Types of azaleas: evergreen vs deciduous, native vs Asian
Azaleas are all rhododendrons botanically -- they are members of the genus *Rhododendron* and are not scientifically distinguished from rhododendrons. The horticultural distinction is loose: plants commonly sold as "azaleas" tend to have smaller leaves, smaller flowers, and different (usually.
Azaleas are all rhododendrons botanically — they are members of the genus Rhododendron and are not scientifically distinguished from rhododendrons. The horticultural distinction is loose: plants commonly sold as "azaleas" tend to have smaller leaves, smaller flowers, and different (usually funnel-shaped) flower forms compared to plants sold as "rhododendrons."
The garden distinction that matters most is between evergreen azaleas (the spring-blooming Asian types that dominate suburban landscapes) and deciduous azaleas (primarily native North American species with more naturalistic character and outstanding fall color).
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Evergreen azalea groups
Per NC State Extension, the main evergreen azalea groups available in American nurseries:
Kurume azaleas (Rhododendron Kurume hybrids)
Small-leaved, compact shrubs (3–5 feet) with small (1–1.5 inch) flowers in dense clusters. Among the most popular spring-blooming azaleas in zones 6–8. Examples: 'Coral Bells', 'Hino Crimson', 'Hinodegiri'.
Gable hybrids
Bred in the 1920s–40s for cold hardiness (zones 5–7). Larger flowers than Kurumes; more upright habit. Examples: 'Herbert' (purple), 'Stewartstonian' (red), 'Rosebud' (pink double).
Glenn Dale hybrids
Developed by USDA in the 1940s; bred for late bloom season and large flowers. Hardy in zones 6–8. Examples: 'Glacier' (white), 'Treasure' (white with pink flush).
Girard hybrids
Bred for zone 5 hardiness with larger flowers. Examples: 'Girard's Crimson' and related series.
Southern Indian hybrids
Large shrubs (5–10 feet) for zones 7–10. Classic Southern landscape azalea. Examples: 'Formosa' (lavender-purple; the most common Southern azalea), 'George Lindley Tabor', 'Pride of Mobile'.
Encore series (Robin Hill types and others)
The Encore Azalea series (proprietary, developed in the 1980s–2000s) is the most significant azalea breeding development of the past 40 years. Per Clemson HGIC, Encore azaleas bloom in spring like standard evergreen azaleas, rebloom in summer, and again in fall. They are available in zones 6–9 and represent a different performance standard from traditional evergreen types.