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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Scotch thistle

Scotch thistle (Onopordum acanthium) is an introduced garden ornamental that can be impressive when it grows to three meters tall, towering above a gardener. However, since each plant can produce thousands of seeds that are viable in the soil of over 30 years, and plants can "hop" the garden fence into native habitat, this species is highly invasive. In the Okanagan, the detrimental effects of Scotch thistle are being seen since this species has escaped gardens and is impacting wildlife, livestock, and field crops. Since scotch thistle is growing in gardens in the West Kootenays, there is concern that it could do the same here.

Scotch thistle is a tall thistle with multiple flower heads, each growing to five centimeters wide. The leaves are very large and irregularly lobed with sharp yellow spikes along the edges. Upper and lower leaf surfaces are covered with a thick mat of cotton-like or woolly hairs, giving the foliage a grey-green colour.

A small cluster of plants can either spread immediately or over many years. Because the seeds remain viable in the soil so many years, patches in your garden may already harbour a large seed bank below them.

As a resident, you can help control the spread of this invasive species by removing all plants from your property. Plants can cut and then dug up but since they can re-grow from severed roots, care must be taken to remove all plant parts. Avoid spreading cuttings or seeds of the plants through garden waste, dumping, or vehicles. For other control options, see this info sheet from Weeds BC.


Additional Information:
www.agf.gov.bc.ca/cropprot/weedguid ...

Invasive Plant Profile:
Scotch thistle - Onopordum acanthium - 681.6 KB

Return to Local Weeds to Watch For