In late spring and early summer, clusters of brilliant rhododendron blossoms, from stark white to cardinal red, are a familiar and lovely sight across North Carolina’s mountain peaks and balds — and in front yards. But despite their beauty, evergreen rhododendrons are hardy and tough — and that calls for annual pruning to make sure they don’t become overgrown. Donna Teasley, a consumer horticulture agent at the Cooperative Extension of Burke County, walks us through a few tips for keeping your plants spick-and-span.
1. Be prepared to sacrifice some buds.
To get your rhododendrons shaped up, you may have to do some severe pruning. Teasley stresses that the plants can handle it — and it’s necessary — but it will likely take a few years for the plant to fully recover and produce blooms again. Make sure you’re ready for this before you start chopping.
2. Go low.
If you have an overgrown rhododendron, the best place to prune is on those long, leggy stems at the base of the shrub.
3. Take your time.
Teasley explains that, ideally, the process of severe pruning will take three years. The first year, cut out a third of those long, leggy stems. The next year, another third. The year after that, the final third. “Even though you can severely prune your rhododendrons, it’s not something you can do all in one year if you want it to rejuvenate correctly,” Teasley says. “It can end up killing the plant.”
4. Do your research.
Teasley notes that some varieties of rhododendrons respond better than others to pruning. If you don’t know what variety you have, try to find out before you prune. Hint: Google is your friend.
5. Wait for the end of spring.
“Rhododendrons are best pruned right after they’ve finished blooming, at the end of spring,” Teasley says. In Burke County, that’s mid- to late May. Expect to prune a couple of weeks before that if you live in lower elevations.
6. Use the right tools.
“You’ll use different tools depending on the size of your rhododendron and how much you’re pruning off,” Teasley says. “For example, if you have a small rhododendron and want to pop out the split blooms, you can use your hands. If you’re getting into some more severe pruning, you’ll need some pruners, and if you’re dealing with an older, larger plant, you may even want to use a lopper.”
7. Go easy on the fertilizer.
Pruning encourages the plant to grow back quickly, and that leaves it susceptible to disease and insect damage. Keep in mind that the shrub will not need as much fertilizer. In fact, a heavy dose of the stuff could indirectly harm it.
Have more questions? Contact the NC Cooperative Extension of Burke County:
(828) 764-9480 or burke.ces.ncsu.edu