The Ontario garden, month by month.
A plain-English reference library for Zone 5b and 6a — Durham Region and the east GTA — where the clay is heavy, the last frost lands in early May, and the first one closes the season in mid-October. When to plant, how to run a lawn without cosmetic pesticides (they’re banned in Ontario, and the lawn is better for the methods that replace them), and what to do each month so nothing sneaks up on you.
- 7 guides in this first batch
- 5b–6a zones covered
- Early May average last frost
- Mid-Oct average first frost
What to do this month — October
- Plant garlic — cloves in the ground a few weeks before it freezes, mulched with straw. See the fall checklist
- Sow fall rye on any vegetable bed that will sit empty, and plant spring bulbs before the ground hardens.
- Keep mowing until growth stops, finishing around 6 cm, and rake leaves off the lawn into the beds. See the lawn calendar
- Bring in the last tender crops before the first frost — tomatoes ripen indoors on the counter.
- Drain hoses and shut off outdoor taps before the first hard freeze.
Find a guide
Search by topic, plant, problem, or month — try “grubs”, “tomatoes”, “clay”, or “September”.
Showing all 7 guides in the first batch.
The first batch
Seven guides covering the questions Zone 5b/6a gardeners ask most.
frost
Planting dates for the most common vegetables in Zone 5b and 6a — what goes in the ground early, what waits for warm soil, and what has to be started indoors in March if you want a harvest at all.
VegetablesPlan once, plant all seasonAllyear
The whole lawn year on one page for Zone 5b/6a: when to fertilize, overseed, aerate, and dethatch — and the mowing and watering habits that do more for an Ontario lawn than anything in a bag.
LawnA few weekends a yearSepbest
Bare patches, thin spots, and the worn path the dog takes — fixed by overseeding done properly: seed pressed into real soil contact, kept moist for three weeks, at the time of year Ontario weather does half the work for you.
LawnAn afternoon + 3 weeks of wateringAug–Sep
Brown patches that peel up like carpet in late summer usually mean white grubs — beetle larvae eating grass roots just under the surface. How to confirm them, when they actually do damage, and the one treatment window that works in Ontario.
LawnOne application + wateringMarstart
Tomatoes are the crop Ontario gardeners most want and most often plant too early. The Zone 5b/6 playbook: start indoors in March, transplant only after frost risk passes in late May, support them properly, and head off the three problems every Durham tomato grower meets by August.
VegetablesMarch to first frostSoilfirst
Much of Durham Region sits on heavy clay: sticky when wet, brick-hard when dry, and slow to warm in spring. It isn’t bad soil — it’s unfinished soil. This is what actually improves it, season by season, and what’s a waste of money.
SoilImproves every seasonOctlist
The fall cleanup that actually helps: what to cut back and clear in October, what to deliberately leave standing until spring (your garden’s wildlife will thank you), planting garlic, and putting the lawn to bed ready for winter.
SeasonalA weekend or two in OctoberHow every guide is built
One formula, followed the same way on every page.
What & when
The job explained plainly, with the Zone 5b/6a timing that decides whether it works.
Steps, in order
The method in sequence, from prep to finish — nothing skipped, nothing out of order.
Common mistakes
The ways the job usually goes wrong in Ontario conditions, so you can skip them.
Good to know
The one insight that separates gardeners who fight their yard from gardeners who work with it.
The Ontario rules of the game
Every guide on this site works within these facts:
- Cosmetic pesticides are banned. Ontario has prohibited cosmetic herbicides and insecticides on home lawns and gardens since 2009. The methods here — thick overseeded turf, correct mowing height, beneficial nematodes — are the legal playbook, and they work.
- Zones are averages. Zone 5b/6a frost dates (last frost early May, first frost mid-October) describe a typical year in Durham and the east GTA. Your yard’s low spots and fences shift them by days.
- Clay is the default. Most advice here assumes heavy clay soil unless it says otherwise — because around here, it usually is.