• 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

Calamagrostis × acutiflora 'Karl Foerster'

feather reed-grass 'Karl Foerster'

feather reed-grass 'Karl Foerster'

© RHS 1997

  • Other common names feather reed-grass 'Karl Foerster'

  • Synonyms Calamagrostis 'Stricta'

  • Family Poaceae

  • Genus Calamagrostis are robust rhizomatous perennial grasses, forming tufts of linear leaves, with erect stems bearing dense branching flowering panicles in summer

  • Details 'Karl Foerster' is a clump-forming deciduous perennial grass with flat, arching leaves to 90cm in length, and bronze flowering panicles that fade to pale brown

Characteristics

  • Foliage Deciduous

  • Habit Tufted

  • 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

Colour

Sunlight

  • Full Sun

  • Partial Shade

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

  • Exposure Exposed or Sheltered

Soil

  • Chalk

    Loam

  • Chalk

    Chalk

  • Chalk

    Sand

  • Chalk

    Clay

  • MoistureWell-drained, Moist but well-drained

  • SoilLoam, Chalk, Sand, Clay

  • pHAcid, Alkaline, Neutral

Size

  • Ultimate height 1-1.5 metres

  • Ultimate spread 0.5-1 metres

  • Time to ultimate height 2-5 years

How to grow

Cultivation Easy to grow in most moist, humus-rich, well-drained fertile soils, but will tolerate all but the poorest soils

Propagation Propagate by division in mid-spring

Suggested planting locations and garden types Flower borders and beds Low Maintenance Architectural Cottage & Informal Garden Prairie Planting

How to care

Pruning Cut back old stems to the ground in early spring before growth resumes

Pests Generally pest free

Diseases May be affected by a rust

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