Now
32°C · Overcast
Today
35° / 24°
Soil 6 cm
28°C
First frost
~43 days (Oct 21)
Gardening in Omaha
AI field guide · refreshed weeklyOmaha Gardening: Early September – Sow Cool-Season Crops, Harvest Summer Bounty
Zone 5a means your first fall frost arrives around October 21—43 days away. Soil at 28°C (82°F) is still warm enough for quick germination of cool-season crops; nighttime temps are dropping fast, which these crops prefer. You have roughly 6–7 weeks of reliable growing weather before frost, perfect for leafy greens, root crops, and brassicas that thrive in cooling soil.
Sow outdoors now
Spinach (Bloomsdale, Space or Tyee)
Direct seed now; germinates in 7–10 days at 28°C soil temp and grows fast in cooling weather. Harvest in 40–50 days before frost.
Lettuce (Buttercrunch, Oakleaf, Winter Density)
Sow every 10 days through mid-September for continuous harvest. Prefers temps below 24°C; thrives as nights cool.
Radish (Cherry Belle, Watermelon)
Ready in 25–30 days; sow now and again in 2 weeks for fall harvest. Tolerates light frost.
Kale (Winterbor, Lacinato)
Sow now for October–November harvest; flavor improves after light frost. Germinates reliably at current soil temps.
Arugula (Roquette)
Sow thickly; ready in 30–40 days. Peppery flavor peaks in cool fall weather; succession-sow every 2 weeks.
Start indoors now
Cabbage transplants (Golden Acre, Savoy)
Start seeds indoors now for transplant in 4–5 weeks; gives them time to head up before hard frost.
Broccoli (Arcadia, Belstar)
Sow indoors; transplant in 4 weeks for October harvest. Needs cool nights to form tight heads.
Cauliflower (Snowball Y, Cheddar)
Start indoors now; transplant by late September for November harvest before zone 5a frost.
Harvest now
Tomatoes (all types)
Pick ripe fruit now; nights are cooling and frost risk rises. Green tomatoes ripen indoors in 2–3 weeks on a sunny windowsill.
Peppers (bell, hot)
Harvest mature peppers; immature fruit won't ripen before frost. Pull entire plants if frost is forecast and hang to finish.
Beans (bush and pole)
Pick regularly to encourage final flush; frost will end production by late October.
Summer squash and zucchini
Harvest at peak tenderness; plants slow as nights cool. Remove any diseased leaves to extend season.
Tasks this week
- Water deeply after rain (13.5 mm forecast Sept 9); cool-season crops need consistent moisture as soil cools.
- Deadhead spent flowers on perennials to redirect energy before dormancy; cut back ornamental grasses if desired.
- Scout for spider mites and aphids on remaining warm-season crops; spray neem oil early morning if needed.
- Mulch newly planted cool-season crops lightly to retain moisture and moderate soil temp swings.
- Stake or support fall brassicas if wind gusts reach 30+ km/h (forecast Sept 11, 14) to prevent root damage.
Watch out for
- Frost risk is still 43 days away, but a surprise early cold snap is possible in zone 5a—keep frost cloth and row covers handy.
- Powdery mildew thrives in cool, humid fall nights; thin crowded plantings and avoid overhead watering after 3 p.m.
- Slugs and snails accelerate in fall moisture; hand-pick at dusk or use beer traps around tender seedlings.
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