Now
28°C · Clear
Today
31° / 20°
Soil 6 cm
23°C
First frost
~33 days (Oct 11)
Gardening in Fargo
AI field guide · refreshed weeklyFargo Gardening: September 8–14 — Harvest, Sow Cool Crops, Prepare for Frost
You're in zone 4a with 33 days until the average first frost (October 11). Soil at 23°C (73°F) is still warm enough for cool-season crops to germinate and establish before hard freeze. Frost-free days are nearly exhausted; prioritize quick-maturing varieties. Spring frost risk is gone; fall frost risk is rising fast.
Sow outdoors now
Spinach (e.g., 'Space' or 'Bloomsdale Long Standing')
Sow directly into soil this week; germinates in 7–10 days at 23°C and matures in 40–50 days before hard frost. Tolerates light frosts once established.
Arugula (e.g., 'Roquette' or 'Astro')
Direct sow now for 30–40 day harvest; thrives in cooling temperatures and survives light frosts. Sow thickly in rows or broadcast.
Radish (e.g., 'Cherry Belle' or 'French Breakfast')
Matures in 25–30 days; sow now for late-September/early-October harvest before soil freezes. Prefers cool weather and won't bolt.
Lettuce (e.g., 'Winter Density' or 'Buttercrunch')
Sow leaf or head lettuce; 45–60 day varieties will mature by early November if protected. Cold-hardy types survive light frosts.
Mâche (Corn Salad)
Extremely cold-hardy; sow now for fall and overwintering harvest. Germinates slowly (14–21 days) but thrives as temperatures drop.
Start indoors now
Kale (e.g., 'Lacinato' or 'Winterbor')
Start seeds indoors now for transplant in 3–4 weeks; kale matures in 55–75 days and improves in flavor after frost. Hardiness zone 4 standard.
Cabbage (e.g., 'Red Acre' or 'Savoy')
Start now for 6–8 week transplant window; late-season cabbage stores well and tolerates frost. Avoid long-season varieties (>90 days).
Broccoli (e.g., 'Packman' or 'Green Goliath')
Start indoors for transplant by late September; 50–70 day varieties will head before hard frost if planted by September 20.
Harvest now
Tomatoes (all remaining fruit)
Harvest all fruit—ripe, breaker stage, or green—before frost arrives in 33 days. Green tomatoes ripen indoors in 2–3 weeks at room temperature.
Peppers (all stages)
Pick all peppers, green or colored, before first frost. They'll continue ripening indoors but won't mature further on the plant.
Beans (dry or snap)
Harvest snap beans while tender; leave dry beans on vine until pods brown and rattle, then shell and dry indoors.
Squash and Pumpkins
Harvest when skin hardens and resists thumbnail; cure in a warm, dry spot for 7–10 days before storage to harden skin.
Tasks this week
- Plant garlic cloves 5 cm (2 in) deep in well-draining soil; they'll root before winter and sprout in spring. Use local varieties or 'German Extra Hardy.'
- Remove spent tomato, pepper, and bean plants; compost disease-free material, discard any with blight or fungal issues.
- Mulch beds with 5–8 cm (2–3 in) of straw or shredded leaves to insulate soil and suppress weeds through fall.
- Water newly sown cool-season crops deeply if no rain falls; soil at 23°C dries quickly despite cooler air.
- Scout for aphids, spider mites, and cabbage moths on fall brassicas and leafy greens; hand-pick or use neem oil if needed.
Watch out for
- First frost arrives in ~33 days (October 11 average); tender annuals will die. Protect brassicas and greens with row cover if frost threatens earlier than forecast.
- Dry conditions this week (0 mm rain forecast through September 13) mean newly sown seeds need consistent moisture; water gently after sowing.
- Powdery mildew thrives in cool, dry fall weather; thin dense plantings and avoid overhead watering to reduce humidity on foliage.
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