Persicaria microcephala

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small-headed knotweed

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small-headed knotweed RHS
small-headed knotweed RHS / Joanna Kossak
small-headed knotweed RHS / Joanna Kossak
Herbaceous Perennial
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A dense, rhizomatous herbaceous perennial with distinctively-patterned, reddish to dark green oval foliage with distinctive brown and grey markings which are held on short, winged stalks. Small, rounded heads of tiny white or pinkish flowers top branching stems to 60cm high, from midsummer to autumn

Position

Full sun, Partial shade

Soil Types

Chalk, Clay, Loam, Sand

Max Height

0.5-1 metres

Max Spread

1.5-2.5 metres

Size

Time to Maturity
2–5 years
Max Spread
1.5-2.5 metres
Max Height
0.5-1 metres

Growing Conditions

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

Position

Full sun Partial shade
Aspect
West–facing or South–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)
H5

Colour & Scent

Season Stem Flower Foliage Fruit
Spring
Summer
Autumn
Winter

Botanical Details

Family
Polygonaceae
Native to GB/Ireland
No
Foliage
Semi evergreen
Habit
Trailing
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
SE Asia

How to Grow

Cultivation

Grow in well-drained or moisture retentive soil in sun or part-shade. Dense groundcover, but has the potential to become a nuisance if not managed well

Propagation

Propagate by seed in spring, or propagate by stem tip cuttings of non flowering shoots or by division

Suggested planting locations and garden types

  • Cottage and informal garden
  • Coastal
  • Wildflower meadow
  • Banks and slopes
  • Flower borders and beds
  • Ground cover

Pruning

Cut back in autumn

Pests

Generally pest-free

Diseases

Generally disease-free