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Ragweed and poison ivy

Sneezing, blocked noses and itchy, watery eyes: ragweed allergy sufferers know these symptoms all too well and are affected throughout the season, which starts in August and ends with the first frosts of winter.

But don’t confuse ragweed with poison ivy! When the leaves of this plant come in contact with a person’s skin, they cause immediate itching.

Whether at work, at home, or just out for a walk, keep an eye open for ragweed. Together we can eliminate this nuisance!

Herbe à poux, jeune pousseRagweed

Ragweed is a plant that grows from 10 cm to 1.5 m high with green leaves that resemble those of a carrot. When in bloom, it has yellowish green flowers that grow in clusters. The allergen in ragweed that causes hay fever is its pollen

Its urbain habitat

If you want to eliminate ragweed, you have to know where it grows. It loves to grow in clumps in sunny spots. Ragweed has a preference for badly maintained, poor quality soil such as that found along railway tracks, next to sidewalks, on construction sites, on neglected lots, on patches of bare land, where road salt has killed off a lawn, in a corner of the garden, or where soil has been disturbed.

Herbe à poux, plant à maturitéSymptoms of ragweed allergies

Only individuals who are allergic to ragweed experience symptoms: sneezing, congestion, irritated eyes and throat, etc.

Even if over-the-counter antihistamine pills and decongestants provide some measure of relief to sufferers, this respiratory allergy gives rise to many health problems and carries huge social costs due to medical expenses and work absenteeism.

This problem requires a radical solution: eliminate it at the source—uproot every ragweed plant that you can find!

How to eliminate ragweed?

  • Pull up the plants manually or mow them before they bloom towards the end of July and again around the third week of August.
  • Use mulch to prevent the plant from growing.
  • Improve soil quality (topsoil, fertilizer).
  • Plant seeds or other plants to compete with ragweed.

To prevent a wave of allergies and stop the plants from reproducing, it is recommended that you mow them before they flower, which they usually do around the end of July and the end of August. 

If you see any ragweed growing on City-owned public land, you can notify our environment agent, by email at

Herbe à la pucePoison ivy 

Poison ivy grows from 20 cm to 1 m high and can appear in various forms: bushy, creeping, or climbing. Its shiny foliage is wine red in spring, dark green in summer and multicoloured in the fall. This plant contains a poisonous sap that causes inflammation of the skin, even in winter.

Its urban habitat

Poison ivy grows mostly near wooded areas.

Symptoms caused by poison ivy 

Anyone who has been in contact with the poisonous sap can react to poison ivy. The symptoms are: red skin inflammation, strong itching, and the formation of blisters on the affected areas.

How to eliminate poison ivy?

  • Wear gloves when handling the plant and avoid any contact with the skin.
  • Pull the plant up by the roots.
  • Place dead plants in garbage bags or bury them very deep in the soil.

Never compost or burn poison ivy. Inhaling the smoke from the burning plant material can cause a severe pulmonary reaction.