So you planted a rhododendron years ago when it was just a small shrub, and now it’s grown into a massive beast that is taking over your yard This is a common problem gardeners face with rhododendrons and other large shrubs The good news is there are several effective solutions for managing overgrown rhododendrons.
Why Rhododendrons Get So Big
Rhododendrons are woody shrubs that can grow quite large over time, often reaching 8-15 feet tall and wide at maturity. There are over 1,000 species of rhododendrons and azaleas, and while some stay more compact, most become quite substantial in size.
Here are a few key reasons rhododendrons grow so large:
-
Long lifespan: Rhododendrons are very long-lived plants that can thrive for 40-80 years or more. With decades to grow, they keep getting bigger each year.
-
Rapid growth rate Rhododendrons grow relatively quickly, averaging 13-24 inches of new growth per year. All that new growth adds up over time
-
Lack of pruning: Rhododendrons naturally form dense, rounded shapes, but without pruning they can become unruly and overgrown.
-
Ideal growing conditions: Rhododendrons thrive in moist, acidic, organic soil and shady locations. When happy, they put energy into rapid growth.
So in the right conditions and with minimal maintenance, rhododendrons readily grow into jumbo-sized shrubs.
Problems Caused by Overgrown Rhododendrons
A too-large rhododendron causes several issues:
-
Blocked views and light: Massive rhododendrons block views and darken rooms by covering windows.
-
Crowding: Dense, spreading rhododendrons crowd out other plants and take over planting beds.
-
Damage to structures: Weighty, overhanging branches can damage gutters, roofs, and siding.
-
Difficult maintenance: Big rhododendrons are hard to prune, dig up, or control. Dead leaves and debris get trapped inside.
-
Messy look: Without pruning, large rhododendrons often look raggedy, overgrown, or poorly maintained.
The bottom line is an oversized rhododendron simply won’t fit nicely in your landscape anymore. It requires intervention to reduce its size and keep its growth in check.
5 Options for Managing Large Rhododendrons
If your rhododendron has outgrown its space, you have five main options:
- Aggressive pruning
- Minor routine pruning
- Transplanting
- Turning it into a tree
- Removing it
Let’s explore each of these solutions in detail:
1. Aggressive Pruning
You can prune back overgrown rhododendrons to reduce their size. This involves cutting back major branches and stems right down to the main trunk.
When to prune: For best results, prune right after flowering in spring. Rhododendrons only flower on old wood, so pruning later in the season removes next year’s flower buds.
How much to prune: Removing 30-50% of the plant’s height and width can help reign in an overgrown rhody. Focus on thinning inner branches first.
Drawbacks: Dramatic pruning stresses the plant and leaves it looking chopped and unattractive while it recovers. It takes years to regain its natural form.
Aggressive pruning is best for quick size reduction of badly overgrown rhododendrons. But it must be followed up with maintenance pruning to keep the plant contained.
2. Minor Routine Pruning
For rhododendrons that are just slightly too large, regular minor pruning each year can help contain their growth.
When to prune: Prune right after flowering, removing no more than 1/3 of the plant’s branches.
What to prune: Selectively prune branches that extend beyond the plant’s desired boundaries. Avoid shearing the whole plant, which promotes dense regrowth.
Benefits: Minor annual pruning improves the plant’s shape and keeps it tidier without drastic size reduction. It’s less stressful for the plant than major chopping.
Regular light pruning is ideal for maintaining rhododendrons at a desired size before they get severely overgrown. It’s a gradual, gentler approach.
3. Transplanting
For a rhododendron that’s healthy but just in the wrong spot, transplanting it to a new location is a great option.
When to transplant: Transplant in early spring before bud break or in fall after leaves drop. Avoid periods of active growth.
How to transplant: Prepare a wide hole in advance. Carefully dig up the rhododendron keeping roots intact. Replant at same depth, water well, and mulch.
Benefits: Transplanting removes the rhododendron from a problem area and gives it a fresh start in an environment where it has room to thrive.
Transplanting is very effective but requires heavy labor. It’s easiest when plants are young. Mature rhododendrons with substantial root balls can be difficult to relocate.
4. Turning Into a Tree
You can prune back the lower branches of a large rhododendron to raise the canopy and give it the look of a small tree.
When to prune: Limb up rhododendrons in early to mid-summer after flowering is finished.
How to limb up: Remove lower branches in stages over a 2-3 year period. Never remove more than 1/3 branches in one year.
Benefits: Limbed up rhododendrons have attractive tree-like forms. You can plant shade-loving plants beneath the raised canopy.
Arborizing overgrown rhododendrons opens up the landscape below. It brings light and air circulation into previously dense, shaded areas.
5. Removing the Rhododendron
In some cases, the best solution is to remove the rhododendron completely if it is overly large and cannot be salvaged.
When to remove: Any time of year works, but removal is easiest when the ground is moist, like early spring.
How to remove: Cut the rhododendron down to a stump. Dig up as much of the root system as possible. These are very tenacious plants so roots left behind may re-sprout.
Benefits: Removing opens up space for new, better-suited plants. It instantly eliminates problems related to rhododendron overgrowth.
Total removal is simplest and provides a fresh start. But it can be hard work to fully extract such a substantial shrub. You lose the plant’s beauty and have to replace it.
Key Tips for Managing Large Rhododendrons
Here are some important tips to help you get overgrown rhododendrons under control:
-
Start pruning and containment efforts sooner rather than later before plants get unruly.
-
Always prune rhododendrons right after flowering to avoid removing next year’s flower buds.
-
Never remove more than 1/3 of the plant when pruning to avoid shock and dieback.
-
Disinfect pruning tools before each cut to prevent spread of disease.
-
Consider removal if the rhododendron is no longer suited to its location or taking up too much space.
-
Transplant in early spring or fall and take steps to avoid transplant shock like watering deeply.
-
Limb up rhododendrons gradually over a few years for best results and tree-like forms.
-
Monitor closely for resprouting if you remove a rhododendron entirely and dig up roots.
-
Fertilize and water rhododendrons periodically to keep them healthy, but avoid overfeeding.
With some patience and persistence, you can get that giant rhododendron back under control. It simply needs thoughtful pruning, care, or relocation to right-size it for your landscape.
Frequently Asked Questions about Overgrown Rhododendrons
Here are answers to some common questions about managing too-large rhododendrons:
How long does it take a rhododendron to recover from severe pruning?
It can take 2-3 years for a rhododendron to regain its natural shape and beauty after aggressive pruning. Light pruning has less impact on appearance.
Can I cut back a 10-foot tall rhododendron to 3 feet?
Yes, you can prune a rhododendron this drastically, though it will look very unattractive as it re-grows over the next few years. It’s better to prune gradually over time.
Should I prune my rhododendron before or after it flowers?
Always prune right after flowering. Rhododendrons set next year’s flower buds in summer/fall so pruning later removes new buds.
Is it better to transplant or prune an overgrown rhododendron?
Transplanting is preferable if the plant is healthy but just in the wrong spot. Pruning is better for rhodies you want to keep but are just too big where planted.
How can I stop my rhododendron from getting so big?
Regular light pruning each year (removing no more than 1/3 branches) will contain size. Avoid high-nitrogen fertilizer which spurs growth.
What is the best way to get rid of a large unwanted rhododendron?
Cut it to a stump and dig up as much of the root system as possible. Monitor for resprouting from remaining roots. Stump removal is another (costlier) option.
Can I limb up a 15-foot tall rhododendron into a tree form?
Yes, rhododendrons can be limbed up over time to create the look of a small ornamental tree. Remove lower branches gradually over 2-3 years.
Is it better to cut back or remove a rhododendron near my house?
Removing it entirely is better if it’s blocking views/light significantly. Pruning can work if it just needs mild size reduction to fit the space better.
How much does it cost to have a large rhododendron removed?
On average, $300-800 for a landscape company to remove a full-size rhododendron depending on size. DIY removal costs much less.
Conclusion
Managing an overgrown rhododendron comes down to either pruning it to reduce its size, transplanting it somewhere with ample room, or removing it altogether if other options fail. With the right technique and timing, you can get your massive rhody under control and restore balance to your landscape. The key is acting sooner than later before it gets completely out of hand!
Fine Gardening Project Guides
I learned to prune rhododendrons by destroying my prized rock garden. I had a 30-foot-tall pine that I needed to cut down. It missed the house by a wide margin, but it didn’t miss the rock garden, which I had lovingly tended for years.
When the last of the pine tree was removed, I discovered that the damage was surprisingly slight, except for a beautiful Rhododendron ‘Roseum Elegans’, now a 2-foot mound of broken branches and torn foliage. Curious to see if the shrub would recover on its own, I trimmed it back a bit, cut back the scaffold of branches to as pleasing a shape as possible, and waited to see what would happen. Four years later, the rhododendron is one of the most eye-catching shrubs in the yard, with a beautiful shape, dense branches, and plentiful flowers. The incident illustrates how responsive rhododendrons can be to even severe pruning.
There are three common reasons for pruning rhododendrons—maintenance, shaping, and rejuvenation—and the pruning method for each is easy to learn. The result is a shrub with dense branching, plentiful foliage, and abundant flowers. And you don’t have to drop a pine tree on your shrub border to learn how to do it.
Method 1: Maintenance pruning removes old flowers and dead wood
Snip at the base of the old flower trusses to keep the plant’s energy focused on producing growth rather than seed. Also, remove dead or diseased parts of the shrub—follow the branch back to healthy wood and make a cut there.
Maintenance pruning consists of the removal of spent flower clusters, called trusses, and also of any dead or diseased wood. The trusses are not only unsightly but will eventually form seed, which uses precious energy that would otherwise be available to the plant for vegetative growth. Maintenance pruning is the easiest type of pruning and is the only one that needs to be done every year.
To remove old flower trusses on rhododendrons, use a pruning shear to snip the truss at its base, about ½ inch above the emerging flush of new growth. Some folks just grasp the stem with their thumb and forefinger and snap the truss from the plant. This works well most of the time, but occasionally the truss breaks off, taking some of the new growth with it. By using a pruning shear, such accidents are avoided.
| Maintain your rhododendron by snipping off spent flower clusters (trusses) . . . |
| . . . and by removing dead and diseased wood. |
Wood damaged by storms or a harsh winter should be clipped from the plant. Diseased stems, often identified by their wilted, curled yellow-green leaves, should also be removed. Make the cut below the damaged portion of the plant, taking care to cut into healthy wood right above a dormant bud. Be sure to disinfect the shears with rubbing alcohol between cuts.
Maintenance pruning is best done when the flowers have faded and before the flush of new growth rising beneath each truss is more than an inch or so tall. Many types of rhododendrons can benefit from maintenance pruning, including some deciduous azaleas, like the Knap Hill-Exbury hybrids, and most broad-leaved evergreens, such as the popular hybrids of mountain rosebay (R. catawbiense). Some varieties of rhododendron, most notably small-leaved cultivars like ‘Elite’, ‘Northern Starburst’, and ‘PJM Regal’, rarely set seed and do not require maintenance pruning. If your flowers and flower stalks simply shrivel up and essentially disappear in the weeks after flowering, then your variety doesn’t set seed and doesn’t need to be deadheaded.