Gardening in Ontario

Everything we have worked out for Ontario: what to plant and when, which varieties finish in time, the pests that actually turn up here, and the jobs that pay off month by month. We also cover the rest of the property, from lawns and soil to home care and energy, because a garden rarely stops at the vegetable bed.

The numbers first, because everything else follows from them. Measured at the weather station in Toronto, the last spring freeze falls around April 30 and the first fall freeze falls around October 16, 2,297 growing degree days in the year.

That is enough for early varieties, tight for anything late. Garlic does well: 30.4 weeks below 40 °F, comfortably past the six it needs to form a proper head.

Elsewhere on the property in Ontario: the pests that turn up here.

Figures from Environment and Climate Change Canada. A state is not one climate: elevation, a large lake or the coast can move these dates by two weeks either way, so check your own county with the extension service before you spend money.

What Eats Onion in Ontario, and When

Several freshly harvested onions in various colors arranged on weathered wooden boards with a golden agricultural field in the background.

Onion maggot is the pest that actually goes after onions in Ontario, and it does its worst damage in the first few weeks after seedlings or sets go into…

What Eats Potato in Ontario, and When

A striped Ontario potato beetle perches on a green potato plant leaf in a cultivated field during summer.

The short list that actually feeds on potato in Ontario gardens runs to about a dozen species, not the two dozen a broader vegetable-pest sheet might…

When to Overseed a Lawn in Ontario

Weeds sprouting along a concrete edge in a lawn area during warm season.

The short answer: aim for the first three weeks of September across most of Southern Ontario, working backward from the province’s average first fall…