• 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

Persicaria microcephala 'Red Dragon' (PBR)

knotweed 'Red Dragon'

knotweed 'Red Dragon'

© RHS

  • Other common names knotweed 'Red Dragon'

  • Family Polygonaceae

  • Genus Persicaria can be annuals, herbaceous or evergreen perennials or sub-shrubs with simple leaves and small bell-shaped white or pink flowers in long-lasting spikes or panicles

  • Details 'Red Dragon' is a vigorous, spreading perennial with lance-shaped, purplish-green leaves with a bold central splash of purple bordered by a silver chevron marking, and rounded clusters of tiny white flowers in late summer and autumn

Characteristics

  • Foliage Semi-evergreen

  • Habit Trailing

  • 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

  • Partial Shade

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

  • Exposure Exposed or Sheltered

Soil

  • Loam

    Loam

  • Sand

    Sand

  • Chalk

    Chalk

  • MoistureMoist but well-drained

  • SoilLoam, Sand, Chalk

  • pHAcid, Alkaline, Neutral

Size

  • Ultimate height 0.1-0.5 metres

  • Ultimate spread 0.5-1 metres

  • Time to ultimate height 2-5 years

How to grow

Cultivation Grow in moist soil in sun or part-shade. Dense groundcover, spreading less quickly than the species

Propagation Propagate by stem tip cuttings or by division

Suggested planting locations and garden types Banks and Slopes Flower borders and beds Ground Cover Coastal Cottage & Informal Garden

How to care

Pruning Cut back in autumn

Pests Usually trouble free

Diseases Usually trouble free

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