• 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

Helleborus × sternii Blackthorn Group

Hellebore Blackthorn Group

Hellebore Blackthorn Group

© � RHS 2000

  • Other common names Hellebore Blackthorn Group

  • Synonyms Helleborussternii 'Blackthorn Strain'

  • Genus Helleborus can be rhizomatous, herbaceous or semi-evergreen perennials forming a clump of pedate basal leaves, or evergreen with erect, leafy stems. Large, bowl-shaped flowers are borne in loose clusters in late winter or spring

  • Family Ranunculaceae / Ranunculaceae

  • Species Blackthorn Group are evergreen perennials to 45cm with purplish biennial stems bearing leaves composed of three bluish-green, pale-veined leaflets. Nodding, pale pinkish-green flowers 3-5cm in width are borne in open clusters


  • Foliage Evergreen

  • Habit Clump-forming

  • Toxicity Ingestion may cause severe discomfort



  • Full Sun

  • Partial Shade

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

  • Exposure Sheltered


  • Chalk


  • Chalk


  • Chalk


  • MoistureMoist but well-drained

  • SoilClay, Loam, Chalk

  • pHAlkaline, 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 Thrives in neutral to alkaline soils that are moist, fertile and humus-rich. Partial shade is ideal but can tolerate full sun. Provide shelter from strong, cold winds. Mulch annually in autumn

Propagation Propagate by seed in pots in a cold frame as soon as seed is ripe or propagate by division after flowering in early spring or late summer. Named cultivars do not come true from seed

Suggested planting locations and garden types Flower borders and beds Cut Flowers Underplanting of Roses and Shrubs Cottage & Informal Garden

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