Ontario Planting Calendar 2026 — Month by Month

It depends where in Ontario you are, and the gap is bigger than most people expect. Toronto has an average last frost of April 20, while Sudbury waits until May 31 — a spread of 41 days across one province. Cold-hardy crops such as peas, spinach, lettuce and onions go out two to four weeks before that date. Tender crops — tomatoes, peppers, cucumbers, beans, squash — wait until after it. Find your own city in the table on this page rather than using a single provincial date.

In southern Ontario, April is when cold-hardy crops go outside: peas, spinach, lettuce, radishes, arugula, onion sets and potatoes all tolerate light frost and prefer the cool soil. Windsor, Toronto and Mississauga reach their average last frost around April 20 to April 20, so late April is also when the first tender transplants can be hardened off. In eastern and northern Ontario — Ottawa, Barrie, Sudbury, Thunder Bay — April is still an indoor month, with outdoor sowing starting in May.

May is the main planting month across the whole province. Southern Ontario plants tomatoes, peppers, cucumbers, zucchini, beans and corn from mid-May once the soil has warmed past 15 °C. Ottawa and Kingston plant tender crops after roughly May 9. Northern Ontario — Sudbury and Thunder Bay — should hold tender crops until the very end of May or the first days of June, and use black plastic or row cover to warm the soil first.

Count backwards from your own last frost date, not from a provincial average. Tomatoes need 6 weeks indoors, peppers and eggplant 8, onions and leeks 12, brassicas 6. For Toronto, with a last frost of April 20, that puts onions in late January, peppers in late February and tomatoes in early March. Northern Ontario shifts every one of those dates about 6 weeks later.

Between 109 and 195 frost-free days, depending where you are. Toronto averages 195 days between last spring frost and first fall frost; Sudbury averages 109. That difference decides which varieties are realistic: a 100-day corn or winter squash is comfortable in the southwest and a gamble in the north, where short-season varieties under 80 days are the safer choice.

Toronto's average last spring frost is April 20 and its average first fall frost is November 1, giving about 195 frost-free days in hardiness zone 6b. These are averages from Environment and Climate Change Canada climate normals, which means roughly half of years see a later frost — waiting a week past the date, or keeping frost cover to hand, is the standard insurance.

Garlic is the one crop on this calendar planted in autumn rather than spring. Across Ontario the window is after the first fall frost but before the ground freezes hard — roughly early to mid-October in the south and late September in the north. Plant cloves 5–8 cm deep, pointed end up, and mulch with 10–15 cm of straw. Harvest the following July when the lower three or four leaves have browned.

Plenty, if you plant backwards from the first fall frost rather than forwards from spring. Fast cool-season crops — lettuce, spinach, arugula, radishes, and baby-leaf greens at 25 to 45 days — can be sown into August across southern Ontario. Carrots and beets sown in early July mature for an autumn harvest and taste sweeter after a light frost. The limit is your own first frost date: Toronto has until November 1, but Sudbury only until September 17.