• Featured Gardening Articles

  • Featured Recipes

  • Article Categories

  • Get Garden Help by the Month

  • more info

How to Prune Rhododendrons

July 18, 2014

Need help learning how to prune rhododendrons & azaleas? We’ve got you covered! Fortunately, you can fine-prune these beautiful plants just about any time of year as long as you take care not to cut off all the flower buds.

2014_07_GardenMentors_Rhododendron_11

Need pruning tools? Courtesy of our friends at Fiskars, we’ll be giving away a pair of bypass pruners and a folding handsaw to one lucky reader. Read on for details…(this giveaway is now closed.)

Rhododendron in need of pruning

Before we began, this foundation evergreen rhodie was filled with dead material.

The reality is, sometimes you get to pruning when you have the time. Not every plant can be pruned successfully at the same time as every other plant, but rhodies are quite forgiving on timing.

Simple rules to follow: don’t prune them if they are flowering (unless you want to cut a few flowers for a vase) or about to flower (you’ll miss out on their best season) or if it is frozen outside (and you might break a branch along the way). And, if pruning in spring, summer or autumn, be sure to check for hornet nests. They love to build their summer homes in rhodies and other medium-sized shrubs — especially when they’re dense with dead wood! But remember: rules are made to be broken, and your garden and plants may require a bit of rule bending.

In all honestly, we knew how to prune rhododendrons, but we just hadn’t gotten to cleaning this one up in a couple of years. Trees and shrubs grow just fine without us cutting, shaping and coiffing them all the time. But, the messy interior of this rhodie was an eye-sore we could no longer ignore. So, on a day that eventually topped 90F, we spent a couple of hours beautifying this blooming beauty. We got done well before temperatures soared. No sunburns here and by far the plant is in better shape than before.

All we needed for the job: a pair of bypass pruners, a folding handsaw, and a tarp.

Rhododendron needing pruning

Before pruning, this rhodie had lots of interior dead wood. To make cleaning up all the detritus we would be cutting, we spread a sheet of plastic under the shrub before we began.
A tarp works great too.


Did you know that all azaleas are rhododendrons?
Yep, Rhododendron is actually a genus of plants into which the azaleas are also classified! So, of course it makes sense that knowing how to prune rhododendrons would set you up for success in pruning your azaleas as well. Generally speaking, azaleas are twiggier, so you’ll just be in for making a lot more small cuts than you would on bigger rhodies.

Pruned Rhododendron

After the rhodie was cleaned of dead wood, we removed rubbing branches.

Fine pruning is not shearing off the outside to “shape” a plant. Often the sign of a good pruner is you can hardly tell they’ve cut anything from your plants. Still, when we were done with interior cuts, sunlight & air could flow through the plant. This helps reduce pest and disease issues in many garden situations.

Often the sign of a good pruner is you can hardly tell they've cut anything from your plants.

After we finished pruning & deadheading this rhodie,
it almost looks as though nothing was done from this side.

Because the plant hides a foundation & utility area, we chose not to lift all the lower limbs, which would expose the ugly part of the house from a nearby patio. Eventually, we may decide to plant something under this rhodie at which time, we will limb it up. But no way was planting going to happen during a heatwave in July!

Ready to dive in but still need the right tools for the job? In the comment section for this post, tell us about the most beautiful rhodie or azalea in your garden. Is it colorful, fragrant, filled with pollinators, or what makes it a plant you’d love to get cleaned up.

One person will be chosen via random.org on Monday, July 28, 2014 to win a pair of Large Bypass Pruners and a 7″ PowerTooth Folding Handsaw to be shipped to them from our friends at Fiskars. Comment period to enter closes at midnight PDT on Sunday, July 27, 2014. (This giveaway is now closed.)

(More details on our relationship as paid writer with Fiskars at the end of this post, but to be clear we have received no compensation for this post or tool giveaway. And, learn more about using random.org at the end of this article.)

Next up: a Visual step-by-step guide to deadheading your rhododendrons.

It’s a total myth that your rhodies won’t bloom if you don’t deadhead them!

Somebody’s mother a long time ago must have lied to their kids to get them to do the deadheading dirty work for her. 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. Removing deadheads when you prune rhodies is really an aesthetic choice not a critical move to keep them flowering.

If you want to deadhead your rhodies, here’s how:

Deadheading a rhododendron.

After a rhodie has bloomed, if you wish to deadhead it, grip the old flower head between your fingers, taking care not to damage flower or leaf buds or stems surrounding the old parts.

deadheading a rhodie

Carefully, bend the flower remnant from between any new growth.
We like to do this by hand rather than with clippers.
Hint: you might want to wear gloves on rhodies that are stickier than this one.

Deadheaded rhodie

Rhodie deadheads usually snap out easily & cleanly.
If part of the deadhead remains, pinch that out as well.

And one final lesson: know your buds. When learning how to prune rhododendrons, it’s important to know a flower bud from leaf and stem growth. This way, you can quickly avoid cutting off all the flowers when you fine prune your plants. (And, if you’re hiring a maintenance team, you can quiz them about what’s what on your plant. If, for instance, they want to shear your plants into a hedge in February, odds are they’ll be cut off all your potential flowers.)

Rhododendron Flower Bud

Within a month or so of blooming, rhodies will put on new buds like this that will flower in the following spring. (Okay, sometimes they open in fall or winter, too.)

New Leaf growth on a Rhodie

Some rhodie branches will form vegetative buds that open leaves & new stems like these.

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.

Red Rhododendron Blooming

Next May or June we’ll enjoy another week or two of blood red blooms on this beautiful rhodie. Fact is: it would have bloomed whether we pruned it or not!

(Fine Print: Garden Mentors is a paid writer for Fiskars. However, we have received no compensation for this post. The winner of the Fiskars tools will be selected by random.org. First to comment is number one and subsequent comments will be counted sequentially. Contact information will be provided to Fiskars, which will ship the tools to the winner. This giveaway is now closed. )

9 Comments

  1. […] In the meantime, get outside and prune your rhodies; her nest happens to be in the rhodie we used to illustrate our post on how and when to properly prune and deadhead a rhododendron. […]

  2. […] Sure, a mushroom might do you in quickly (or slowly, which may be worse), but a dog snapping a rhodie twig in half probably won’t ingest nearly enough to make Fido croak. More likely, Spot will […]

  3. David Head says:

    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?

  4. 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!

  5. David Walters says:

    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

  6. David Walters says:

    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

  7. 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!

  8. Julie says:

    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?

  9. 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!

Leave a Reply

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

(You can support this blog by buying through our links. Purchases made through the affiliate links on this page and others on this site pay a small percentage to Garden Mentors but don’t cost you anything extra. Thank you for buying and helping support us!)