Answer: Azaleas are best trimmed in spring after blooming. This way they will have plenty of time to regrow shoots which will set buds in late summer and fall for next year's bloom. If you prune them in winter, the bush will not suffer, but you will be cutting away most of the buds for that spring's blooms.
If you prune them back heavily, you may need to do some tipping of vigorous upright shoots that regrow in order to encourage branching and build a bushier plant.
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