Now
21°C · Partly cloudy
Today
21° / 11°
Soil 6 cm
15°C
First frost
~25 days (Oct 3)
Gardening in Edmonton
AI field guide · refreshed weeklyEdmonton Gardening: September 8–14 — Race Against Frost
You're in zone 3b with 25 days until the average first frost (Oct 3). Soil at 15°C is still workable but cooling fast. Spring frost averaged May 11, giving you 120 frost-free days this year—typical for Edmonton. Anything you plant now must mature before early October or be protected. Focus on harvest and cleanup rather than new sowings.
Sow outdoors now
Spinach (Spinacia oleracea 'Space' or 'Bloomsdale')
Direct seed this week in loose soil; germinates at 15°C and matures in 40–50 days, just making it before frost if you sow by Sept 10.
Arugula (Eruca sativa)
Fast crop (30 days to baby leaves). Sow in a sheltered bed; tolerates light frost and tastes better after a chill.
Mâche (Valerianella locusta)
Sow now for fall and overwintering; extremely cold-hardy and germinates reliably at cool soil temps.
Radish (Raphanus sativus 'Cherry Belle')
Matures in 25 days; sow by Sept 12 to harvest before hard frost.
Turnip (Brassica rapa 'Purple Top')
Sow by Sept 10; roots sweeten after frost and store well. Needs 70–80 days but can handle light frosts.
Start indoors now
Microgreens (any brassica or radish seed)
Start in trays indoors for harvest in 10–14 days; extends your growing season past outdoor frost.
Garlic (Allium sativum, any hardneck variety)
Cloves planted indoors now in pots can be hardened off and transplanted outdoors by late September for overwintering and June harvest.
Harvest now
Tomatoes (all varieties)
Pick all fruit—ripe, mature green, or hard green—before frost hits. Ripen indoors at room temp or use in green tomato recipes.
Peppers (Capsicum annuum)
Harvest all peppers, even immature ones; they'll ripen indoors. Plants won't survive frost.
Beans, Peas & Squash (summer crops)
Collect final pods and fruit this week; frost will kill plants within 25 days.
Root crops (beets, carrots, parsnips)
Dig now or mulch heavily in place; light frosts improve flavor but hard freeze will damage exposed shoulders.
Tasks this week
- Cut back perennials (coneflowers, rudbeckia, sedums) to 10 cm (4 in.) or leave standing for winter interest and wildlife.
- Divide spring bulbs (tulips, daffodils) if overcrowded; replant immediately or store in cool, dry place until October.
- Mulch beds with 5–7 cm (2–3 in.) of compost or aged manure before soil freezes; protects roots and enriches soil.
- Clean up fallen leaves and debris to reduce overwintering pests; compost disease-free material or leave in borders for insects.
- Drain and store hoses, irrigation lines, and outdoor taps to prevent freeze damage.
Watch out for
- Frost can arrive any night after Sept 20; cover tender plants with row cloth or cloches if a cold snap is forecast.
- Powdery mildew thrives in cool, damp fall weather—thin crowded plants and water at soil level only.
- Slugs and snails peak in September rain; hand-pick in early morning or use beer traps in wet beds.
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