Azaleas are often pot bound, so be sure to check this carefully. If yours are pot bound, score the roots with a knife in about three locations from top to bottom. Place the azalea in the hole and backfill with soil, tamping and watering to settle. Apply 3 to 4 inches of mulch. Watch the moisture the first year, particularly in light of the current weather patterns.
Azaleas have shallow root systems, so maintain moisture and apply fresh mulch yearly.
Feed existing azaleas in late winter and mid-summer with an azalea fertilizer. We get a lot of questions about pruning. It is best to prune after spring bloom if needed. Try to do as little pruning as possible after mid-summer since next year's buds are beginning to form. The lacebug seems to be the azalea's archenemy.