|The Knap Hill and Exbury azaleas are English hybrids resulting from crosses between R. molle, R. calendulaceum, R. arborescens, and R. occidentale.
Not to be confused with the evergreen Glenn Dale hybrid of the same name. Upright, hardy, deciduous shrub with elliptic to oblong, 2 to 6 inch long leaves. Flowers are borne in huge, showy trusses of 18 to 30 blooms per cluster. Bloom time is from mid to late spring. The deciduous hybrid azalea, like its native counterpart, is known for excellent fall color and unsurpassed spring flowers.
The deciduous azalea is usually less picky about soil conditions, though it too prefers well-drained and acid conditions. Though azaleas have a potentially large list of possible pest and disease problems, they are usually trouble free if planted correctly in proper cultural conditions.