Sweet azalea is a deciduous shrub native to the eastern parts of the United States, where it can grow to small tree size. It thrives on moist river banks and on the slopes of the Alleghany Mountains, in places forming impassable thickets. It can best be distinguished from other North American azaleas by the shoots, which are hairless, unlike its close relatives, with which it hybridises easily.
Sweet azalea also flowers later than its close relations, not until July in Finland. It has large trumpet-shaped white flowers which are strongly scented. The scent has been described as like cinnamon or heliotrope.