Now
26°C · Partly cloudy
Today
25° / 17°
Soil 6 cm
20°C
First frost
~48 days (Oct 26)
Gardening in Madison
AI field guide · refreshed weeklyMadison Gardening: Early September — Sow Fall Crops, Harvest Summer Bounty
Zone 5a, first fall frost Oct 26 (48 days away). Soil at 20°C is ideal for direct seeding cool-season crops; they'll establish before soil temps drop below 15°C in late September. You have roughly 7 weeks of reliable growing before hard frost. Spring frost was Apr 29, so you're 132 days into the season — peak harvest time for summer crops.
Sow outdoors now
Spinach (Bloomsdale, Space or Tyee)
Direct seed now; germinates quickly at 20°C soil. Matures in 40–50 days, well before frost. Thin to 10 cm (4 in) apart.
Arugula (Roquette)
Fast crop (30 days to harvest). Sow every 2 weeks through mid-September for continuous fall harvest. Prefers cool weather.
Radish (Cherry Belle, Icicle)
Matures in 25–30 days at this soil temp. Plant in succession every 10 days for staggered harvest into October.
Kale (Lacinato, Winterbor)
Sow now for mature plants by frost; flavor improves after light frost. Thin to 30 cm (12 in) spacing.
Mâche (Corn Salad)
Extremely cold-hardy; sow now for fall and overwinter harvest. Germinates at cool temps; thin to 15 cm (6 in).
Start indoors now
Broccoli & Cabbage transplants (if not already started)
Start indoors now for transplant in 3–4 weeks; needs 6–8 weeks to mature before frost. Use varieties like 'Packman' broccoli or 'Red Acre' cabbage.
Leeks (Titan, King Richard)
Start indoors; transplant out in 2 weeks for 12–14 weeks growth before frost. Harvest from late October onward.
Harvest now
Tomatoes (all types)
Pick ripe fruit now; nights cooling toward 15°C slow ripening. Harvest green tomatoes before first frost (Oct 26) and ripen indoors.
Peppers (sweet & hot)
Pick mature peppers now; plants slow production as temps drop. Leave some on plant to ripen fully if frost holds off.
Beans (snap, pole, dry)
Harvest snap beans at peak tenderness; let dry beans mature on plant. Pull plants before first frost to finish drying indoors.
Summer squash & Zucchini
Pick regularly to encourage production. Plants will decline after first light frost; plan to remove by late October.
Tasks this week
- Deadhead spent flowers on perennials and annuals to extend bloom and redirect energy.
- Water deeply 2–3 times this week if rain doesn't arrive; soil at 20°C still supports active growth.
- Scout for Japanese beetles, aphids, and spider mites on fall crops — treat early with neem or insecticidal soap.
- Cut back spent perennials (coneflowers, black-eyed Susans) to tidy beds and reduce disease overwintering.
- Divide spring-blooming perennials (hostas, daylilies) now for transplant; they'll establish before dormancy.
Watch out for
- Powdery mildew thrives in cool, humid nights (75% humidity forecast) — ensure good air flow and avoid overhead watering.
- Early blight on tomatoes accelerates as nights cool; remove lower leaves and harvest green fruit before frost.
- Slugs and snails peak in fall dampness — handpick at dusk or use beer traps in garden beds.
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