Invasive knotweeds (Fallopia ssp./Polygonum ssp.)
Invasive knotweeds (Fallopia spp./Polygonum ssp.)

Invasive Knotweeds

Management Options


  • Native to eastern Asia (Japan, China, Korea).
  • There are three varieties of knotweed (Fallopia spp., Polygonum ssp.) present in our region: Japanese, Giant and Bohemian knotweed, all have similar characteristics and concerns.
  • Herbaceous perennial.
  • Hollow stems, similar in appearance to bamboo.
  • Reach 3-4 m high.
  • May have small cream, white or slightly pink flowers.
  • Reproduces vegetatively.
  • Adapted to moist conditions, generally shade tolerant.
  • Found throughout the region, along roadsides primarily.

Introduction and Spread

  • Knotweed was initially introduced to BC for ornamental use, especially for privacy purposes as it grows rapidly and forms dense patches.
  • The plant reproduces through fragmentation, so when small pieces of the plant are moved by mowers, equipment or other vectors it can allow the plant to spread.

Consequences of invasion

  • Invades roadsides, disturbed sites, wetlands, riparian areas and streambanks.
  • Increases erosion and sedimentation of streambanks and riparian areas.
  • Decreases fish habitat and has negative impacts on salmonids.
  • Negatively impacts infrastructure such as asphalt and house foundations by growing through them.
  • May decrease property value.

Reporting Sightings

If you see this plant, please report it using the provincial reporting tools or send an email to Please include the following details: date observed, precise location, photos, and the size of the infestation.

Additional Resources:

Knotweeds | ISCBC

Knotweed Brochure with list of Herbicide Contractors

CKISS Plant Profile

ISCMV Knotweed Best Mangement Practices