What Gardeners Must Know – Halton area Grasp Gardeners

Cathy Kavassalis – Halton Grasp Gardener

August 30, 2025

Canada’s Plant Hardiness Zones Up to date

Pure Assets Canada has launched the primary replace to Canada’s Plant Hardiness Zone Maps in over a decade, based mostly on 1991–2020 local weather information.

Key Info

Canada’s system is completely different from the USDA’s.
- It makes use of 7 local weather variables (see beneath) and never simply minimal winter temperature
  - minimal winter temperatures,
  - size of the frost-free interval,
  - summer time rainfall,
  - most temperatures,
  - snow cowl,
  - January rainfall
  - most wind velocity.

These seven collectively generate a suitability index that’s then divided into hardiness zones (0 to 9, with “a” and “b” subzones).

Since 1961–1990, most of Canada has warmed by ½ to 2 full zones.
99.6% of adjustments have been will increase, although just a few small areas (e.g., components of Newfoundland, Vancouver Island, Prairies, and northern Quebec) noticed decreases.

The most important drivers of change have been:

hotter winters
longer frost-free intervals
hotter summers.

Ontario Highlights

The GTA (Higher Toronto Space) is Zone 7a.
Ottawa has modified solely barely and stays 5a.
Saute St. Marie is Zone 5a.
Windsor is Zone 7b.

👉 Examine your nearest municipality right here

The Canadian plant hardiness zone map for the 1991-2020 local weather interval, with insets exhibiting better element for: (a) southwestern British Columbia, (b) southern Ontario, and (c) the Maritime provinces of Nova Scotia, New Brunswick, and Prince Edward Island.

Gardening Implications

Hotter temperatures and longer seasons might permit for prolonged harvests and for rising a better number of vegetables and fruit, however drought, heavy rains, and false springs imply gardeners will face more and more unpredictable circumstances.

Invasive Species and Warning

Bear in mind that invasive crops, pests and illnesses can have new alternatives to unfold.
Use warning when including new crops, soils, or mulches to your backyard.
At all times examine a plant’s invasive potential earlier than selecting new introductions (kind the botanical identify + “invasive” into your search engine).
Watch out to not transfer invasive species between areas (motion of crops, wooden, soils/mulches, and not directly on boots & autos).