Just what you wanted to hear now that it’s so hot and humid: time for some more yard work, if you have azaleas, that is. Yes, one of our favorite Southern spring-flowering shrubs benefits from a bit of pruning this time of year.
Most of the flowering azalea shrubs planted around our homes and businesses are the Southern Indica variety. These are the ones with the big, orchid-like flowers in white, pink, magenta, and salmon. Their large leaves are covered with rusty-colored hairs, as are the stems. This makes them rather scratchy to work with, so I wear gloves and long sleeves and pants. This is quite the uncomfortable outfit for working outside on hot summer days, so I start early and take a break from pruning as the sun gets high.
It is best to prune azaleas after they bloom but before the Fourth of July because next year’s flowers are formed on this year’s stems. So, if you wait until later in the summer, or on into fall and winter to do any pruning, you will be cutting off the flower buds that would bloom next spring.
There are two basic ways to prune an Indica azalea: Heading (also known as tipping or shearing) and thinning. Heading is when you do a light trimming of the longer stems that are sticking out of the main shrub. It’s best to use a sharp pair of hand-held pruning shears, but electric or gas-powered shears make the job go a lot quicker. Either way, this creates a uniform shape and is suitable for a formal yard or garden.
Thinning is done by using hand shears or loppers to reach into the center of the shrub to remove whole stems or branches for a more natural shape. The stems are pruned back to the next node or joint back down the larger branch that they are attached to. This whole-stem removal allows for better air circulation and helps keep the shrub free of disease and insect problems that can sometimes be made worse by heading or shearing.
Renewal pruning is a form of heading, which involves basically cutting down the shrub, leaving only the main trunk(s) and no foliage. This is very stressful for the plant and could kill it if done during extreme hot, dry weather. I would recommend this only in extreme cases, where the shrubs are completely overgrown and neglected. Renewal can also be done in stages to minimize the effect on the plant (such as doing the front, back, top and sides at different times) and then allowing it to regrow and recover gradually.
An additional pruning technique for the large azaleas is called “limbing up” or “upsizing.” You cut off the lower limbs of a well-branched mature azalea and gradually prune the shrub into a tree form over several years. I have seen this pruning technique at some beach hotels and the resulting little azalea trees are remarkably beautiful.
For more information on Azalea selection, care and pest problems, please see our fact sheets at the Clemson Extension Home and Garden Information Center https://hgic.clemson.edu/?s=azaleas . For pruning information, go to https://hgic.clemson.edu/factsheet/pruning-shrubs/.
Here is a link to a short video on pruning azaleas with Dr. Jerry Parsons , horticulture specialist from Texas A&M AgriLife Extension https://aggie-horticulture.tamu.edu/media/videoarchive/practices/pruningshrubs1.wmv.
Trish DeHond is the home horticulture agent and Master Gardener coordinator for Clemson Extension in Darlington and Florence counties. She can be reached by email at firstname.lastname@example.org