Question: Can a rhododendron be cut back hard? I have one that’s gotten straggly.
Answer: Yes. You can do it all at once or spread the pruning over two or three years. The gradual approach is easier on the plant, but pruning all at once will produce a good-looking plant faster.
Make each cut just above a dormant bud, or preferably a cluster of buds, an article in the Journal of the American Rhododendron Society recommends. Dormant buds are little bumps on the stems that will grow into branches.
If you can’t find the dormant buds, just cut the plant to the desired height, wait for new growth to sprout, and then prune off the stubs, the American Rhododendron Society blog says.
Early spring is a good time to prune, but if you don’t want to lose the flowers, wait till after the shrub has finished blooming.
Mary Beth Breckenridge
Akron Beacon Journal