The rhododendron is one of the star plants in the garden. It adorns both English and Japanese-style gardens with its abundant blooms. Pruning this elegant shrub is not very complicated.
When to prune the rhododendron?
The time of pruning depends on the flowering period and therefore on the variety of the rhododendron. Let's not forget that the genus is divided into nearly 900 species for a multitude of varieties. For example, Rhododendron arboretum is a real tree that can reach 12 m in height, while Rhododendron camtschaticum has a creeping, spreading habit that does not exceed 30 cm in height. Between these two extremes, there is a whole range of shrubs more common in gardens.
Generally speaking, training pruning is done in early spring and maintenance pruning just after flowering.
How do I prune a rhododendron?
Training pruning
At the beginning of its life, the rhododendron needs a training pruning which will allow it to expand its silhouette more quickly. With the nails of your thumb and forefinger, pinch off new growth just above a leaf in spring. New stems should appear at this cut. Wait until they reach 5 cm in length before pinching the tips of these shoots again.
Maintenance pruning
On older plants, wait until the shrub has flowered to consider maintenance pruning. Take a small pruning shears whose blades will have been disinfected with methylated spirits to avoid the propagation of diseases from one plant to another.
Then cut each wilted flower just under its stalk. The pruning must be precise in order not to cut the stems carrying at their ends the latent buds which will ensure the blooming of the following year.
Always with the secateurs, cut the dead stems at their bases. Also remove the branches that cross in the center of the shrub, or those that seem damaged or diseased.
Specific case of tree rhododendron
Prune all the low branches in autumn when the young tree is formed to keep only 6 to 8 carpenter branches. Wait two years before pruning all branches less than 2 cm in diameter. Cut the shoots and all the stems present under the framework to form the main trunk.
If it is an old tree that has never been maintained, don't hesitate to cut it back drastically in the fall or winter, except during the frost period. To do this, take a saw or a lopper and cut all the branches at 20 cm above the frame.
