Crambe maritima

RHS Plant Profile
sea kale

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sea kale RHS
sea kale RHS
sea kale RHS
sea kale RHS

Other common names

sea cabbage, sea colewort, seakale, ysgedd arfor

RHS Recommended

Plants for pollinators
Herbaceous Perennial
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A robust herbaceous perennial to 75cm, forming a clump of large, lobed, wavy-edged blue-green leaves, with thick stems bearing dense racemes to 60cm across of small white flowers in early summer

Position

Full sun, Partial shade

Soil Types

Chalk, Loam, 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

Chalk Loam Sand
Moisture
Well–drained
pH
Acid or Alkaline or Neutral

Position

Full sun Partial shade
Aspect
West–facing or South–facing or East–facing
Exposure
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)
H7

RHS Recommended: for People & Planet

RHS Recommended Plants for People & Planet

For Water Resilience

Plants for Flood Resilience

Plants that can help manage heavy rain by catching rainfall, slowing surface run-off, encouraging water into the soil or taking it up through their roots, contributing to flood resilient gardens.

Plants for both Wet and Dry Conditions

Plants that cope with changing soil moisture, including wet winters and extended summer dry. Once established, they grow as wet and dry conditions alternate.

For Temperature Resilience

Plants for Temperature Cooling

Plants that cool air temperature by providing shade, transpiration, or reflection to reduce heat impact on people, animals, soil or other ground surface.

Plants for Wind Shelter

Plants with dense canopies often grown as a tall thick hedge or grouping can block wind and shelter gardens, buildings and people.

For Carbon Storage

Plants for Carbon Storage

Plants that can take up carbon (CO₂) through photosynthesis and store it within the plant or deposit it by their roots into the soil.

For Biodiversity

Plants for Pollinators

Plants that have flowering properties (pollen and/or nectar) that are particularly beneficial for pollinating insects such as bees, butterflies and hoverflies.

Growing conditions for maximum benefit

This plant will provide the maximum benefits if it is healthy and allowed to grow to maturity

For Bio-Diversity

  • Plants for Pollinators

Colour & Scent

Fragrance Flower
Season Stem Flower Foliage Fruit
Spring
Summer
Autumn
Winter

Botanical Details

Family
Brassicaceae
Native to GB/Ireland
Yes
Foliage
Deciduous
Habit
Clump forming
Genus
Crambe are robust annuals and perennials with large, simple or divided leaves and racemes or large panicles of small, fragrant white flowers
Name Status
Correct
Plant Range
Europe to Caucasus

How to Grow

Cultivation

Natually occurs in shingle and sand in coastal areas. Ideally grow in well-drained soil in full sun although it will tolerate poor soil and partial shade. Provide shelter from strong winds

Propagation

Propagate by seed sown in pots in a cold frame in spring or autumn or propagate by division in early spring or take root cuttings in winter

Suggested planting locations and garden types

  • Coastal
  • Cottage and informal garden
  • Gravel garden
  • Wildlife gardens
  • Cut flowers
  • Flower borders and beds

Pruning

Cut down to ground level in autumn

Pests

May be susceptible to slugs and caterpillars

Diseases

May be susceptible to club root