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Helleborus × sternii Blackthorn Group

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© RHS 2000

Characteristics

Plant type

Herbaceous Perennial

Habit

Clump-forming

Toxicity

Ingestion may cause severe discomfort; skin irritant

Resilience

Hardiness

old H3-4 (intermediate between H3 and H4)

Colour

Flower

Pale Green and Pale Pink in Spring and Winter

Foliage

Blue and Green in Autumn, Spring, Summer and Winter

Stem

Green and Purple in Autumn, Spring, Summer and Winter

Size

Ultimate height

0.1-0.5 metres

Ultimate spread

0.1-0.5 metres

Time to ultimate height

2-5 years


Preferred common name

hellebore Blackthorn Group

Family

Ranunculaceae


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

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

Synonym(s)

  • Helleborus × sternii 'Blackthorn Strain'

How to grow

Sunlight

  • Full sun
  • Part shade

Aspect

  • North-facing, South-facing, East-facing or West-facing
  • Sheltered

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

Soil

  • Moist but well-drained
  • Alkaline or Neutral
  • Clay, Loam or Chalk

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

Cottage/Informal Garden, Flower borders and beds, Cut Flowers or Underplanting of Roses and Shrubs


How to care

Pruning

Remove faded or damaged foliage as the flowers appear

Pests

Prone to hellebore aphid and snails

Diseases

May be affected by hellebore leaf spot and a virus