When to Plant Lettuce in Ontario
Published: April 24, 2026 · Updated: April 27, 2026
The fastest cool-season crop — some varieties ready in 30 days. Lettuce must be timed to cool seasons as it bolts (goes to seed and turns bitter) in summer heat.
Lettuce grow well in this province with appropriate variety selection and standard Canadian planting timing.
Lettuce Planting Window for Ontario
Start seeds indoors: March 23–30 (varies by city — earliest in southern Ontario, latest on the Prairies)
Transplant outdoors: March 23–April 2 (after last frost in your city)
Direct sow outdoors: March 9–19
Minimum soil temperature: 4°C (40°F)
Days to harvest: 30–60 days
Sun requirement: Full sun to partial shade
Fall crop planting: September 20–30
Ontario Cities — Lettuce Planting Dates
City-specific frost dates and lettuce planting windows for Ontario.
Growing Lettuce in Ontario
- Direct sow very shallowly — lettuce seeds need light to germinate; cover with just 1/8 inch of soil.
- Cut outer leaves 1 inch above the crown for "cut-and-come-again" harvests lasting weeks.
- Provide afternoon shade in warmer climates (Zones 7+) to extend the spring window before heat bolts plants.
- Fall lettuce is often better than spring — plants mature as temperatures cool, producing sweeter, crunchier heads.
Companion Planting for Lettuce
In Ontario gardens, pair lettuce with Carrot, Radish, Strawberry, Chive. Avoid planting near Fennel, Celery, which compete with or inhibit lettuce growth.
Common Pests and Problems
Lettuce in Ontario are commonly affected by Aphids, Slugs, Cutworm, Leaf Miner. 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 lettuce in Ontario?
In Ontario (Canadian Zones 5b–6b), start seeds indoors around March 23 and transplant around March 23. Lettuce grow well in this province with appropriate variety selection and standard Canadian planting timing.
What is the best lettuce variety for Ontario?
Ontario gardeners should prioritise varieties bred for shorter seasons or Canadian climates. For lettuce in Canadian Zones 5b–6b, look for cultivars labelled under 60 days to maturity. Local nurseries and provincial seed exchanges curate varieties that ripen within Canadian frost-free windows.
How does Ontario's climate affect lettuce?
Ontario spans Canadian Zones 5b–6b with frost-free seasons ranging from roughly 153 to 195 days. Lettuce 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 lettuce 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 lettuce 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 lettuce crop, count back from your local first-frost date and plant around September 20–30.