August is the month of two gardens at once: the summer garden is at peak harvest, and the fall garden must be sown now. In Zone 9, August is your last good window for fall peas, radishes, turnips, carrots and leafy greens: sow them now and they will be ready before the average first frost, Dec 1–15. Wait until September and many of them run out of time.
What August means in Zone 9
USDA Zone 9 covers the warmest parts of the southern United States, including much of Florida, southern Texas, southern Louisiana, southern Arizona and coastal California. Winters are mild, with average winter lows of 20 to 30°F, frost is brief and light, and the growing season runs nearly all year.
The dates that matter most are the frost averages. The average last spring frost in Zone 9 is Jan 30–Feb 15, and the average first autumn frost is Dec 1–15. These are USDA zone averages drawn from NOAA frost records, not exact dates for any one garden. Always check your local extension service and the forecast before planting tender crops outside. Use our frost date calculator for your zone’s averages.
August in Zone 9 is the second spring: fall tomatoes and brassicas go out, peas and beans can be sown again, and the summer harvest is still coming in. The average first frost is not until December, so fall crops have a long, warm runway, but they still need daily watering to get going.
August task list
- Harvest tomatoes, peppers, eggplant, okra, beans and squash: pick often to keep plants producing.
- Sow fall crops: peas, radishes, turnips, carrots, beets, lettuce, spinach and arugula.
- Transplant fall brassicas: broccoli, cabbage, kale and cauliflower.
- Start lettuce, spinach and kale indoors for succession planting.
- Preserve the glut: freeze beans, dry herbs, and make sauce from surplus tomatoes.
- Water deeply, mulch, and feed fall transplants.
- Remove spent summer plants and compost healthy material.
What to start indoors in August
Start these under cover now, with strong light and steady moisture.
- Lettuce — matures in 45–60 days; hardy; soil pH 6.0–7.0.
- Kale — matures in 50–65 days; hardy; soil pH 6.0–7.5.
- Broccoli — matures in 60–85 days; frost-tolerant; soil pH 6.0–7.0.
- Cauliflower — matures in 55–80 days; frost-tolerant; soil pH 6.0–7.0.
What to direct-sow in August
Sow these straight into prepared beds and water the seed row well.
- Peas — matures in 60–70 days; hardy; soil pH 6.0–7.5.
- Green beans — matures in 50–65 days; tender; soil pH 6.0–7.0.
- Carrots — matures in 60–80 days; hardy; soil pH 6.0–6.8.
- Beets — matures in 50–70 days; hardy; soil pH 6.0–7.0.
- Radishes — matures in 25–40 days; hardy; soil pH 6.0–7.0.
What to transplant in August
Harden seedlings off for a week before planting out, and water them in well.
- Tomatoes — matures in 60–85 days; tender; soil pH 6.0–6.8.
- Broccoli — matures in 60–85 days; frost-tolerant; soil pH 6.0–7.0.
- Cabbage — matures in 60–90 days; frost-tolerant; soil pH 6.0–7.0.
- Kale — matures in 50–65 days; hardy; soil pH 6.0–7.5.
What to harvest in August
Pick little and often: regular picking keeps beans, squash and cucumbers producing.
- Tomatoes — tender, matures in 60–85 days.
- Bell peppers — tender, matures in 60–90 days.
- Okra — tender, matures in 50–65 days.
- Eggplant — tender, matures in 70–85 days.
- Sweet potatoes — tender, matures in 90–120 days.
- Green beans — tender, matures in 50–65 days.
- Zucchini — tender, matures in 45–55 days.
August planting at a glance
| Crop | What to do | Days to maturity | Cold tolerance | Spacing |
|---|---|---|---|---|
| Lettuce | Start indoors | 45–60 | hardy | 8–12 in |
| Kale | Start indoors | 50–65 | hardy | 12–18 in |
| Broccoli | Start indoors | 60–85 | frost-tolerant | 18–24 in |
| Cauliflower | Start indoors | 55–80 | frost-tolerant | 18–24 in |
| Peas | Direct sow | 60–70 | hardy | 2–3 in |
All figures are broad published ranges from standard horticultural references, and they vary by variety, soil and weather. Check your local extension service for advice on your own garden.
Soil, water and feeding in August
August soil is warm, which helps fall seeds germinate fast, but it also dries fast, so water new sowings daily until they are up. Fork compost into beds where summer crops have finished, and mulch fall transplants to hold moisture. Feed brassicas once they are growing strongly.
Frost and weather protection
Frost is still weeks away in Zone 9: the average first autumn frost is Dec 1–15, but August is when you start counting backwards from it. Every fall sowing should be timed so the crop matures before that date: radishes need only 25 to 40 days, while carrots need 60 to 80. Keep fleece and row cover ready for the first cold nights, and check your local extension service for your county's frost averages.
Pests and problems to watch
August pests shift to fall crops: cabbage white butterflies lay eggs on young brassicas, so net them from day one. Slugs love damp August nights and young lettuce, so protect seedlings. Keep picking hornworms off tomatoes and remove any blighted leaves to slow disease.
Frequently asked questions
What can I plant in August in Zone 9?
Fall crops: peas, radishes, turnips, carrots, beets, lettuce, spinach, arugula and cilantro. Transplant fall brassicas started indoors in July.
Is August too late to plant tomatoes in Zone 9?
Yes, for fruiting outdoors: tomatoes need 60 to 85 days to mature and will be cut down by your average first frost, Dec 1–15. August is for fall crops, not new tomatoes.
How do I keep fall seeds germinating in August heat?
Water the seed row daily, shade it with boards or shade cloth until seedlings appear, and sow a little deeper than in spring. Warm soil actually speeds germination if it stays moist.
When should I harvest sweet potatoes in Zone 9?
Sweet potatoes need 90 to 120 days and are usually dug in late August or September, before the first frost, Dec 1–15, which damages the roots. Cure them in a warm place for a week or two after digging.
For the full year, browse the planting calendar hub. Nearby months: July in Zone 9, August in Zone 7, August in Zone 8. Use the harvest date calculator to work out exact dates for your own garden.