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Herbaceous Perennial

Eryngium × zabelii 'Big Blue'
  • RHS AGM

sea holly 'Big Blue'

'Big Blue' is an upright, herbaceous perennial to 75cm with spiky, highly-divided, silvery-green foliage. The stiff, branched stems are topped with blue, thimble-shaped flowerheads surrounded by a ruff of prickly, silvery-blue bracts

Synonyms
Eryngium 'Big Blue'
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Size
Ultimate height
0.5–1 metres
Time to ultimate height
2–5 years
Ultimate spread
0.1–0.5 metres
Growing conditions
Chalk
Loam
Sand
Moisture
Well–drained
pH
Acid, Alkaline, Neutral
Colour & scent
StemFlowerFoliageFruit
Spring Green Grey Silver
Summer Blue Green Grey Silver
Autumn Green Grey Silver
Winter
Position
  • Full sun
Aspect

South–facing or West–facing or East–facing

Exposure
Exposed or Sheltered
Drought resistance
Yes
Hardiness
H5
Botanical details
Family
Apiaceae
Native to the UK
No
Foliage
Deciduous
Habit
Bushy
Genus

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

Name status

Accepted

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How to grow

Cultivation

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

Propagation

Propagate by root cuttings in late winter

Suggested planting locations and garden types
  • Gravel garden
  • Architectural
  • City and courtyard gardens
  • Coastal
  • Cottage and informal garden
  • Patio and container plants
  • Prairie planting
  • Banks and slopes
  • Cut flowers
  • Flower borders and beds
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

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