Bistorta affinis

RHS Plant Profile
lesser knotweed

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lesser knotweed RHS

Other common names

East Indian knotweed

Synonyms

Persicaria affinis
Polygonum affine

Herbaceous Perennial
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A mat-forming herbaceous perennial about 25cm high with elliptic to lance-shaped dark green leaves, 5-15cm long, which turn red-bronze in autumn, and from midsummer to mid-autumn spikes 5-8cm long of flowers, each 5mm long, which open bright reddish pink, fade to pale pink, and then turn brown during winter; it is an excellent ground-cover plant

Position

Full sun, Partial shade

Soil Types

Chalk, Clay, Loam, Sand

Max Height

0.1-0.5 metres

Max Spread

0.5-1 metres

Size

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

Growing Conditions

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

Position

Full sun Partial shade
Aspect
South–facing or North–facing or West–facing or East–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)
H7

Colour & Scent

Season Stem Flower Foliage Fruit
Spring
Summer
Autumn
Winter

Botanical Details

Family
Polygonaceae
Native to GB/Ireland
No
Foliage
Evergreen
Habit
Matforming
Genus
A genus of herbaceous, rhizomatous perennials with erect, unbranched stems, bearing short terminal spikes of small, white or pink, bell-shaped flowers
Name Status
Correct
Plant Range
Himalaya

How to Grow

Cultivation

Grow in moist but well-drained soil in sun or partial shade

Propagation

Propagate by seed, sown in containers in a cold frame in spring, or by division in spring or autumn

Suggested planting locations and garden types

  • City and courtyard gardens
  • Cottage and informal garden
  • Low Maintenance
  • Flower borders and beds
  • Garden edging
  • Underplanting of roses and shrubs
  • Banks and slopes
  • Ground cover

Pruning

No pruning required

Pests

Generally pest-free

Diseases

Generally disease-free