Rhododendron ( Sea Shell Glenn Dale Azalea )
The Glenn Dale evergreen hybrids were formulate in Maryland from R. indicum , R. kaempferi , R. simsii and many other species and hybrids . They are compact , spreading , evergreen plant azalea developed primarily for cold hardiness along the mid - Atlantic State Department . heyday are carry in showy trusses of 1 to 4 per cluster . Bloom sentence is belated April in warmer area and as late as mid - June in cooler climate ....