Azaleas are commonly planted outside during the spring and fall. Container-grown azaleas are placed in the ground whenever the soil is workable as long as there is plenty of water to keep the root area moist.
Azaleas ready for spring planting are usually in flower so you can see what the shrub will look like. Fall-planted azaleas have the time to establish their roots before the extreme heat of summer arrives.
Azaleas planted in the spring need regular watering until fall to survive the summer heat. Fall-planted azaleas are not in bloom so you do not know what the blossom actually looks like until next year.
Azaleas grown in containers may be root-bound when purchased. Check the roots to see if they are circling the root ball. If they are, make four equally spaced cuts 1/4 inch deep to encourage the roots to grow outward. Gently spread the roots out when placing the azalea bush in its planting hole.