Noxious weeds loom in wildflower mixes

LACOMBE, Alta. — An Alberta Agriculture researcher has been growing wildflowers in a greenhouse this winter.

The project is testing commercially available wildflower seed mixes to see if invasive plants or noxious weeds are being distributed to home gardeners.

Weed specialist Nicole Kimmel found almost no problems in the 64 packets she planted late last year. The rest of the 128 packages collected from across Canada will be grown later this spring. 

People assume wildflower mixes are native plants to the local area, but Kimmel told an Alberta Invasive Species Council meeting in Lacombe March 12 that they may also come from New Zealand or China. 

“We are getting things from all over the world,” she said. 

Kimmel is looking for plants such as oxeye daisy, scentless chamomile, common tansy, common baby’s breath and bighead knapweed but has only found one suspect species. 

Many of her plants are the same genus as noxious weeds but turned out to be different species such as Moroccan toadflax rather than yellow toadflax or Chinese forget me not, which is the same plant genus as hounds-tongue.


A similar study at the University of Washington also grew seed packages to see what they contained.

Individual packages contained three to 13 invasive species, and eight were considered noxious weeds. A third had unlisted products and inaccurate listings.

In Canada, provincial and federal authorities can halt the sale of wildflower packages.

“The Weed Control Act does have authority. We do have the authority to pull things off the shelves if we knew they were harbouring prohibited or noxious species,” Kimmel said.

“The contents list is not always accurate.” 

Any seed that is a specialty seed must be labelled under federal law.


“It is just not happening,” she said. 

The Canadian Food Inspection Agency and the Canadian Border Services Agency try to keep the flowers out, but 500 gram shipments of small seeds or five kilograms of large seeds are not checked. 

The law was written to allow for small imports of seed, which were thought to be headed for research, but wildflower mixes may also arrive in small amounts. 

Many jurisdictions offer programs to home gardeners to help them make the right selections when buying seeds or plants. 

The council also developed a You-Tube video about garden invaders.

For a list of plants to avoid and tips on weed wise gardening, visit