• AGM plants

    AGM plants have been through a rigorous trial and assessment programme. They are:

    • Excellent for ordinary use in appropriate conditions
    • Available to buy
    • Of good constitution
    • Essentially stable in form & colour
    • Reasonably resistant to pests & diseases

Eryngium alpinum

alpine eryngo

alpine eryngo

© RHS 1999

  • Other common names alpine eryngo

  • Family Apiaceae

  • 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

  • Details E. alpinum is an erect herbaceous perennial to 90cm, with heart-shaped, glossy dark green basal leaves. Large, cone-like, purplish flower-heads surrounded by 6cm in length vivid blue, spiny bracts, borne on blue stems

  • Plant range W & C Balkans

Characteristics

  • Foliage Deciduous

  • Habit Clump-forming

  • 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

Colour

Sunlight

  • Full Sun

  • Aspect South-facing or East-facing or West-facing

  • Exposure Exposed

Soil

  • Sand

    Sand

  • Loam

    Loam

  • Chalk

    Chalk

  • MoistureWell-drained

  • SoilSand, Loam, Chalk

  • pHAcid, Alkaline, Neutral

Size

  • Ultimate height 0.5-1 metres

  • Ultimate spread 0.1-0.5 metres

  • Time to ultimate height 2-5 years

How to grow

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

Propagation Propagate by seed sown in pots in a cold frame as soon as seed is ripe

Suggested planting locations and garden types Flower borders and beds Cut Flowers Coastal Cottage & Informal Garden Gravel Garden Wildlife Gardens

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

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