Too much nitrogen in early summer may encourage vegetative growth at the expense of flower bud formation, so limit fertilizer applications to the fall or spring or skip the fertilizer all together. Although azaleas are well adapted to partial shade, deep shade produces spindly, weak growth and few flower buds. Azaleas usually won’t flower well if planted under trees with dense foliage, such as maples, beeches, and pines. Plant in the diffused light under widely spaced, high-crowned trees like oaks and tulip poplars. Deer and rabbits may eat many of the flower buds as they browse in the winter, particularly if the weather is harsh and other food is scarce. Flower buds can also be damaged by cold, dry winds, particularly when warm winter weather is followed by a period of bitter cold.

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The damage you describe is that of the black vine weevil, a small nocturnal weevil that, in its larval stage, feeds on azalea and rhododendron roots. As the new leaves expand in the spring, adult weevils emerge from the soil and make nightly visits to the leaves to feed, chomping sections out of the margins of the new leaves. Black vine weevils can’t fly, so they don’t spread rapidly. They spread most commonly in container plants and a few larvae in a single pot may start an infestation that may damage dozens of plants in your garden. Black vine weevils are very hard to get rid of, so quarantine new plants for several months before planting to make sure they are not infested. A pesticide containing imidacloprid may help control them.

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Prune azaleas just after they have finished flowering. Remove individual branches back to the spot where they join a larger branch. New flower buds for next spring’s bloom are set by midsummer, and any pruning after mid-June could result in diminished flower production next year. Avoid shearing azaleas since it results in a proliferation of unhealthy, twiggy growth. Check azaleas for wilting or dead branches in late summer that may be the result of fungal cankers. These branches should be pruned back to clean white wood that is not infected while the weather is dry to prevent the spread of diseases. Old azaleas that have grown too large for their space in your garden can be brought down in size by cutting the large branches back severely. New growth will spring from the stubs that are left.

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