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Eryngium × tripartitum AGM

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© RHS 1999

Characteristics

Plant type

Herbaceous Perennial

Habit

Clump-forming

Resilience

Hardiness

H5 (hardy - cold winter)

Colour

Flower

Dark Blue in Autumn and Summer

Foliage

Green and Grey/Silver in Autumn, Spring and Summer

Stem

Dark Blue in Summer

Size

Ultimate height

0.5-1 metres

Ultimate spread

0.1-0.5 metres

Time to ultimate height

2-5 years


Preferred common name

tripartite eryngo

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

E. × tripartitum is an herbaceous perennial with a basal rosette of grey-green leaves, and erect, much-branched, violet-blue stems bearing cone-like purple heads surrounded by narrow, dark blue 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, Wildlife Gardens or Mediterranean Climate Plants


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