Azaleas vary greatly in their size depending upon the specific type. According to the Azalea Society of America, there are several thousand varieties of azaleas. Large azaleas may reach more than 10 feet tall, whereas smaller varieties may only reach a maximum height of 12 inches.
Azaleas are a part of the rhododendron genus and are identified between the rhododendron by their leaf shape and the numbers of stamens -- azaleas normally have only five or six stamens and their leaves are pointier than rhododendrons. If they are properly cared for, azaleas can grow for up to several hundred years.
Gardening books and catalogs frequently list the top height that the shrub will reach in 10 years. The Azalea Society of America suggests that homeowners select shrubs that are 3 to 5 feet tall to reduce the amount of time spent pruning the bush.
Larger azalea shrubs that outgrow their current location can be transplanted to a new location, thanks to their shallow root systems. The U.S. National Arboretum suggests transplanting in the early spring or fall to reduce shock.