Encore Azaleas are selectively chosen and bred to be either dwarf or intermediate in size. Therefore, the goal when planting them is that trimming will either be unnecessary or at the very least uncommon. However, there are still good reasons to trim yours periodically.
The best time to trim your plants is indisputably after their first bloom cycle in spring ends. This is because flowers are stored in plant stems. If you were to trim your Azaleas before they formed buds in early spring, you wouldn’t get a single bloom. Not one! Well, it’s possible you might get one, but it would be very small and disappointing. For this reason, you must move quickly after your spring flowers fade. Trim the plant back however much you’d like, but cutting it back by 1/3 is usually a pretty solid trim. Use this opportunity to shape them as well if you like. Cut them into a box or a sphere and watch them flush back beautifully.
You can trim in Fall or Summer successfully, and sometimes even Winter. However, there are a few things you need to consider.
You’ll need to ensure that you are trimming your plants with enough time before freezing temperatures roll around. Trimming encourages your plant to produce new growth and new growth is very vulnerable to freezing cold. If it freezes, those new shoots will die. The plant may be fine in the long run, but it might make your plant more likely to expire during the winter.
This may mean trimming your Encores before they bloom in Fall (depending on where you’re located), which is of course undesirable. However, this is why we recommend trimming them in late spring. But if you have a plant that is growing oddly or you want to hit the next growing season with your plants ready to go and you don’t mind missing some flowers, Fall pruning works.
Summer has a different, but also very similar issue to Fall trimming. That same new growth we just discussed is also very sensitive to intense summer heat. So you prune your azaleas in summer, they flush out with new growth, and now you have to protect your plants from prolonged drought and heat exposure. Too much of either will cause these young branches to dry up and die.
Summer pruning can be done though. You’ll just need to stay very vigilant with your plants. They may require daily watering until the new growth hardens off. You can tell this has occurred when the shoots turn from light green to light brown and the leaves darken in color.
This is a bad idea in most areas, and most gardeners shouldn’t even consider it. There’s not much good that comes out of it. The plants can’t flush out safely and they lose some of the foliage that was insulating them from the winter cold.
However, gardeners in USDA Zones 9 and up can usually be successful pruning Encore Azaleas in winter because of the lack of sub-freezing winter temperatures. But sooner is always better because, once again, you don’t want to be snipping off those spring blooms.
As mentioned earlier, ideally you won’t have to trim your Encores at all. But here are some of the primary reasons that you might want to consider breaking out the shears.