Hello fellow readers, “They’re long and leggy,” wrote Melanie of Newton, NJ. She and her husband acquired a lake-side fixer-upper built over a half-century ago. The rhododendrons have grown taller than the house, and branches are resting on the roof. Fortunately, you can readily rejuvenate prune rhododendron.
Indeed it’s time to rejuvenate prune, but Melanie should wait until her rhododendron is dormant in winter; I prefer early March. But early fall is an excellent time to cut back any branches that are overhanging or touching the roof; before ice and snow are added to the mix and inhibit critters’ easy access to hunker down.
How to rejuvenate prune rhododendron
The technique of rejuvenation pruning removes most of the branches and restores shrubs that have become leggy or overgrown. The good news is most rhododendron species and hybrids can be severely pruned and grow back as good as new.
One way to rejuvenate prune is to cut back each primary branch of the plant’s framework. Rhododendrons usually have three or more main branches rising from the plant’s crown that forms the framework. Cut each stem at a different height to help the shrub look natural when the new shoots mature.
Another way to rejuvenate your long and leggy is to cut the entire plant to six inches above the ground. Not all rhododendrons can survive this dramatic haircut, though. If the plant is weakened by disease or poor nutrition, it may not recover from the stresses of hard pruning.
How to determine if your rhododendron can handle rejuvenation pruning
One way to check is to cut only one of the main branches back to six inches. Then cut the other main branches to a height you are sure is healthy, say two feet. If new growth emerges from the six-inch cut, you can cut back the rest of the shrub the following year and be confident it will grow back.
Rejuvenation pruning works particularly well on rhododendrons because of a unique trait. They have tiny pink pinhead dots called latent buds that pepper the surface of older branches. These latent buds will sprout the new framework of branches. Prune above a cluster of latent buds rather than above just one bud to encourage multiple stems. Not to worry if you make a mistake, as Rhododendrons are very forgiving. Rejuvenation rocks!
Column updated 2/4/22
Link to a related story you’ll enjoy about Native Rhododendrons