Azaleas are members of the Heath family of plants and are both of the species and genus Rhododendron. They come in many varieties, but all have the same basic needs -- plenty of well-drained, low-pH potting or treated soil.
Azaleas grow in most of the United States. The largest variety grows in the southeastern part of the country, however.
Azaleas need a low-pH type of soil. If possible, buy potting soil made just for azaleas. If that is not possible, mix milled sphagnum peat moss with your regular potting soil.
Soil must be pH 4.5 to 5.5 and well-drained. Azaleas do not like to stand in water.
Azaleas are considered perennials, so will do well in the garden if the soil conditions are right. A large hole filled with potting soil made for azaleas will provide what they need.
Azaleas are fairly shallow-rooted, so potting soil with a low pH works well either in the garden or in containers. Keep them moist, but not wet, and they should do well for you.