Garden Pests: WEEDS

By Joan Neiman-Agapas, Master Gardener, SCMG.

One wise garden pundit described a weed ‘as a plant whose merits have yet to be discovered’.

The Canadian Oxford Dictionary defines a weed as  ‘a wild plant growing where it is not wanted’.

Regardless, weeds are the biggest headache for many gardeners.

The better you know and can identify your enemy, the easier it is to eradicate them.

The link below takes you to a list of noxious weeds in Ontario:

Traditionally, ‘noxious weed’ is a legal term for any invasive, non-native plant that threatens agricultural crops, local eco systems or fish or wildlife habitat. They include non-native grasses, flowering plants, shrubs, trees & aquatic plants that invade wetlands, rivers, lakes & shorelines.

The three types of weeds are:

1.Annual: a plant which completes its life within one growing season (chickweed, lambs quarters)

2.Biennial: a plant which takes two years to complete its life cycle (bull thistle, garlic mustard)

3.Perennial: a plant which lasts more than two years by growing and blooming over the growing season, then going through a period of dormancy over the winter, and returning in spring from their rootstock (dandelions, purple loosestrife)

Control consists of:

1.Culturali.e. close planting, cover crops, mulching

2.Mechanicali.e. hand pulling, hoeing, digging & mowing

3.Chemicali.e. herbicides to target growth and spread (option of last resort)


Gallery of Most Wanted

Giant Hogweed Heracleum mantegazzianum (pictured above)

  • Member of the Carrot family
  • Originally imported from southwestern Asia as an ornamental
  • Spreads rapidly & grows alongside roadside, ditches & streams
  • Produces thousands of seeds which can remain viable in the soil up to 15 years
  • Clear, watery sap contains toxins that cause severe dermatitis.
  • Severe burns occur if affected skin is exposed to sunlight
  • If spotted, call Invading Species Hotline 1-800-563-7711 or visit EDDMaps to report a sighting
  • Removal should be conducted by a professional