Canadian Thistle

Canada Thistle is a herbaceous perennial and one of the most commonly seen thistles due to its ability to spread prolifically. Canada Thistle is found in many different landscapes, and thrives in soils that have been disturbed which include: managed gardens and natural landscapes. Thistle prefers full sun exposure and moist – wet soils, but its deep tap root and rhizomatous horizontal roots allow it to adapt to several different soil types, moisture and light conditions.

Scientific Name: Cirsium arvense

Common Name: Canada Thistle

Type: Invasive Plant, Noxious Weed

Family: Asteraceae

Control Methods

Canada thistle is very hard to control and requires extensive commitment to contain and prevent further spread. Even the smallest pieces of roots can grow new plants. The primary spread of this plant is through its rhizomes spreading laterally. Thistle also creates an abundance of seeds. One Thistle plant can produce 1500 – 5000 seeds, and are commonly dispersed from wind.

In gardens and turf locations the most effective control or removal technique is by hand or with a tool such as trowels or shovels. Make sure to remove as much of the plant as possible to prevent continuous spread. Removing plants before they go to seed will greatly reduce their spread. Herbicides can be used but should be used with great care and precision. Two applications will be most effective, spraying in spring before flowering, and again in fall on any new growth.

Disposal

Canadian Thistle should not be combined with other green waste. Notify the attendant when bringing to green waste facilities to see if they have an area where it can be disposed. For green waste facilities put contents into a clear plastic bag. If there is not a location for it to be disposed, contents can be put into a black plastic bag and put it in your garbage bin or take to your local garbage disposal facility.