There are a number of invasive plant species in the Central Kootenay.
Download our most recent priority list here (PDF - 44KB)

For more detailed information on the biology, distribution, and management strategy for each species in our region, please see the Invasive Plant Profiles

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Japanese and giant knotweed

Japanese knotweed (Fallopia cuspidatum) and giant knotweed (P. sachalinese) are tall shrubs with bamboo-like stems. They have been planted throughout the Central Kootenay as garden ornamentals but they quickly spread to form dense thickets in a variety of habitats, including dry roadsides and moist stream banks. Small patches can quickly spread into large areas, leaving little room for native species to grow.

Concern over knotweed has been mounting around the world as more and more native habitat is being lost, particularly in riparian areas. Knotweed is listed as a noxious weed in many parts of North America and should not be planted or cultivated. Japanese knotweed is considered to be the most pernicious weed in England! For more information on the breadth of this problem, see the Japanese Knotweed Alliance website.

These plants can be identified because they are tall (can grow more than 3 m), Giant knotweed has extremely large heart-shaped leaves, while Japanese knotweed has smaller leaves that are flat at the base with a pointed tip. Both plants have small white flowers that bloom in late summer.

As a resident, you can help control the spread of these invasive species by removing them from your property. Small plants can be dug up, being careful to remove all plant parts. Large patches should be cut down and covered with thick plastic to prevent re-sprouting. Avoid spreading cuttings or vegetative pieces of the plants through garden waste, dumping, or vehicles. Experiments are currently being conducted on the coast with overwatering plants with salt water to control them.


Additional Information:
www.nwcb.wa.gov/weed_info/Written_f ...

Invasive Plant Profile:
Knotweeds - Polygonum spp. - 670.4 KB

Return to Local Weeds to Watch For