Don't Settle for Scraggly Azaleas
Shaping your azaleas is like getting a good haircut; the improvement is noticeable but the amount removed isn't. With a little attention, your plants will be as pretty as a picture. Artful pruning can get these shrubs in shape and keep them that way.
If you trim azaleas during the wrong season, you will cut off next year's blossoms. That's because azaleas bloom on old wood, so they produce flowerbuds on last year's growth. You won't hurt the plant by pruning during warm months, but if you want flowers, hide your clippers after spring. The best time to trim azaleas is just after they've finished blooming.
Never prune azaleas with electric shears. Hand pruners are essential for doing the job right. If your shrubs haven't been shaped for a while, they've probably grown long woody stalks with clusters of foliage at the tips. Reach inside the plant to cut these stalks off where they join each branch. Not only will all cuts be hidden by surrounding foliage, but this technique also allows sunlight to penetrate to the center of the plant, encouraging new growth and flowers. (Flat-topping your azaleas by trimming only the ends of branches results in dense twiggy growth with sparse foliage.)
Though you may end up with an alarmingly large pile of cut-off stalks, don't worry. Your azaleas won't look like they've just been butchered. That's because this pruning method allows the shrubs to maintain their natural, airy shape.
Choose the Right Tool
Small prunes are fine for trimming pencil-width stems, but long-handled loppers are the tool of choice when cutting branches ½ inch to 1 ½ inches in diameter. The handles provide the leverage needed to make clean cuts.
If you see pale, fuzzy buds curled tight on the tips of branches, it's too late to prune azaleas without cutting off next year's flowers.