Tap to Read ➤

Your Guide to Pruning a Rhododendron Plant

Pallavi M Nov 26, 2018
Pruning a rhododendron helps control the size and shape of the plant. It also promotes healthy growth by removing dead or diseased leaves and branches.
Cutting or removing diseased or unwanted parts enhances shape and flowering potential of plant. It is very common to remove broken branches; enhance the plant's shape by cutting unwanted branches, and increase light penetration and air circulation by thinning them.
However, there are quite a few differences relating to pruning a tree, shrub, or a hedge. Pruning roses is very different from pruning a rhododendron plant.

The Rhododendron Plant

The rhododendron genus has over 1,000 species of flowering plants, which also includes azaleas. These plants have fibrous roots, and they grow well in acidic soil having pH levels of 4.5 to 5.5. However, some species also grow as epiphytes.
They can be evergreen or deciduous, found in Northern Hemisphere and parts of Southern Hemisphere, including Southeast Asia and Northern Australasia. These can be recognised by shrubs and small trees. The flowers are in clusters of red, pink, white, yellow, mauve.
The catawba rhododendron, or mountain rosebay, is an evergreen shrub that has dark-green leaves and red, white, or lavender flowers. P.J.M. rhododendrons, producing lavender-pink or white blooms, are the most adaptable and the easiest to grow.
The flowers of this plant bloom in the month of April. The size, structure, and the glorious blooms make rhododendrons and azaleas top favorite ornamental plants for landscaping.
If you want to improve the appearance of your rhododendron plant, prune it in any shape you want by removing the dead or decaying branches. Pruning also promotes a denser growth of the foliage. However, certain precautions have to be followed while doing this.

When to Prune

The most favorable time to prune the plant is during spring, after its blooming period. It is advisable not to prune the rhododendron in late summer or fall, because it can make the plant susceptible to winter injury.

How to Prune

You need sharp scissors or pruning shears, lopping shears, and gloves. Rub alcohol on pruning shears to disinfect them. Knowing the species of the rhododendron plant will help you decide the type of pruning needed. Rhododendrons are pruned mainly for three reasons.

Pruning for Shape Enhancement

Pruning rhododendrons enhances its look. Pruning at the plant base leads dense foliage growth. It controls height and width of the plant. Pruning a large rhododendron may need a different method.
Shaping a broad-leaved plant is easier because it has longer internodes than the short-leaved ones. Snipping the stems an inch above a leaf or a node encourages a denser and more compact growth the following spring.

Pruning for Maintenance

Maintenance pruning is very easy and should be done every year to remove dead or diseased branches and spent flower clusters. Light pruning does not affect flowering of plant, if done carefully.
You can remove a diseased stem with a pruning shear, cutting just below the part that is affected. Snip off old flower clusters by cutting just above the new growths. You should remove the dead flowers from the plant in order to encourage new growth.
However, do not snap the clusters with your fingers, as it may impact the new buds. Broad-leaved rhododendrons and azaleas benefit a lot from maintenance pruning.

Pruning for Rejuvenation

Rejuvenation pruning is best done in the winter months, when the plant is in a dormant stage. By pruning large number of branches, you can restore a plant which has become unattractive. This will lead to a vigorous growth the next season.
However, it is better to prune above a cluster of three or four buds, because it promotes the growth of multiple branches. Rejuvenation pruning can be done by cutting three or four branches at alternating levels, it produces a distributed growth when the shoots mature.
A heavier pruning is required if your rhododendron is diseased. Cut one of the main branches back to 6 or 8 inches. If you observe new growth from the cut, you can safely prune the remaining branches the following year.
Pruning helps maintain an attractive and compact shape. It also protects the plant from various diseases. In addition, you can mulch the rhododendron with a layer of pine needles and peat moss, which will ensure healthy growth.