Eryngium maritimum

RHS Plant Profile
sea eryngo

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sea eryngo RHS

Other common names

sea eryngium, sea holly, sea holm, celyn y môr

Plants for pollinators
Herbaceous Perennial
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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

Position

Full sun

Soil Types

Sand

Max Height

0.5-1 metres

Max Spread

0.1-0.5 metres

Size

Time to Maturity
2–5 years
Max Spread
0.1-0.5 metres
Max Height
0.5-1 metres

Growing Conditions

Sand
Moisture
Well–drained
pH
Alkaline or Neutral

Position

Full sun
Aspect
West–facing or East–facing or South–facing
Exposure
Exposed or Sheltered
Hardiness

Hardiness Ratings

All ratings refer to the UK growing conditions unless otherwise stated. Minimum temperature ranges (in degrees C) are shown in brackets

  • H1A: under glass all year (>15C)
  • H1B: can be grown outside in the summer (10 - 15)
  • H1C: can be grown outside in the summer (5 - 10)
  • H2: tolerant of low temperatures, but not surviving being frozen (1 to 5)
  • H3: hardy in coastal and relatively mild parts of the UK (-5 to 1)
  • H4: hardy through most of the UK (-10 to -5)
  • H5: hardy in most places throughout the UK even in severe winters (-15 to -10)
  • H6: hardy in all of UK and northern Europe (-20 to -15)
  • H7: hardy in the severest European continental climates (< -20)
H5
Drought Resistance
Yes

Colour & Scent

Season Stem Flower Foliage Fruit
Spring
Summer
Autumn
Winter

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