Now
21°C · Overcast
Today
23° / 14°
Soil 6 cm
20°C
First frost
~28 days (Oct 6)
Gardening in Winnipeg
AI field guide · refreshed weeklyWinnipeg Gardening: Early September – Harvest, Sow Cool Crops, Prepare for Frost
You're in zone 4a with 28 days until the average first frost (October 6). Soil at 20°C is still warm enough for cool-season crops but cooling fast. Spring frost arrived May 14, giving you 117 frost-free days so far. Plan all sowings and plantings with frost date in mind—anything needing more than 4 weeks to maturity should go in this week or be started indoors now.
Sow outdoors now
Spinach (Spinacia oleracea)
Direct sow 'Space' or 'Bloomsdale Long Standing' now; germinates well at 20°C soil and matures in 40–50 days before frost. Sow thickly in rows 15 cm (6 in) apart.
Arugula (Eruca vesicana)
Sow 'Roquette' or 'Wild Rocket' directly; ready in 30–40 days. Tolerates light frost and tastes better after a chill. Space 10 cm (4 in) apart.
Radish (Raphanus sativus)
Plant 'Cherry Belle' or 'French Breakfast' for a quick 25–30 day harvest before frost. Sow every 2 cm (0.75 in) in rows 15 cm apart.
Mâche (Valerianella locusta)
Sow 'Verte de Cambrai' now for a cold-hardy salad green; germinates at cool temps and overwinters under mulch or snow. Space 15 cm apart.
Turnip (Brassica rapa)
Direct sow 'Purple Top' or 'Hakurei' for roots and greens; matures in 50–60 days. Thin to 10 cm (4 in) spacing; frost improves flavor.
Start indoors now
Kale (Brassica oleracea)
'Winterbor' and 'Lacinato' germinate in 7–10 days indoors at room temp; transplant in 3–4 weeks for a late-season harvest and cold hardiness. Sow in seed trays.
Chard (Beta vulgaris subsp. cicla)
Start 'Bright Lights' or 'Fordhook Giant' indoors now; transplant in 4 weeks for harvest before hard frost. Tolerates light frost once established.
Cabbage (Brassica oleracea var. capitata)
Sow 'Gonzales' (mini) or 'Savoy Perfection' indoors for transplant in 3–4 weeks; heads form before frost. Sow 2–3 seeds per cell.
Harvest now
Tomato (Solanum lycopersicum)
Pick all fruit now—green, turning, or ripe—before frost arrives in 28 days. Ripen indoors on a sunny windowsill or in a paper bag with an apple.
Pepper (Capsicum annuum)
Harvest all peppers, green or colored; frost will kill plants within weeks. Store in a cool room to continue ripening slowly.
Beans (Phaseolus vulgaris)
Pick all pods now; frost will blacken plants. Dry mature pods for seed or shell for fresh beans.
Squash & Zucchini (Cucurbita pepo)
Harvest all fruit before frost; cut with 5 cm (2 in) stem attached. Store winter squash in a cool, dry place; use summer squash fresh.
Tasks this week
- Mulch root crops (carrots, beets, turnips) with 10 cm (4 in) of straw to extend harvest into October and protect from early frost.
- Deadhead spent flowers on perennials to redirect energy to roots before dormancy; cut back ornamental grasses by half.
- Water newly transplanted seedlings and fall crops daily if rain is absent; soil at 20°C dries quickly in 29 km/h wind.
- Scout for aphids and spider mites on brassicas and leafy greens; spray with insecticidal soap if populations spike.
- Clean and oil garden tools before storage; drain hoses and shut off outdoor water if frost threatens this week.
Watch out for
- Frost risk: Lows of 9°C (48°F) arrive by September 13; cover tender crops (tomatoes, peppers, basil) with row cover or cloches on clear nights.
- Wind: Gusts to 34 km/h (21 mph) this week can topple tall crops and dry soil fast—stake tomatoes and water deeply after windy days.
- Powdery mildew: Cool nights and high humidity favor fungal spread on squash and beans; improve air flow and avoid wetting foliage.
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