August Planting Guide for Canada

August feels like summer's peak, but experienced Canadian gardeners know it is actually prime time to plant for fall. Working backwards from your first expected frost date, August is the last window to get quick-maturing crops in the ground and still harvest before the season closes.

This guide covers exactly what to plant in August by hardiness zone — from zone 2 on the Prairies to zone 8 in Victoria, BC.

Why August Planting Matters

In most of Canada, the first fall frost arrives between early September (zone 3) and late October (zone 6–7). That gives August-planted crops 6–10 weeks to mature — enough time for dozens of fast-maturing vegetables.

The key is matching the crop's days to maturity against your remaining frost-free days. Use mygardenplanner.ca's planting date calculator to find your first frost date and calculate exactly what still has time to grow.

What to Plant in August by Zone

Zone 2–3 (Northern Canada, Northern Prairies)

First frost: mid-August to early September — your window is almost closed.

• Radishes (22–30 days): Your best bet. Sow now and harvest before frost.
• Spinach (35–45 days): Direct sow immediately — frost-tolerant and will finish before hard freeze.
• Arugula (35–40 days): Fast, peppery, and handles light frost well.
• Green onions from sets (30–40 days): Quick return if planted immediately.

Zone 2–3 gardeners should focus entirely on short-season, frost-hardy varieties. Skip heat-lovers like beans or cucumbers — there is not enough time.

Zone 4 (Northern Ontario, Northern BC Interior, Yukon Valleys)

First frost: mid to late September. You have 6–8 weeks.

Everything from zone 2–3 plus:

• Kale (50–60 days): Plant transplants now, or direct sow if you have at least 55 days. Frost makes kale sweeter.
• Swiss chard (50–60 days): Handles light frost and delivers great late-season greens.
• Beets (50–60 days for roots, 30 days for greens): Sow now for baby beets or beet greens.
• Turnips (35–60 days): Fast-maturing and underrated as a fall crop.
• Mâche (corn salad) (40–60 days): Cold-hardy and excellent for cool-season salads.

Zone 5 (Southern Ontario, Southern Quebec, Okanagan Valley)

First frost: early to mid-October. You have 8–10 weeks.

Everything from zones above plus:

• Bush beans (50–60 days): Last call — plant no later than mid-August.
• Peas (55–70 days): Cool-season crop that thrives in fall temperatures. Snow peas and snap peas work well.
• Broccoli and cabbage transplants (55–80 days from transplant): Time enough if starting from established seedlings, not seed.
• Lettuce and mixed greens (30–45 days): Excellent fall crop — summer heat is fading and lettuce will not bolt.
• Carrots (60–80 days): Sow immediately for small-to-medium roots. Leave in the ground through light frost for improved sweetness.

Zone 6 (Southern Ontario, BC Fraser Valley)

First frost: late October to early November. You have 10–12 weeks.

Everything from zones above plus:

• Kohlrabi (45–60 days): Underused and fast. Excellent for fall harvest.
• Bok choy and Asian greens (30–60 days): Thrives in cooling fall temperatures.
• Fall broccoli and cauliflower from seed (60–80 days): Still possible if sown in the first week of August.
• Second succession of zucchini (50–60 days): Plant early August for a fresh flush before frost.

Zone 7–8 (Greater Vancouver, Victoria, Gulf Islands)

First frost: November or later. You have 12–16 weeks.

The Pacific Coast is in a category of its own. August is prime time for fall and winter garden setup:

• All brassicas: Broccoli, cauliflower, Brussels sprouts, kale, cabbage — plant now for October–November harvest.
• Garlic: In zone 8, garlic can be planted late August to early September for an early-summer harvest.
• Leeks (100–120 days): Still achievable if planted in early August.
• Winter squash (80–100 days): Last call for zone 7–8 only.
• Cover crops: Fava beans and winter rye fix nitrogen and protect soil through the mild coastal winter.

Succession Planting in August

If you planted lettuce, spinach, and radishes in May and June, August is your second succession window. These crops bolt in summer heat — but August temperatures are cooling, making them productive again.

Plant short rows every 10–14 days through August for continuous fall harvest. Use the succession planting calculator to time intervals against your first frost date.

Crops to Skip in August

Regardless of zone, avoid starting these in August:

• Tomatoes and peppers: not enough time to mature from transplant
• Winter squash in zones 2–6: frost will arrive before harvest
• Long-season onions from seed: days to maturity too long
• Sweet corn: needs consistently warm soil temperatures

Extending the Season

August plantings benefit enormously from low-cost season extension:

• Floating row cover: adds 2–4°C of frost protection
• Cold frames: add 4–8°C and extend your season by 4–6 weeks in zones 4–5
• Low tunnels with poly film: lets zone 4 gardeners grow zone 5 crops through October

These tools effectively shift you one zone warmer and make late August planting worthwhile even in colder regions.

Your August Planting Checklist

1. Find your first frost date at mygardenplanner.ca/frost-dates-canada
2. Count backwards from that date to identify which crops still have time to mature
3. Prioritize frost-hardy brassicas, greens, and root vegetables
4. Plan succession rows of quick crops (radishes, arugula, lettuce) every 10–14 days
5. Order or source row cover before nights start dipping toward freezing

Canadian gardeners who plan their August succession planting wisely often harvest fresh vegetables well into November — and into December in coastal zones.

Plan your fall garden at mygardenplanner.ca — the free calculator shows exactly what still has time to grow before your first frost.