Now
20°C · Overcast
Today
20° / 17°
Soil 6 cm
19°C
First frost
~40 days (Oct 18)
Gardening in Thunder Bay
AI field guide · refreshed weeklyThunder Bay Gardening: Early Fall Harvest & Winter Prep
You're in zone 5a with 40 days until the average first frost (Oct 18). Soil at 19°C is still warm enough for quick-maturing crops, but nights are cooling fast—frost can arrive any night after mid-October. This is your critical window for fall harvest and planting cold-hardy overwintering crops.
Sow outdoors now
Spinach (Bloomsdale, Space)
Sow directly now for October harvest; germinates well in 15–19°C soil and tolerates light frosts.
Mâche (corn salad)
Cold-hardy salad green that thrives in Thunder Bay's cool fall; direct sow and thin to 10 cm spacing.
Radish (Cherry Belle, Icicle)
Matures in 25–30 days; plant now for late-September to early-October harvest before hard frost.
Arugula
Fast-growing peppery green; sow every 2 weeks through mid-September for continuous fall harvest.
Garlic (German Extra Hardy, Music)
Plant cloves 5 cm deep, 15 cm apart, now through September for spring harvest; mulch heavily after ground freezes.
Start indoors now
Kale (Lacinato, Winterbor)
Start seeds indoors now for transplant in 3–4 weeks; these varieties sweeten after frost and produce through November.
Leeks (Titan, Bulgarian Giant)
Sow indoors now, transplant outdoors in late September; harvest from October onward as needed.
Cabbage (January King, Tundra)
Start indoors this week for transplant in 2–3 weeks; both store well and tolerate hard frosts.
Harvest now
Tomatoes (all varieties)
Pick all remaining fruit, including green ones; ripen indoors at room temperature or use for green tomato chutney.
Beans (bush and pole)
Harvest pods before frost; plants will die at first hard freeze.
Squash & Pumpkins
Cut with 5 cm stem; cure in a warm, dry place for 2 weeks before storage.
Potatoes
Dig now before soil cools further; cure in darkness at 10–15°C for 2 weeks to harden skin.
Tasks this week
- Mulch beds with 5–8 cm of straw or leaves to insulate soil and extend the growing season for cold-hardy crops.
- Cut back dead perennials and ornamental grasses; leave some standing for winter structure and wildlife shelter.
- Plant spring bulbs (tulips, daffodils, crocus) now through October; soil is still warm enough for good root establishment.
- Drain and store garden hoses; shut off outdoor water before the first hard freeze.
- Scout for aphids and mites on remaining plants; a strong spray of water or insecticidal soap works in cool weather.
Watch out for
- Frost can arrive any night now—cover tender plants or harvest before the forecast dips below 0°C.
- Wind gusts to 31 km/h (Sept 9) may topple tall plants or break branches; stake or tie down as needed.
- Wet soil (13.6–15.6 mm rain forecast Sept 11–12) can cause root rot in poorly drained beds; ensure good drainage before heavy rain.
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