What to plant in August in USDA zone 9

Sow outdoors in August — zone 9

Direct-sow these seeds into prepared garden beds or large containers. Soil temperature matters more than the calendar date — wait for a sustained warm-up before sowing tender crops.

• Beans, cucumbers, summer squash (fall crop)

Transplant in August — zone 9

Move hardened-off seedlings into the garden. Tender crops want soil above 16 °C and night temperatures consistently above 10 °C; cool-season transplants tolerate light frost.

• Fall tomato, pepper, and eggplant transplants

Harvest in August — zone 9

These crops should be ready or in active harvest in August for zone 9 gardens. Pick fruiting crops every 2-3 days to keep production going.

• Okra, southern peas, sweet potatoes, hot peppers

Prep and planning — zone 9

• Order garlic and shallots for October-November planting

Universal August tasks

These apply across most US and UK gardens in August, regardless of zone.

• Sow autumn salad, spinach, kale, and oriental greens.
• Transplant fall brassicas (broccoli, cabbage, cauliflower) in zones 4-7.
• Preserve the summer harvest — can, freeze, dehydrate, or ferment.
• Order garlic and shallots for fall planting.
• Water consistently — uneven moisture splits tomatoes and bolts greens.
• Cut and dry herbs at peak flavor (just before flowering).

Why this works for zone 9

Zone 9 has average annual minimum temperatures of 20 to 30°F (-7 to -1°C) and a frost-free window from mid-February to early March to late November / early December — about 280 growing days. Heat-tolerant tomato varieties (Solar Fire, Heatwave II) needed for midsummer. Cool-season crops grow Oct-Apr while northern zones are dormant.

Dates are zone-wide averages. Local microclimates (south-facing slopes, urban heat, lakeside warmth, elevation) can shift the window by 1-2 weeks within the same zone.

UK gardeners — August

August is harvest peak and the gateway to autumn. Sow spring cabbage, winter lettuce, spinach, salad onions, and overwintering varieties of broad beans and peas. Harvest sweetcorn, tomatoes, beans, courgettes, soft fruit, and main-crop potatoes.

Source and methodology

Frost-date averages from NOAA Climate Data Online within USDA zone 9. Hardiness boundaries from the USDA Plant Hardiness Zone Map (2023). Crop timing curated against US Cooperative Extension Service publications (UNL, UMN, NC State, Texas A&M, UF/IFAS, Oregon State) and cross-referenced against the RHS sowing calendar. Curated by the Growli editorial team.

Keep going

• ← July in zone 9
• September in zone 9 →
• All zones — what to plant in August
• USDA Zone 9 — frost dates and crop list
• Full 12-month planting calendar

Other zones — August

• What to plant in August in zone 3
• What to plant in August in zone 4
• What to plant in August in zone 5
• What to plant in August in zone 6
• What to plant in August in zone 7
• What to plant in August in zone 8
• What to plant in August in zone 10