Nothing brings a spectacular show of spring color like rhododendron bushes. Although they’re pretty hardy, rhododendrons will need a little investment of time to keep their flowers flourishing. In this article, we’ll explain how to trim rhododendron bushes to keep them looking stunning for the whole spring.

What are rhododendron bushes?

Rhododendrons (Rhododendron ferrugineum) are deciduous or evergreen shrubs that grow mainly in parts of Asia and North America. These beautiful bushes favor woodland regions and there are over a thousand rhododendron varieties. Rhododendrons have vibrant green foliage, woody stems, and incredible flowers that burst into clusters of color in spring. Because of these intense displays, they are popular with gardeners.

Why trim rhododendron bushes?

These elaborate evergreens are hardy plants that can grow quite happily without pruning. But to keep their displays as gorgeous as possible gardeners will often deadhead any drooping flowers along with trimming out any dead growth. To stimulate abundant growth for subsequent seasons, many types of rhododendron can occasionally tolerate a harsh trimming without ill effects. Rhododendrons can sometimes become too big for the garden, so trimming is useful to keep them at a manageable size.

When to prune rhododendron bushes

Rhododendrons will start to flower in the spring and continue through into the early summer. Within this season, you can freely deadhead any wilting flowers to help keep the bush looking beautiful. Dead stems can be pruned once the rhododendron has finished flowering for the year. As for more aggressive sessions of cutting back, this is best done between February or March before the new growing season gets underway. Any drastic measures concerning massively overgrown rhododendrons should occur in the late winter when the shrub is dormant.

Tools for pruning rhododendron bushes

When pruning rhododendron bushes, there are a few basic tools that you need to keep on hand for the job:

• Secateurs – A good quality pair of secateurs can handle most aspects of rhododendron trimming such as deadheading.
• Lopping shears – The long reach and heavy clippers on lopping shears are perfect for pruning more stubborn rhododendron stems.
• Pruning saw – If rhododendrons get too big for a garden, a pruning saw can be used to trim the shrub down to a manageable size.

How to trim rhododendron bushes

Although rhododendrons are hardy shrubs, they can still be pruned incorrectly. This can cause great harm to the plant. Here’s how to trim rhododendron bushes properly:

1. For deadheading, simply snip off any drooping flower stalks just below the first couple of leaves.
2. Once flowering has finished, cut away the spent flower stems. When removing any diseased growth, cut right back to a healthy area of the stem.
3. When it’s time to thin out the shrub for next year, decide how far back you want to cut to give the inner branches some space. Then, choose the set of leaves closest to that point and snip the stem about a quarter of an inch above those leaves. Don’t cut off more than 15 to 20 inches of a stem.
4. For any hard cutting back, cut each stem right down to just above areas with small buds – these will form the basis of the new growth and should be left alone. You can reduce the size of the rhododendron shrub down to about 12 to 15 inches high if needs be. Prune the thicker central branches at various heights.
5. When you need to do some really drastic pruning, you can cut as low down as six inches. Just remember to leave some buds present. In these circumstances, the plant might not flower for a couple of years as it recovers.

What not to do when pruning rhododendron bushes

The most important thing to avoid when pruning rhododendrons is to not get too enthusiastic during trimming. Most of your pruning should consist of cutting off any spent flowers once they’ve finished for the season. Only engage in more drastic pruning if the rhododendron actually needs it. This could be because the shrub has simply grown too large and unwieldy, but if it isn’t at this stage it should just be lightly pruned.