• AGM plants

    AGM plants have been through a rigourous trial and assessment programme. They are:

    • Excellent for ordinary use in appropriate conditions
    • Available to buy
    • Of good constitution
    • Essentially stable in form & colour
    • Reasonably resistant to pests & diseases

Actaea rubra

Black cohosh

Black cohosh

© � RHS 2002

  • Other common names Black cohosh

    Rattlesnake herb
    Red baneberry

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  • Synonyms Actaea arguta
    Actaea erythrocarpa

    Actaea rubra subsp. arguta
    Actaea spicata 'Erythrocarpa'
    Actaea spicata subsp. erythrocarpa
    Actaea spicata var. erythrocarpa
    Actaea spicata var. rubra

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  • Genus Actaea are rhizomatous herbaceous perennials with compound leaves and small creamy-white flowers in short, erect, simple or branched terminal racemes, followed either by poisonous red, black or white berries, or by star-shaped clustered brown follicles

  • Family Ranunculaceae / Ranunculaceae

  • Species A. rubra is a clump-forming herbaceous perennial to 50cm, with bright green, divided leaves and spikes of small, fluffy white flowers in late spring and early summer, followed by glossy scarlet berries

  • Plant range North America


  • Foliage Deciduous

  • Habit Clump-forming

  • Toxicity Toxic if ingested



  • Partial Shade

  • Aspect East-facing or West-facing or North-facing

  • Exposure Sheltered


  • Chalk


  • Chalk


  • MoistureMoist but well-drained, Poorly-drained

  • SoilLoam, Clay

  • pHAcid, Neutral


  • Ultimate height

    0.1-0.5 metres

  • Ultimate spread

    0.1-0.5 metres

  • Time to ultimate height

    2-5 years

How to grow

Cultivation Best grown in cool, moist, reasonably fertile soil in partial shade but will tolerate most soils if enriched with organic matter

Propagation Propagate by seed sown in pots in a cold frame in autumn or by division in early spring

Suggested planting locations and garden types Flower borders and beds Wildflower meadow Cottage & Informal Garden

How to care

Pruning Cut back after flowering or fruiting

Pests Generally pest free

Diseases Generally disease free

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