Azaleas and nearly all spring-flowering shrubs and trees need to be pruned soon after flowering. A new fold has developed in recent years. Reblooming azaleas bloom in spring and fall. So what do we do?
First of all, any necessary pruning should be performed after the spring blooming season. Don’t prune these shrubs in the fall. There are two main reasons for this.
The first is that you will cut off next spring’s flowers if you prune in the fall. More importantly, fall pruning encourages new growth to develop. If mild conditions follow the pruning, plants will begin to sprout new growth. This could lead to winterkill.
In general, I discourage most fall pruning unless it is performed when plants are already dormant and the chances for regrowth are minimal. Exceptions would be plants that have become unsightly due to storm damage.
Reblooming azaleas are a great addition to our landscapes. The biggest complaint about azaleas has always been that they are only colorful for a short time. The rebloomers change that. Their most impressive blooming season is still the spring, but they offer additional color in the fall.
When I explain that plants need only be pruned in spring and even then, not as much as traditional azaleas, most folks like the idea of low maintenance. Some are concerned that the shrubs might get too large.
For those people, I stress paying attention to the cultivar. Some naturally stay small and some grow larger. Those customers wanting two to three-foot azaleas should not choose cultivars that grow five feet tall. Keeping them trimmed to the desired size will limit blooming.
In recent years there have been many new cultivars developed in numerous colors. Most nurseries carry several different ones.
However, after a number of years, if the shrubs have outgrown their space, they can be renewal pruned after spring flowering and maybe lightly trimmed once more that summer. By the following spring, they should be nearly back to normal.
Another consideration to reblooming azaleas is that they require a bit more sun than standard ones. For most gardeners, this is a positive trait. In general, azaleas struggle in our climate because they get too much sun. Rebloomers grow better under these conditions. In fact, they often struggle in locations favorable to traditional azaleas.
Perhaps eventually prices might be comparable to traditional azaleas, but at present, you can expect to pay about twice the price for rebloomers. Even at that, they are far from overpriced, and they are well adapted to our sandy acid soils.
Some people think that because of the additional bloom, these azaleas might require more fertilizer. This isn’t the case. When fertilizing, only use fertilizers that are for acid-loving plants. Also, overfertilizing could make azaleas more susceptible to lace bugs.
Lace bugs should be treated early, and since so many folks around here plant azaleas, you’ll likely encounter them. A systemic insecticide containing imidacloprid or acephate works well. It’s often helpful to alternate these chemicals, so pests don’t build up any type of resistance.
Ted Manzer teaches agriculture at Northeastern High School.