Persicaria virginiana

RHS Plant Profile
Virginia knotweed

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Synonyms

Polygonum virginianum

Herbaceous Perennial

A species of clump-forming, deciduous herbaceous perennial with heart-shaped, green foliage with a dark brown to dark red 'chevron' across the centre of each leaf. Delicate, wand-like spikes of small pink, red or white flowers appear above the foliage in late summer to autumn. When the mature seedpods are disturbed they are ejected powerfully several feet away from the plant

Position

Full shade

Soil Types

Chalk, Clay, Loam, Sand

Max Height

0.5-1 metres

Max Spread

0.1-0.5 metres

Size

Time to Maturity
2–5 years
Max Spread
0.1-0.5 metres
Max Height
0.5-1 metres

Growing Conditions

Chalk Clay Loam Sand
Moisture
Moist but well–drained
pH
Acid or Alkaline or Neutral

Position

Full shade
Aspect
East–facing or North–facing
Exposure
Exposed or Sheltered
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)
H6

Colour & Scent

Season Stem Flower Foliage Fruit
Spring
Summer
Autumn
Winter

Botanical Details

Family
Polygonaceae
Native to GB/Ireland
No
Foliage
Deciduous
Habit
Clump forming
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
Name Status
Correct
Plant Range
Japan

How to Grow

Cultivation

Grow in moist soil in sun or partial shade

Propagation

Propagate by division in spring or autumn

Suggested planting locations and garden types

  • City and courtyard gardens
  • Cottage and informal garden
  • Flower borders and beds

Pruning

No pruning required. Cut back to ground level in autumn as foliage dies back

Pests

Generally pest-free but may be susceptible to slugs and snails

Diseases

Generally disease-free