• 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

Blechnum penna-marina

alpine water fern

  • Other common names alpine water fern

  • Family Blechnaceae

  • Genus Blechnum are mostly evergreen ferns with erect or creeping rhizomes and simply pinnate, leathery fronds, the fertile ones usually erect, the sterile often spreading

  • Details B. penna-marina is an evergreen fern forming a mat of spreading, simply pinnate, dark green sterile fronds to 15cm in length, with narrower, erect fertile fronds, the young fronds often reddish

  • Plant range S Hemisphere

Characteristics

  • Foliage Evergreen

  • Habit Mat 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)

    H4

Colour

Sunlight

  • Full Shade

  • Partial Shade

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

  • Exposure Exposed or Sheltered

Soil

  • Loam

    Loam

  • Sand

    Sand

  • MoistureMoist but well-drained, Poorly-drained

  • SoilLoam, Sand

  • pHAcid, Neutral

Size

  • Ultimate height 0.1-0.5 metres

  • Ultimate spread 0.5-1 metres

  • Time to ultimate height 5-10 years

How to grow

Cultivation Easy to grow in most cool, moist, shaded sites

Propagation Propagate by sowing spores (may not come true) in mid to late summer or by division in spring

Suggested planting locations and garden types Flower borders and beds Banks and Slopes Underplanting of Roses and Shrubs City & Courtyard Gardens Cottage & Informal Garden Patio & Container Plants

How to care

Pruning Dead or damaged fronds may be removed as necessary

Pests Generally pest free outdoors

Diseases Generally disease free outdoors

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