Azaleas are flowering shrubs making up part of the genus Rhododendron. Originally azaleas were classed as a different genus of plant, but now they are recognised as two of the eight sub-genera of rhododendrons - subgenus Pentanthera (deciduous), and subgenus Titsuji (evergreen).
One major difference between azaleas and the rest of the rhododendron genus is their size. Another is their flower growth; rhododendrons grow their flowers in stripers, while most azaleas have terminal blooms (one flower per flower stem). However, they have so many stems that during the flowering season they are a solid mass of colour. Azaleas are recognised by these flowers blooming all at once, in a showy display for a month or two in spring. The exception to this rule is a small group of azaleas which grow their flowers in tight terminal clusters.
The Satsuki azalea group, derived from Rhododendron indicum and related species, are very popular.
A traditional alcoholic beverage made from azalea blossoms, called Tugyonju (literally "azalea wine"), is produced in Korea.
Also, azaleas are the most common toxic plant that dogs ingest.
Azaleas grow best in well-drained soil or in plant pots in a cool, shady position. They are easily damaged by excessive soil moisture and grow best in acidic soil (4.5 - 6.0 pH). Fertilizer is optional, although some species do need regular pruning.
Several commercial nurseries in Semmes, Alabama, a suburb of Mobile, are major national suppliers of azaleas in the U.S.