Pruning Rhododendrons, however, requires some knowledge. Not all Rhododendrons are suitable to undergo heavy pruning.
Pay special attention not to prune too deeply. This can damage the Rhododendron. Preferably, leaves should always remain on the stem. The standard lilac, purple and white varieties can easily be pruned or cut back completely. Hybrids with all conceivable colours, however, cannot and should not be pruned rigorously.
Different types of pruning for Rhododendrons
There are different ways to prune Rhododendrons. From topiary to rejuvenation pruning and from light pruning to the rigorous shortening of Rhododendrons. Each pruning method has its own purpose and approach. We will go through the different pruning methods with you one by one.
First-year pruning
Remove dead flowers
Do you have a new Rhododendron in your garden? Remove the flowers after the Rhododendron has flowered for the first time. The Rhododendron will then put all its energy into forming new shoots. The flowers are removed by grasping the flower between your thumb and forefinger. Then carefully break the flower from the Rhododendron. After the first year it is no longer necessary to remove the flowers.
Topiary
the Rhododendron in the desired model
The Rhododendron grows naturally in height and width. With topiary you remove one or more branches from the Rhododendron in order to influence its shape. Think for example of branches which stick out strangely or which cross. It is also possible to prune the Rhododendron into a specific shape. For example, it is possible to create a Rhododendron cloud. Or perhaps you want to create a relatively high and narrow Rhododendron hedge. For this, you use shape pruning.
Rejuvenation pruning
for full growth
Rejuvenation pruning involves cutting back several branches to about 50 centimetres above the ground. You also remove old or dead branches from the Rhododendron. This type of pruning makes the Rhododendron look fuller and more compact. This type of pruning is often applied when the Rhododendron has bare spots or is becoming bald at the bottom. When pruning for rejuvenation, cut back to just above the last young shoot or bud. The Rhododendron will then start to sprout again from this point.
Light pruning
keeps the Rhododendron in check
Rhododendrons grow relatively slowly. Nevertheless, most species grow at least 10 to 20 centimetres per year. Is the Rhododendron planted in a border or in another place with limited growth space? Then you can prune back the Rhododendron slightly every year. In doing so, you should remove about 10 to 20 centimetres from each branch. This way you make sure that the Rhododendron stays in the right proportion to the other plants in your garden.
Rigorous pruning
for very large Rhododendrons
Has a Rhododendron become too big? Then you can prune it back rigorously, to about one metre above the ground. Leave the branches in the shape of antlers. Do not cut back the Rhododendron all the way to the ground. After a rigorous pruning, the Rhododendron will look a little less beautiful for a while, but after about 4 to 6 weeks the pruned branches will start forming leaves again.
When is it best to prune the Rhododendron?
The best time to prune a Rhododendron is right after the flowering period. After flowering, the Rhododendron starts to produce new shoots. By pruning before the shoots are formed, no valuable energy is lost. The flowering period of a Rhododendron differs per species. Most and the most popular Rhododendrons flower in spring. These Rhododendrons should therefore be pruned in April or May. Do you want to prune a Rhododendron rigorously? Then it is best to do this in December or January. This is when the Rhododendron is at rest. After cutting back the Rhododendron, the plant will have enough time to develop its sleeping eyes.
How to prune Rhododendrons?
Pruning Rhododendrons is not difficult. For relatively small Rhododendrons you can use an ordinary pair of secateurs. For larger Rhododendrons with thicker branches, it is best to use loppers or a lopper. Make sure that the loppers or lopper are sharp and that the blade is not rusty. If you cut with blunt or rusty tools, you run the risk that mould or rot will get hold of your Rhododendron. In the worst case, the Rhododendron might even die completely.
Which Rhododendrons are easy to prune?
Not all Rhododendrons are easy to prune. Species such as the Rhododendron Taurus, for example, have few dormant eyes. Crossed Rhododendrons are also difficult to prune. Do you want to be sure that your Rhododendrons can be pruned easily? Then choose one of the following Rhododendron species.
- Rhododendron Ponticum
- Rhododendron Ponticum roseum
- Rhododendron Catawbiense
- Rhododendron Roseum Elegans
- Rhododendron Cunninghams White
- Rhododendron Jacksonii
- Rhododendron English Roseum
- Lee's Dark Purple Rhododendron
- Rhododendron Nova Zembla
- Rhododendron Cunninghams White
Small Rhododendrons that you do not need to prune
Are you placing a Rhododendron in a small border or do you want to put it in a pot? Then it is best to choose a dwarf Rhododendron. These Rhododendrons stay small. In principle, you do not need to prune them. Rhododendron Centre De Valouwe has a large range of dwarf Rhododendrons. We can also put together a varied border bouquet with small Rhododendrons that flower at different times. Are you interested?
Maintenance after pruning the Rhododendron
The Rhododendron is a strong plant. Therefore, it is not necessary to maintain the Rhododendron after pruning. There is no need to fertilise the Rhododendron. In hot, dry periods it is advisable to water the Rhododendrons more after they have been pruned. Always do this from below, preferably with a drip hose. This way, there is no risk of the leaves going mouldy.
Online advice on pruning Rhododendrons
Do you want to know more about pruning Rhododendrons? Or do you or your gardener have specific questions about pruning a Rhododendron in your garden? Then feel free to contact one of the Rhododendron specialists at Rhododendroncentrum De Valouwe. We will be happy to share our knowledge about pruning Rhododendrons without any obligation. We can also assist your gardener in pruning, for example by video calling.
