Pruning your rhododendron is a good way to keep it from getting too big or to bring an old plant back to life. While youre busy with the secateurs, a little deadheading will keep your shrub looking great too. Horticulture expert Mandy Bradshaw shows you how to prune your rhododendron so that you can get the most out of its spring flowers.
Rhododendrons are beautiful spring-blooming shrubs that add a pop of color to the garden. However, they can easily get out of control and become too large for their space. If your rhododendron has gotten too big, don’t panic – there are solutions. Here are some tips for dealing with an overgrown rhododendron:
Evaluate the Situation
Take a step back and objectively look at the rhododendron Consider the following
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How big is it currently? Measure the height and width.
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How big was it supposed to get? Check the plant tag or research the variety online to find its expected mature size.
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How much space do you have for it? Take measurements of the area to determine if the rhododendron has outgrown its allotted space.
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Does it get enough sun? Rhododendrons need at least 6 hours of direct sun daily. Lack of light can cause leggy growth.
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Are the roots exposed? This is a sign it may be pot-bound or root-bound and needs more space.
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Are there dead branches? Thinning and woody growth can be signs of an overgrown shrub.
Prune Selectively
The best time to prune rhododendrons is right after flowering. Remove dead or damaged branches first. Then make strategic cuts to shape the plant and encourage bushy new growth:
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Thin inner branches and branches that rub or cross to improve air circulation.
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Shorten long, leggy branches, cutting back to just above a leaf node.
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Remove suckers and inward facing branches to keep an open, rounded form.
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Cut tall outer branches back by 1/3 to 1/2 their length to reduce height.
Only prune up to 1/3 of the plant each year to avoid shock. Disinfect pruning tools between cuts.
Consider Transplanting
If pruning alone won’t solve the problem, transplanting the rhododendron to a new location may be necessary. This is best done in early spring or fall. Carefully dig up the root ball and replant in an area with well-draining soil and ample room. Water well after transplanting and mulch around the root zone. Transplant shock may cause it to not bloom for a season, but this is normal.
Provide Proper Care
Good care is key to preventing rhododendrons from becoming overgrown:
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Water 1-2 inches per week, adjusting for rainfall. Avoid wet feet.
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Fertilize in early spring and mid-summer with acid-loving plant food.
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Mulch around the root zone to retain moisture and suppress weeds.
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Remove spent flowers and seed pods to promote reblooming.
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Prune each year right after flowering by selectively removing unhealthy and overcrowded branches.
Consider Dwarf Varieties
When planting a new rhododendron, select a dwarf cultivar suitable for your space. Smaller varieties like R. ‘Ramapo’, R. ‘April Rose’, and R. ‘Cunningham’s White’ typically grow to just 3-5 feet tall and wide at maturity. Buying the right size plant can prevent headaches down the road.
With some patience and proper care, an overgrown rhododendron can be tamed. The key is to avoid trying to fix it all at once. Make small, gradual changes over time to keep this beauty in bounds.
How to prune a rhododendron
Hard prune overgrown shrubs in winter while the plant is dormant : Rhododendron Wine and Roses from T&M
With a sharp pair of secateurs, you can do light pruning and deadheading. Long-handled loppers may be easier for gradually reducing the size and shape of your rhododendron. Once the flowers are gone, cut the branches back to a cluster of leaves to keep the bush from getting too big and encourage bushier growth.
Heavy pruning is an option for an old, well-established rhododendron that needs a new lease on life. On a day in February or March when there won’t be any frost, cut back branches all the way to one of the small, silent buds.
If necessary, you can coppice the plant down to around 150cm tall. Proceed with caution though, as not all rhododendrons will respond well to this treatment. It might be easier to do the work over a few years, cutting the shrub down by a third each year until it’s the right size and shape.
Always feed, mulch and water the plant well after heavy pruning.
Visit our comprehensive hub page for more info and expert advice on evergreen plants.
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What Not to Do to Your Rhododendrons
FAQ
How to reduce the size of a rhododendron?
How to trim an overgrown rhododendron?
How to remove large rhododendron?
How big can a rhododendron bush get?
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Common Name
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Rhododendron
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Plant Type
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Shrub
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Mature Size
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2-20 ft. tall, 3-15 ft. wide
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Sun Exposure
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Partial
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Soil Type
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Moist, well-drained
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