Invasive Plants in Alberta: Horticulture Industry

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What is the problem? | Species to watch out for | What you can do | General principles and resources

Land owners and occupiers are responsible for controlling noxious weeds and destroying prohibited noxious weeds under the Alberta Weed Control Act. Listed plants in the Act cause problems for the environment, health or economy. Know your responsibilities under the Act. Regardless of where plants are located, prevention is always the most effective approach in dealing with invasive plants.
What is the Problem?

Gardeners are always interested in trying new and different plants, especially in Alberta where the climate puts strong limits on what can be grown successfully. Most plants sold in the horticulture industry do not cause problems; however, some garden and landscaping plants escape from cultivation into natural areas or agricultural land, where they can spread and multiply.

Some of these plants have significant effects on agriculture and natural ecosystems. Under the Alberta Weed Control Act, propagating and/or selling prohibited noxious or noxious plants are not permitted. Weed Inspectors across the province do enter and inspect horticulture businesses to ensure these plants are not being sold.

Pale yellow iris (Iris pseudacorus)

Species to Watch Out For

Ornamental species on the prohibited noxious weed list in Alberta:
  • pale yellow iris (Iris pseudacorus)
  • flowering rush (Butomus umbellatus)
  • Himalayan balsam (Impatiens glandulifera)
  • purple loosestrife (Lythrum salicaria)
  • bighead knapweed (Centaurea macrocephala)
  • common buckthorn (Rhamnus cathartica)
  • knotweeds (Fallopia species)
  • tamarisk or salt cedar (Tamarix species)
Ornamental species on the noxious weed list in Alberta:
  • yellow clematis (Clematis tangutica)
  • baby’s breath (Gypsophila paniculata)
  • dame’s rocket (Hesperis matronalis)
  • toadflax (Linaria vulgaris and Linaria dalmatica)
  • ox-eye daisy (Leucanthemum vulgare)
  • common tansy (Tanacetum vulgare)
  • creeping bellflower (Campanula rapunculoides)

Purple loosestrife (Lythrum salicaria)

Himalayan balsam (Impatiens glandulifera)

Bighead knapweed (Centaurea macrocephala)

Tamarisk or salt cedar (Tamarix species)

Common buckthorn (Rhamnus cathartica)

Ox-eye daisy (Leucanthemum vulgare)

What You Can Do
  • Do not sell species on the noxious or prohibited noxious weed list.
  • Land owners and occupiers are responsible for controlling noxious weeds and destroying prohibited noxious weeds. Know your responsibilities under the Alberta Weed Control Act.
  • Recommend non-invasive alternatives if customers ask for invasive species (see “Weed-Wise Gardening” in the Learn More list).
  • Ensure that plants are labelled accurately, with scientific as well as common names.
  • Ensure that bulk materials like topsoil and gravel are from sources free of invasive plants.
  • Dispose of plant waste and surplus stock responsibly.
  • Watch for invasive plant infestations on nursery and garden centre premises and control them if found.
  • Ensure “wild flower” mixes, which are often inaccurately labelled, do not contain invasive plants listed in the Alberta Weed Control Act.
  • Consider expanding the selection of Alberta native plants that you offer.
  • Check with Alberta Agriculture and Rural Development if there are questions about invasiveness or regulatory status of plants.

Flowering rush (Butomus umbellatus)

Baby’s breath (Gypsophila paniculata)

Creeping bellflower (Campanula rapunculoides)

Dame’s rocket (Hesperis matronalis)

Toadflax (Linaria vulgaris and Linaria dalmatica)

Yellow clematis (Clematis tangutica)

Common tansy (Tanacetum vulgare)
General Principles and Resources Learn More

Find out more on this topic and access these additional resources at the following web page: Source: Agdex 640-19. February 2014.
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For more information about the content of this document, contact Chris Neeser.
This document is maintained by Jennifer Rutter.
This information published to the web on February 28, 2014.
Last Reviewed/Revised on August 21, 2018.