole plant is sick, removing a failed bud won’t bring back the whole plant. Good luck!
My neighbor has a beautiful plant and she told me I could take a “piece” of it and plant myself one! How would I go about doing that with this type of plant?
Carla, Taking cuttings to root and grow a new plant can be a great way to grow. But, how and when you do it can vary a lot from plant to plant. And, with some plants it’s as easy as taking a cutting and jamming the cutting in the earth. With others, it may be more complicated. Too, where you cut the plant is important. So, unfortunately, this isn’t a question that we feel comfortable trying to answer in a simple blog post comment. If you have specific questions and want to learn more, get in touch to set up a consultation where we can try to help you through your specific issue step-by-step.
Or, ask your friend. If she knows about doing cuttings, she might be able to help you too. Good luck!
How do we keep or prevent our rhododendron from getting any taller! What we have been doing is after blooming we pluck off any new growth in order to prevent it from getting any taller . However it still seems to be getting taller each season. It’s always full of blooms please advise. Thank you!