Now
37°C · Clear
Today
37° / 25°
Soil 6 cm
34°C
First frost
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Gardening in Tucson
AI field guide · refreshed weeklyTucson Garden Guide: Early Fall Planting Season Begins
You're in zone 9b with 99 days until your first frost (mid-December). Soil is still hot at 34°C (93°F)—wait for it to drop below 27°C (80°F) before sowing most seeds directly, which typically happens in late September. Your 299 frost-free days mean you can grow cool-season crops through winter and into spring. This week's heat and low humidity are typical; the small chance of rain Sept 13–14 won't break the drought pattern.
Sow outdoors now
Peas (snap and snow)
Wait until late September when soil cools; direct-sow now into pots indoors to transplant in 3–4 weeks. Try 'Sugar Snap' or desert-adapted heirloom varieties.
Lettuce and leafy greens
Start seeds indoors now (spinach, arugula, Swiss chard); transplant seedlings outdoors in 2–3 weeks when soil drops below 27°C. Succession-sow every 2 weeks through November.
Root vegetables (carrots, beets, radishes)
Direct-sow into pots indoors now; transplant seedlings to garden beds in late September. 'Nantes' carrots and 'Detroit Dark Red' beets thrive in Tucson winters.
Herbs (cilantro, parsley, dill)
Start seeds indoors now; cilantro especially prefers cool soil and will bolt if sown too early outdoors. Transplant in 3 weeks.
Broccoli and cabbage transplants
Sow seeds indoors now (8–10 weeks before your Dec 16 frost); buy nursery transplants if you want to plant out in late October. 'Packman' broccoli is reliable here.
Start indoors now
Tomatoes (cold-tolerant varieties)
Sow 'Siberia', 'Glacier', or 'Sub-Arctic Plenty' indoors now for transplanting in late October; these will fruit before your spring frost and extend your season.
Peppers (long-season)
Start 'Anaheim' or 'Poblano' indoors now for transplanting in late October; they'll produce through winter and into spring in zone 9b.
Eggplant
Sow indoors now for late-October transplanting; 'Orient Express' and 'Ichiban' are fast-maturing and suited to Tucson's heat recovery in spring.
Harvest now
Summer squash and zucchini
Pick daily if still producing; plants will decline as heat stress peaks this week. Plan to pull them by late September.
Basil
Harvest heavily before first frost in December; pinch flowers to extend leaf production. Freeze or dry excess.
Peppers and eggplant
Continue harvesting mature fruit; plants will slow but may produce through October if watered deeply and mulched.
Tasks this week
- Water deeply and mulch all beds with 5 cm (2 in) of wood chips to moderate soil temperature and retain moisture during the dry spell.
- Scout for spider mites and whiteflies on remaining summer crops; spray with neem oil in early morning if infestations appear.
- Prepare garden beds for fall planting: amend with 2–3 cm (1 in) compost and aged manure; let settle for 1 week before sowing.
- Set up shade cloth (30–50%) over seedling trays indoors to prevent heat stress; keep soil moist but not waterlogged.
- Check irrigation lines and drip emitters; Tucson's low humidity means soil dries fast even in fall.
Watch out for
- Soil still too hot: direct-seeding most crops now will cause germination failure or bolting. Wait until late September.
- Monsoon remnants: the 25 mm (1 in) rain forecast for Sept 14 may bring wind gusts to 18 km/h (11 mph)—stake tall seedlings and secure shade cloth.
- Dust and low humidity: seedlings dry out rapidly; check moisture daily and mist if needed.
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