Rhododendrons are grown for their springtime flowers - exuberant, colourful blooms set against glossy, evergreen leaves. While there’s no need to prune rhododendrons, you may want to keep their overall size in check or rejuvenate a neglected specimen. While you’re busy with the secateurs, a little deadheading will keep your shrub looking great too.
The simplest form of pruning is deadheading, which encourages the plant to put its energy into new growth rather than producing seed. As soon as the shrub has finished flowering in spring you can remove the spent flowers, cutting just above a set of leaves. This is also a good time to remove dead, dying or diseased branches.
If your rhododendron needs to be significantly reduced in size using a saw, this should be done over winter when the plant is dormant, between January and March. You may sacrifice a few flowers in the spring, but it gives the plant a whole season to regrow.
Light pruning and deadheading should be tackled with a sharp pair of secateurs, while gently reducing the size and shape of your rhododendron may be easier with long-handled loppers. Shortening the branches down to a cluster of leaves once the shrub has finished flowering will keep it from getting too big and encourage bushier growth.
Should you have an old, established rhododendron that needs to be given a new lease of life, heavy pruning is possible. Choose a frost-free day in February or March and cut back branches hard to one of the tiny, dormant 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 may be better to spread the work over a few seasons, reducing the size of the shrub by a third each year until you reach the desired size and shape.
Always feed, mulch and water the plant well after heavy pruning.
Learn how to properly care for your evergreens by heading over to our evergreen plants hub page - T&M's ultimate evergreen plants resource.
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