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Rhododendron /ro.doˈdɛn.drɔn/

Common name: Azalea

Rhododendron is a large genus of flowering shrubs and small trees in the heath family, Ericaceae, which includes the plants commonly called azaleas. They produce showy clusters of funnel- or bell-shaped flowers in spring and are native to temperate regions across the Northern Hemisphere. Most species are evergreen or deciduous shrubs that prefer cool, moist, acidic conditions.

Fun facts

  • All parts of rhododendrons contain grayanotoxins, making the plants — and even honey made from their nectar — poisonous.
  • The genus name comes from Greek words meaning 'rose tree'.
  • The Rhododendron is the national flower of Nepal and the state flower of West Virginia and Washington.

Care summary

Sun Partial shade to dappled sun
Water Keep evenly moist; do not let dry out
Soil Acidic (pH 4.5–6), humus-rich, well-draining
Hardiness Zones 4–8 (varies by species)
Mature height 0.5–6 m (2–20 ft), by species
Pet safe Toxic to cats and dogs

Common problems

    • Test soil and lower pH
    • Feed with ericaceous fertilizer
    • Mulch with pine needles or bark
    • Plant in raised beds or mounds
    • Improve drainage before planting
    • Avoid overwatering established shrubs
    • Hose undersides of leaves
    • Apply insecticidal soap when active
    • Keep plants well watered
    • Plant away from harsh winds
    • Water deeply before ground freezes
    • Use burlap screen in winter