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Herbaceous Perennial

Eryngium maritimum
  • RHS Plants for pollinators

sea holly

A clump-forming perennial to around 60cm in height. Leaves are waxy, stiff and spiny, blue-green in colour with white veins. Flowerheads of globular blue umbels are borne in April to September surrounded by collars of spiky bracts

Other common names
sea eryngium
sea eryngo
see moresea holm
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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
Sand
Moisture
Well–drained
pH
Alkaline, Neutral
Colour & scent
StemFlowerFoliageFruit
Spring Blue Green Grey Silver White
Summer Blue Green Grey Silver White
Autumn Green Grey Silver White
Winter Green Grey Silver White
Position
  • Full sun
Aspect

West–facing or East–facing or South–facing

Exposure
Exposed or Sheltered
Drought resistance
Yes
Hardiness
H5
Botanical details
Family
Apiaceae
Native to GB / Ireland
Yes
Foliage
Semi evergreen
Habit
Bushy, Clump forming
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

Correct

Plant range
Europe

How to grow

Cultivation

Occurs naturally on coast lines in sand dunes or shingle so prefers free-draining, sunny conditions

Propagation

Propagate by seed in autumn

Suggested planting locations and garden types
  • Gravel garden
  • Coastal
  • Cottage and informal garden
  • Wildlife gardens
Pruning

No pruning required

Pests

May be susceptible to leaf and bud eelworms, and slugs and snails

Diseases

May be susceptible to root rot and powdery mildews

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