A Homeowners guide to defending their property from Knotweed invasion.
The Coastal ISC has partnered with other regional weed committees throughout BC to bring you these fun and educational resources to help you defend your property from Knotweed. Visit the website which is full of videos, tips and a downloadable Booklet.
Learn more about:
- Identification
- Property Values and Legal Issues
- What Knot to Do
- Knot Anymore
- Watch Video
- Download the PDF Booklet
Invasive Knotweeds: Japanese, Giant, Bohemian & Himalayan
(Fallopia japonica, Fallopia sachalinensis, Fallopia x bohemica & Polygonum polystachum)
Knotweed Species are found throughout communities on Vancouver Island, the Gulf Islands and the Sunshine Coast.
These non-native, invasive species are listed by the World Conservation Union as one of the world’s worst invasive species.
The invasive root system and strong growth can damage concrete foundations, buildings, septic systems, roads, paving, retaining walls and the environment.
Knotweed can easily take hold in riparian ecosystems, roadsides and waste places. It forms thick, dense colonies that completely crowd out all other plants. The success of the species has been partially attributed to its tolerance of a very wide range of soil types, pH and salinity. Its rhizomes can extend 7 metres (23 ft) horizontally and 3 metres (9.8 ft) deep, making removal by excavation extremely difficult. Additionally even tiny root fragments can regrow into new plants.
The plant is also resilient to cutting, vigorously resprouting from the roots.
The Invasive Species Council of BC in conjunction with the BC Government has stated that the “Chemical control with a systemic herbicide is the recommended treatment strategy for knotweeds due to their extensive root structure and aggressive growth and reproduction. This treatment method is the easiest, most cost effective, and successful treatment method.” In order to remove established patches of Knoweeds, they “typically require treatment with herbicide for 3-5 years” BC Invasives.
For more information on Knotweed, see our page on Japanese Knotweed.
Do you live in Central Vancouver Island or the Comox Valley and want us to remove your Knotweed?
The removal of Knotweed and Giant Hogweed from private land is free to most property owners in the Comox Valley and Central Island* (See below for list of participating locations). Please fill out our Release of Liability for Access and Herbicide Use Agreement Form for the removal of Knotweed or Giant Hogweed from your property.
This permission form adds you to Coastal ISC’s treatment list. It allows Coastal ISC staff to contact you and set up a suitable date to go to your property to monitor and remove the Knotweed or Giant Hogweed species either manually or with a herbicide.
*Participating locations include: Comox, Cumberland, Courtenay, Comox Valley Regional District, Qualicum Beach, Parksville, and the Regional District of Nanaimo (this list is subject to change). Contact us if you want to know more.
Additional Resources:
Invasive Species Council of BC Knotweed
Knotweed Information Sheet – Nanaimo Region
Knotweed Information Sheet – Comox Valley Regional District
Japanese Knotweed: Invasive Plant of Southwestern BC
Want more detailed info?
Understanding & Controlling Invasive Knotweeds in BC by Jeff Hallworth
King County, USA, Best Management Practices for Knotweed
Summary Findings from Knotweed Workshop Held March 2015
“Key to Identification of Invasive Knotweeds in British Columbia” (2007). BC Ministry of FLNRO
