Fall · September 8, 2026
Philadelphia, Pennsylvania
Now
28°C · Partly cloudy
Today
29° / 15°
Soil 6 cm
23°C
First frost
~63 days (Nov 10)
Gardening in Philadelphia
AI field guide · refreshed weeklyPhiladelphia Gardening: Early September — Sow Fall Crops, Divide Perennials, Prepare for Frost
Zone 7b with 63 days until the average first frost (Nov 10). Soil at 23°C (73°F) is ideal for cool-season seed germination. You're in the sweet spot for fall planting: warm enough for seeds to sprout quickly, but cool nights are coming to slow bolting. Spring frost typically arrives mid-April, giving you a long season ahead.
Sow outdoors now
Spinach (Bloomsdale Long Standing, Space)
Direct sow now; germinates in 7–10 days at 23°C soil temp. Succession-sow every 2 weeks through late September for continuous harvest into November.
Arugula (Roquette, Astro)
Fast crop (30–40 days). Sow densely in rows 15 cm (6 in) apart; thin to 10 cm (4 in). Thrives in cool fall weather and won't bolt as it would in summer.
Radish (Cherry Belle, French Breakfast)
Matures in 25–30 days. Sow 1 cm (0.4 in) deep, 5 cm (2 in) apart. Pair with slower crops (like spinach) to mark rows.
Lettuce (Buttercrunch, Jericho, Winter Density)
Sow every 10 days through mid-October for staggered harvests. Prefers 15–18°C (59–64°F) nights; fall conditions are perfect.
Kale (Lacinato, Winterbor, Red Russian)
Sow now for harvest starting in 50–60 days; flavor improves after light frost. Space 30 cm (12 in) apart; tolerates cold and light snow.
Start indoors now
Brassicas for transplant (Broccoli, Cabbage, Cauliflower)
Start seeds indoors now; transplant outdoors in 4–5 weeks (early October) for November–December harvest. Use varieties like Calabrese, Savoy Ace, or Snowball.
Onions (Egyptian Walking Onion sets, or seed for spring)
If starting from seed, sow now for spring transplant. Walking onions can be planted as sets immediately outdoors for perennial production.
Garlic (hardneck or softneck cloves)
Plant individual cloves directly outdoors in late September–early October (4–6 weeks), not indoors. Start now by sourcing certified seed garlic.
Harvest now
Tomatoes (all varieties)
Pick all remaining fruit before first frost (Nov 10). Green tomatoes ripen indoors on a sunny windowsill in 2–3 weeks; store at 20–21°C (68–70°F).
Peppers (sweet and hot)
Harvest mature fruit now. Plants will produce until frost; pick regularly to encourage more blooms.
Summer squash and zucchini
Cut daily to keep plants productive. Frost will kill plants in 8–10 weeks; use or preserve surplus now.
Beans (bush and pole)
Pick pods when tender. Frost will end production by late October; succession plantings from July may still flower.
Tasks this week
- Divide and transplant spring-blooming perennials (daylilies, coneflowers, black-eyed Susans) while soil is still warm; they'll establish roots before winter dormancy.
- Deadhead spent flowers on asters, sedum, and mums to encourage late blooms and redirect energy to roots.
- Scout for Japanese beetles and squash bugs on remaining warm-season crops; hand-pick or use neem oil if populations spike.
- Mulch newly planted fall crops with 2.5 cm (1 in) compost to retain moisture and moderate soil temperature swings.
- Cut back ornamental grasses and perennials only after frost blackens foliage; leaving them standing protects crowns and provides winter structure.
Watch out for
- Powdery mildew on squash, beans, and peas thrives in cool, humid mornings; improve air flow and water at soil level only.
- Cabbage worms and imported cabbageworms will target all brassicas; use row covers or Bt (Bacillus thuringiensis) spray weekly on transplants.
- Early frost risk: Monitor forecasts closely after Oct 15; have frost cloth or row covers ready for tender crops.
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