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A picture of a Knotweed

Knotweed

Persicaria spp.

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Also known as

Smartweed

Full Sun
Easy care
Moderate watering
Frost Hardy

H7-H4

RHS hardiness

-20°C

Minimum temperature

Expected size

Height
Spread

1.2m

Max

1.2m

25cm

Min

60cm

Flowering

  • spring
  • summer
  • autumn
  • winter

More images

A photo of Knotweed
A photo of Knotweed
Persicaria glabra in Narshapur forest, AP W IMG 1109
Polygonum persicaria
A photo of Knotweed

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Overview

Persicaria - known also as Knotweed or Smartweed - is a genus of mainly annual, semi-evergreen, evergreen or herbaceous perennials that originate from a wide range of habitats worldwide. Knotweeds typically have simple leaves and long-lasting spikes of small bell-like - usually pink or white - flowers. Some species are cultivated as creeping ground cover and some for their autumn leaf colour. Some species however, can become invasive. Persicarias like moist soil and are happy in full sun or partial shade. Popular in borders and rock gardens, there is a species for almost every garden situation.

Common problems

Propagation

Division

Seed

Special Features

Attractive flowers

Autumn colour

Ground cover