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Hydrangea /haɪˈdɹeɪnd͡ʒə/

Common name: Hydrangea · Hortensia

Hydrangea is a genus of about 70 species of flowering shrubs and vines in the family Hydrangeaceae, native to Asia and the Americas. Best known for their large showy flower heads in mophead or lacecap forms, many species bloom from early summer into autumn. Flower color in bigleaf hydrangeas famously shifts with soil chemistry.

Fun facts

  • Bigleaf hydrangeas bloom blue in acidic soil and pink in alkaline soil because aluminum availability changes the pigment color.
  • The genus name comes from the Greek for "water vessel," referring to the cup-shaped seed capsules — and the plant's thirst.
  • The showy "petals" of lacecap hydrangeas are actually sterile flowers surrounding tiny fertile ones.
  • Hydrangeas contain cyanogenic glycosides, making all parts of the plant toxic if eaten.

Care summary

Sun Morning sun with afternoon shade
Water Generous and consistent; wilts quickly when dry
Soil Rich, moist, well-drained soil
Hardiness Zones 3–9 (varies by species)
Mature height 1–3 m (3–10 ft) depending on species
Pet safe Toxic to cats and dogs if ingested

Common problems

    • Improve air circulation around plants
    • Water at the base, not overhead
    • Remove and destroy affected leaves
    • Cover shrubs when frost is forecast
    • Delay pruning until growth starts
    • Water deeply in dry weather
    • Mulch to keep roots cool and moist
    • Prune only immediately after flowering
    • Avoid cutting stems in late summer