• Miscellaneous

Ragweed is an invasive plant and one of the primary causes of seasonal allergic rhinitis in Quebec. According to statistics from the Ministère de la Santé et des Services sociaux du Québec (MSSS), ragweed is responsible for 75% of pollen allergies and affects one in eight Quebecers . Following several residents’ calls on the subject, the Green Line wants to educate citizens on the plant’s harmful effects and help to identify ragweed so that we can better control it.

Identifying ragweed
There are two types of ragweed: giant ragweed (Ambrosia trifida) and common ragweed (Ambrosia artemisiifolia).

  • Ragweed can be recognized by its jagged, oppositely oriented leaflets, similar to those on carrots.
  • Ragweed pollen is responsible for hay fever and seasonal rhinitis, but is not dangerous to touch .
  • Giant ragweed grows along streets, sidewalks, and vacant lots.
  • Common ragweed grows in neglected lawns and grassy land where the soil has low organic matter levels.
  • Ragweed is an annual plant  that reproduces by seeds. Its flowering season lasts from mid-July until fall. Its pollen is very light and easily carried by the wind.

It is important to intervene before flowering to prevent the plant from propagating. According to a recent study, the Ministre de la Santé et des Services sociaux du Québec recommends cutting twice a year to control the plant, once in July and once in August. 
Our recommendations for limiting the presence of ragweed

  • Do not let the plant flower (its flowering season lasts from mid-July to mid-August).
  • Use mulch or ground cover in places where there is no lawn.
  • Improve the quality of the soil by enriching it with organic matter (compost and natural fertilizers).
  • Sow other plants such as clover and bluegrass, as ragweed has a hard time contending with competition. This practice will help limit its growth.

It is important to remember that ragweed does not thrive in soil rich in organic matter or in well-maintained lawns. We wish to improve the Town of Mount Royal’s environment so that we can all enjoy the summer. The Parks and Green Spaces Department is doing its part by mowing and cutting at specific times to control this plant. The Green Line is your resource for lawn care and landscaping tips and tricks.


Green Line

Technical Coordinator - Environment

180 Clyde Road

Mount Royal H3P 3J9