Also consider the soil, drainage and light exposure. May. Azalea blooming season is usually classified as early, mid or late. Here is a tip if you do decide to extend the blooming season. Do not mix early and mid-season azaleas in the same bed. The fading blooms of the early flowers will detract from the newly opening blooms of the mid-season flowers.
Azaleas do best when grown in filtered sunlight and a highly organic soil.
An ideal exposure would be under the branches of a large tree which drops its leaves in winter. An east or north facing side of the house or fence would also be a good location. However, dense, all day shade can result in leggy plants with skimpy blooms. The soil must be well-drained. An ideal soil would be a sandy loam high in organic matter.