The rhododendron is one of the most striking shrubs with beautiful flowers and lush foliage. For popular shrubs in many landscapes, the question of how to prune a rhododendron is a frequently asked question. Although rhododendrons often require little pruning, especially in natural settings, these shrubs respond well to occasional pruning. If there is excessive growth, severe pruning may even be necessary. Pruning rhododendrons is usually for care, shaping and rejuvenation - as is the case with overgrown plants.
Best time to prune the shrub
When to cut rhododendrons? According to most professional landscapers, this is the ideal time to prune rhododendronsthe late winterwhen the plant is in the dormant phase. However, any time between the first frost in fall and the last frost in spring (as long as the sap content is low) is suitable. Immediately after the lush spring growth, when the new foliage is still hardening, is one of the worst times to prune rhododendrons. This will likely prevent flowering.
If you are considering pruning, you should prune the shrub in late fallfertilize from the previous year. Pruning later may result in limp growth. Because the buds form on next year's flowers, they are already well advanced by the time flowering stops. You should therefore not cut your rhododendron by more than 38-50 cm after it has faded. Cut the plant back to expose the inner branches. Follow the branch to the last ring of leaves you want to preserve and cut just above those leaves.
There are three common reasons for pruning rhododendrons—maintenance, topiary, and rejuvenation—and the pruning method for each of these reasons is easy to learn. The result is a shrub with dense branching, lush foliage and abundant flowers.
Method 1: Maintenance pruning removes old flowers and dead wood
Snip at the base of the old flower clusters so the plant's energy is focused on producing growth rather than seeds. Also remove dead or diseased parts of the bush - you need to follow the branch back to the healthy wood. Cut the rhododendron there. Maintenance pruning consists of removing the spent flower clusters, the so-called panicles, as well as dead or diseased wood. Not only are the panicles unsightly, but they also eventually form seeds that use up valuable energy that would otherwise be available to the plant for vegetative growth. Maintenance pruning is the simplest type of pruning and the only one you need to do every year.
To remove old flower clusters on rhododendrons,cutRemove the flower clusters at the base with secateurs, about 1.5 cm above the new shoots. Some people simply grasp the stem with their thumb and forefinger and tear the bundle from the plant. Most of the time this works well, but occasionally the container breaks off and takes some of the new growth with it. Such accidents can be avoided by using pruning shears.
Maintenance pruning is best carried out when the flowers have faded and before the new growth among the individual shoots is more than one centimeter high. Many rhododendron species can benefit from pruning. If your flowers and flower stalks simply wilt and essentially disappear in the weeks after blooming, then your variety will not set seed and does not need deadheading.
Method 2: Topiary pruning promotes the natural growth of the plant
Topiary and other formal pruning techniques are used to shape a plant into a shape that it would not naturally take. As the name suggests, topiary is all about changing the shape of the plant, and this can be done for many reasons, from encouraging denser branching to controlling plant width or height.
Topiary trimming improves the appearance of a plant by encouraging greater branching at growing points. Because many evergreen rhododendrons retain their leaves for about three years, a branch features a series of leaf whorls, each of which grows for a year. The leaf whorls are separated from each other by leafless stem sections called internodes. In general, broad-leaved rhododendrons have much longer internodes than small-leaved and deciduous types and benefit most from shaping.
Onea rhododendron in shapeTo bring it, follow the branch from the end to the last wreath of leaves you want to keep. Cut the branch about 1/2 inch above the top leaf in this clump. Repeat as needed. Topiary pruning is easiest to do in late winter when the plant is dormant. This means you sacrifice a few flower buds, but the newly sprouting shoots have a complete growing season ahead of them.
Method 3: Rejuvenation pruning requires drastic cuts to the old wood
During rejuvenation pruning, each main shoot of the plant's framework is carefully cut back.Have rhododendronsoften three or more main branches extending from the crown of the plant. These branches, the so-called main branches, form the basic structure of every shrub. Each branch is cut at a different height to create a staggered arrangement that keeps the shrub looking natural as the new shoots mature.
Rejuvenation pruning is best used for restoring shrubs that have become limp, overgrown, or otherwise unsightly. Many rhododendron species and hybrids can be cut back heavily and will then be like new again. When rejuvenating, most of the plant's branches are removed so that strong new growth emerges from the previously leafless old trunks. The new growth matures into a new framework of branches, which can then be formed into a magnificent shrub over the years. This type of pruning is best done in winter when the plant is dormant.
Also worth reading:Is your rhododendron not blooming? Find the cause!
