• AGM plants

    AGM plants have been through a rigourous 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 bistorta 'Superba'

Red bistort 'Superba'

AGM plants

AGM plants have been through a rigourous 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
Red bistort 'Superba'

© � RHS

  • Other common names Red bistort 'Superba'

  • Synonyms Polygonum bistorta 'Superbum'

  • 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

  • Family Polygonaceae / Polygonaceae

  • Species 'Superba' is a vigorous clump-forming herbaceous or semi-evergreen perennial to 90cm in height, with strongly veined, finely pointed ovate leaves and dense spikes of small light pink flowers

Characteristics

  • Foliage Semi-evergreen

  • 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)
    Old hardiness ratings

    While we update our systems with the new hardiness ratings you may still see old hardiness ratings in your search results. These are denoted as 'Old'.

    • H1 - Requires heated glass
    • H2 - Requires unheated glass
    • H3 - Hardy outside in some regions of the UK
    • H4 - Hardy throughout the UK
    • H1 + H3 - Requires heated glass but may be grown outside in summer

    For full details of the hardiness ratings see

    see more

    H7

Colour

Sunlight

  • Full Sun

  • Partial Shade

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

  • Exposure Exposed or Sheltered

Soil

  • Chalk

    Clay

  • Chalk

    Loam

  • Chalk

    Sand

  • Chalk

    Chalk

  • MoistureMoist but well-drained, Poorly-drained

  • SoilClay, Loam, Sand, Chalk

  • pHAlkaline, Neutral, Acid

Size

  • Ultimate height

    0.5-1 metres

  • Ultimate spread

    0.5-1 metres

  • Time to ultimate height

    2-5 years

How to grow

Cultivation Ideal for a moist soil although it can tolerate some dryness; copes in full sun or partial shade

Propagation Propagate by division in spring or autumn

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

How to care

Pruning Deadhead faded spikes

Pests Generally pest free

Diseases Generally disease free

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