Three pruning actions on rhododendrons
There are three pruning actions associated with rhododendrons. One is the removal of spent flowers (trusses) and any diseased or dead wood. Most rhodos produce seeds and you can get your rhodo to concentrate on growth by removing the spent flowers. Do this soon after flowering before the new buds get big and set. I prefer hand pinching. Just be careful so you don’t injure the buds below. Use hand snips if you are worried.
The second pruning action is for shape. Just follow the branch down to the last whorl of leaves you want to keep and cut just above those leaves. This is what I recommend to clients who wish to keep their rhododendrons from getting too big.
But what if your rhodo is too big? Now what? In this case we employ pruning action three: rejuvenation, which sounds better than renovation. This involves bravely making large cuts and significantly reducing the plant size. This works because rhodos are special. Examine their bark and look for tiny pink dots. Those are latent buds. Always aim to cut above these buds. Best case: cut above a cluster of latent buds. Then watch.
Here is one example from my work site. This rejuvenation pruning was done at a corner unit where there was a problem with vehicle sight lines. Drivers couldn’t see properly when turning. So out came the saw as soon as the request was made. This was the result.
A few weeks later…..
Rhododendrons are forgiving plants. Pinch off flower clusters (trusses) soon after flowering and prune for size. Bravely make big cuts if rejuvenation is required.
References: Fine Gardening, issue 86.