branch of a green, leavy plant, with heart-shaped leaves in a zigzag pattern along the branch

Invasive Species: Knotweed

Managing invasive knotweed in the City of Terrace

Invasive Species: Knotweed

What is Knotweed?

Knotweed is a highly invasive plant that resembles bamboo. Stems are hollow and often have reddish-brown speckles. Leaves are heart- or triangular-shaped, and they grow in a zigzag pattern along the stems. Flowers are attractive plumes of small white clusters. 


Knotweed is considered one of the world's most invasive plant species and is designated as provincially noxious under the Weed Control Act. Its strong root system can cause significant damage to concrete foundations, buildings, retaining walls, roads, and pipes.

There are four variations of knotweed—Himalayan, giant, Bohemian, and Japanese—all of which are designated as provincially noxious plants under the Weed Control Act.

Chemical control with a systemic herbicide (glyphosate) is the recommended treatment strategy, and it generally takes a few treatment rounds to successfully eliminate the invasive plant. This herbicide works by being absorbed into the plant and has no residual effects. People and pets can safely reenter the sprayed area once the product is dry (or after 12 hours).  


Report Knotweed and Request Treatment

The City of Terrace partners with the Northwest Invasive Plant Council (NWIPC) to identify and manage invasive plant species in our community. As part of the 2024 invasive plant management program, we have decided to focus on eradicating knotweed.

Do you believe knotweed is present on your own property?

We require homeowner permission to allow contracted staff to contact you and schedule an assessment, which will allow us to confirm whether knotweed is present on your property and undertake the treatment if required. If knotweed is observed, the Northwest Invasive Plant Council and its contractors will treat this invasive plant at no charge to homeowners. If you recognize this plant on your property, please report it and sign up for an assessment using the form below.

Do you believe you have seen knotweed somewhere else that isn't your own property?

We want to hear about that, too! Please fill out the form below and let us know.

Report Invasive Knotweed

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