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Eryngium planum 'Bethlehem'

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© RHS 1999

Characteristics

Plant type

Herbaceous Perennial

Habit

Clump-forming

Resilience

Hardiness

old H4 (hardy)

Colour

Flower

Blue in Autumn and Summer

Foliage

Dark Green in Autumn, Spring, Summer and Winter

Size

Ultimate height

0.5-1 metres

Ultimate spread

0.1-0.5 metres

Time to ultimate height

2-5 years


Preferred common name

blue eryngo 'Bethlehem'

Family

Apiaceae


Eryngium can be annuals, biennials or perennials with simple or divided leaves, often spiny edged, and cone-like flower-heads often surrounded by an involucre of conspicuous spiny bracts

'Bethlehem' is a perennial forming a clump of oblong dark green leaves and branched stems bearing small, slate-blue flower-heads with narrow bracts

How to grow

Sunlight

  • Full sun

Aspect

  • South-facing, East-facing or West-facing
  • Exposed

Cultivation

Grow in dry, well-drained soil that is poor to moderately fertile. Full sun is essential as is protection from winter wet

Soil

  • Well-drained
  • Acid, Alkaline or Neutral
  • Sand, Loam or Chalk

Propagation

Propagate by root cuttings in late winter

Suggested planting locations and garden types

Coastal, Cottage/Informal Garden, Flower borders and beds, Cut Flowers, Gravel Garden or Wildlife Gardens


How to care

Pruning

Although you can cut back flower stems after flowering the seedheads are a very attractive feature so are usually left over winter

Pests

Can get leaf and bud eelworms

Diseases

May be affected by powdery mildews and root rot