When to Plant Collard Greens in Ontario
Published: April 24, 2026 · Updated: April 27, 2026
Extremely cold-hardy leafy brassica — withstands temperatures to -10°C. Direct sow or transplant 3–4 weeks before last frost. Fall plantings produce the best-flavored greens after frost.
Collard Greens grow well in this province with appropriate variety selection and standard Canadian planting timing.
Collard Greens Planting Window for Ontario
Start seeds indoors: March 16–23 (varies by city — earliest in southern Ontario, latest on the Prairies)
Transplant outdoors: March 30–April 9 (after last frost in your city)
Direct sow outdoors: March 30–April 9
Minimum soil temperature: 7°C (45°F)
Days to harvest: 60–75 days
Sun requirement: Full sun to partial shade
Fall crop planting: August 23–September 2
⚠ Direct sow or transplant collard greens 3–4 weeks before last frost. Extremely cold hardy — withstands temps to 15°F. Can be grown as a perennial in Zones 8+. Fall planting produces the best-flavored greens.
Ontario Cities — Collard Greens Planting Dates
City-specific frost dates and collard green planting windows for Ontario.
Growing Collard Greens in Ontario
- Harvest outer leaves continuously once plants reach 10 inches — the central growing point produces for months.
- In Zones 8+ collard greens often overwinter and produce for 2–3 years as a perennial.
- Frost improves flavor dramatically — southern tradition is to wait for the first frost before harvesting.
- Blanch and freeze excess harvest — collard greens freeze beautifully and provide winter vitamins.
Companion Planting for Collard Greens
In Ontario gardens, pair collard green with Onion, Garlic, Dill, Celery. Avoid planting near Tomato, Strawberry, Bean, which compete with or inhibit collard green growth.
Common Pests and Problems
Collard Greens in Ontario are commonly affected by Cabbage Worm, Aphid, Flea Beetle, Cabbage Looper. Floating row covers installed at planting block most adult pests from laying eggs, and a weekly scouting routine catches infestations before they damage the crop.
Frequently Asked Questions
When should I plant collard green in Ontario?
In Ontario (Canadian Zones 5b–6b), start seeds indoors around March 16 and transplant around March 30. Collard Greens grow well in this province with appropriate variety selection and standard Canadian planting timing.
What is the best collard green variety for Ontario?
Ontario gardeners should prioritise varieties bred for shorter seasons or Canadian climates. For collard greens in Canadian Zones 5b–6b, look for cultivars labelled under 75 days to maturity. Local nurseries and provincial seed exchanges curate varieties that ripen within Canadian frost-free windows.
How does Ontario's climate affect collard green?
Ontario spans Canadian Zones 5b–6b with frost-free seasons ranging from roughly 153 to 195 days. Collard Greens actually prefer the cooler spring and fall windows typical of Ontario, making them one of the most reliable crops in the province.
Can I grow collard green in containers in Ontario?
Yes. Container growing on balconies and patios extends the viable growing area across every Canadian province. Dark-coloured containers warm up faster in spring and extend the season on both ends. Choose a 5-gallon or larger pot for collard green and water daily during hot summer weather, since containers dry out quickly.
When is the first fall frost in Ontario?
First fall frost dates in Ontario range from October 15 in the coldest areas to November 1 in the warmest. For a fall collard green crop, count back from your local first-frost date and plant around August 23–September 2.