What to Do in the Garden in October: A Canadian To-Do List

October isn’t the end of the gardening season. It’s the start of a delicious tasting one.

Across much of Canada, summer tomatoes are done, but a cedar planter doesn’t have to sit empty. Established cool-season crops like kale, carrots, and beets hold well through frost, and cold nights actually make them sweeter, because the plants convert starches into sugars that act as a natural antifreeze. October is also when you plant for next year: garlic and overwintering spinach go in now for some of the earliest harvests of spring.

Your October Cedar Planter To-Do List (Canadian Edition)

1. Clear out spent summer plants and prep your soil
2. Check your first frost date and protect your crops
3. Plant for spring
4. Harvest smart and get ready for winter

1. Clear out spent summer plants and prep your soil

Pull tomato, pepper, squash, and bean plants once they stop producing. In much of Canada, frost has already began to finish them off. Before they go, pick any last peppers and green tomatoes. 

Compost healthy plant material, but bag anything diseased, like tomato leaves blackened by blight. Most backyard compost piles don’t get hot enough to kill disease spores, so they can return next year.

Loosen the soil and mix in 3 to 5 cm of compost or shredded fall leaves, which are free in just about every Canadian yard this month. Running leaves over with the lawnmower first helps them break down faster. Skip fertilizer now, since plants can’t use it this late in the season.

Then plant garlic. Mid-October is prime garlic-planting time across most of Canada, ideally a few weeks before the ground freezes. Plant cloves pointy end up, about 5 cm deep and 15 cm apart, and cover the bed with straw once the soil starts to freeze. Use seed garlic from a garden centre or local grower, since grocery store bulbs are often treated to prevent sprouting. You’ll be harvesting next July.

2. Check your first frost date and protect your crops

Look up your average first frost date by postal code, and find your zone on Natural Resources Canada’s plant hardiness zone map. Frost timing varies a lot across the country. The Prairies and the North often see it in early September; southern Ontario, Quebec, and the Maritimes usually get it between late September and mid-October; and coastal BC can stay frost-free into November.

It helps to know the difference between a light and a hard frost. A light frost, around 0 to -2°C, damages tender plants like basil and tomatoes but barely bothers cool-season crops. A hard frost, below about -3°C for several hours, finishes off most annuals, though kale and carrots can handle much colder.

To protect what’s still in your planter, cover it with a frost cloth or old bedsheet in the late afternoon to trap the day’s warmth, and weigh down the edges so fall winds don’t carry it off. Remove it the next morning once temperatures climb above freezing. Watering the day before a cold night helps too, since moist soil holds heat better than dry soil.

3. Plant for spring

By mid-October, growth has nearly stopped across most of Canada. Cold soil and shrinking daylight mean new seeds won’t mature before winter, so this month’s planting is really about next year.

Garlic is the big one, but spinach is a close second. Sown just before the ground freezes, it will often sit dormant over winter and sprout as soon as the snow melts, giving you fresh greens weeks before spring-sown crops. Hardy varieties like Bloomsdale work best. Some gardeners also try this dormant seeding technique with lettuce, arugula, and kale. Results vary, but it’s an easy experiment if you have empty space.

If kale, chard, carrots, beets, or leeks are already planted, let them stay. They won’t grow much more, but your planter works like a cold-storage cellar. Kale can handle temperatures around -10°C, and carrots can stay in the soil under a thick layer of mulch and be dug up as needed into early winter. Chard and beets are less hardy, so harvest them before temperatures dip much below -3°C.

Hardy herbs like thyme, chives, and oregano will come back next spring, and parsley often lasts well into winter. Rosemary and basil won’t survive outdoors, so harvest them now or pot them up for a sunny windowsill.

Gardeners in coastal BC are the exception. With mild temperatures into November, you can still get a quick crop of arugula or baby spinach from an October sowing, especially under a greenhouse cover.

4. Harvest smart and get ready for winter

Pick greens leaf by leaf from the outside of the plant so the centre stays healthy, and on frosty mornings, wait until plants thaw before harvesting, since frozen leaves bruise easily. Trim root crop tops to about 2 cm before storing so the roots stay firm in the fridge.

Once your last crops are harvested, cover the soil with shredded leaves or straw instead of leaving it bare. Raised beds freeze sooner than in-ground beds because their sides are exposed, so a thick layer of mulch is especially helpful for overwintering garlic and spinach.

Our planters are built from WRCLA-certified Western Red Cedar, which naturally resists rot and moisture without chemical treatment, they can handle freeze-thaw cycles and snow cover and be ready to go again in spring.

FAQ

Is it too late to plant garlic in October?
Not at all. Mid-October is ideal across most of Canada. Aim to plant two to four weeks before the ground freezes so the cloves have time to grow roots before winter. In colder regions like the Prairies and northern Ontario, early October is safer, while coastal BC gardeners can plant into November.

Can I leave my raised bed empty over winter?
You can, but it’s better to cover the soil with 5 to 10 cm of shredded leaves or straw. Bare soil can compact, erode, and lose nutrients over the winter, while a layer of mulch protects it and breaks down into organic matter for next season. 

Which vegetables can stay in the garden after the first frost?
Kale, carrots, leeks, and parsnips are the hardiest and can stay in the ground through several hard frosts. Kale and carrots even taste sweeter afterward. Chard, beets, and spinach handle light frosts but should be harvested before temperatures fall much below -3°C, unless you’re overwintering spinach for spring.