August in Zone 9
August is the pivot month in Zone 9 — the first half is still brutally hot, but by late August temperatures begin to moderate and the fall planting season kicks off in earnest. Transplant fall brassicas, direct sow fall crops, and begin the transition from summer to cool-season gardening.
Jump to another month
- Min Winter Temp
- 20 to 30 °F / -7 to -1 °C
- Last Spring Frost
- Late January – late February
- First Fall Frost
- Early December – early January
- Growing Season
- 270–310 days
- Annual Rainfall
- 10–55 in
August overview
August transitions from peak summer to late summer. Heat continues but days are shortening noticeably. Fall crop planting is urgent in cold zones, and warm-zone gardeners begin planning for fall gardens. Preserving harvests becomes a priority.
Peak tomato and pepper harvest; urgent fall planting in cold zones; canning and preserving; transplanting fall brassicas; planting spring bulbs ordered early.
- Season
- summer
- Temperature trend
- Still hot but temperatures begin easing late in the month in northern zones.
- Daylight
- Noticeably shortening days; losing 2+ minutes of daylight daily.
- Zone 9 last frost
- Late January – late February
- Zone 9 first frost
- Early December – early January
3
Sow indoors
8
Sow outdoors
7
Transplant
0
Harvest
3
Maintenance
🌱 Sow indoors
Start slow-maturing fall crops indoors
Some fall crops benefit from starting indoors in August to get a head start before outdoor temperatures are fully moderate. This includes lettuce varieties prone to heat dormancy and slow-growing brassicas.
Lettuce Transplants
Start cell trays indoors in air-conditioned space where temperatures stay below 75°F. Lettuce seed germinates poorly above 80°F. Grow for 3–4 weeks before transplanting outdoors in September. Use heat-tolerant varieties like 'Nevada' or 'Jericho'.
Celery
Celery is slow-growing (120 days) and can be started indoors in August for a December–January harvest in Zone 9. Sow seeds on the surface (they need light) at 65–70°F. Pot up once and transplant outdoors in October.
Leeks
Sow seeds ¼ inch deep in cell trays indoors. Leeks transplanted in September–October will be ready for harvest in January–March of next year. 'King Richard' and 'Giant Musselburgh' are reliable Zone 9 performers.
🌿 Sow outdoors
Direct sow fall greens and root vegetables
Late August direct sowing is timed so that seedlings emerge as September temperatures moderate. Crops sown now will be in full production during Zone 9's ideal October–November growing season.
Lettuce
Sow in the evening, ⅛ inch deep, in beds shaded from afternoon sun. Lettuce seed goes dormant (thermodormancy) above 85°F soil temperature — sow in a shaded spot or wait until the soil cools. Germination improves dramatically in September.
Arugula
Broadcast sow and rake lightly into ¼ inch of soil. Arugula germinates reliably in late August's warm soil and is ready for first harvest in 3–4 weeks. More heat-tolerant at germination than lettuce.
Asian Greens (Mizuna, Tatsoi)
Broadcast or row-sow ¼ inch deep; thin to 6 inches. These cool-season greens germinate and grow quickly — mizuna is ready to harvest in 40 days. Extremely productive in Zone 9's fall and winter.
Beets
Sow 1 inch deep, 3 inches apart, in rows 12 inches apart. Late-August beets are ready to harvest in October–November. 'Red Ace' and 'Chioggia' are reliable performers for Zone 9 fall plantings.
Radishes
Sow ½ inch deep, 1 inch apart. August-sown radishes mature in 25–30 days — a great way to test bed conditions while waiting for slower crops to establish. Succession sow every 2 weeks through October.
Direct sow fall beans and cucumbers
Zone 9's fall warm season extends through October–November, giving beans and cucumbers planted in August a full 60–75 days of productive weather before cool nights slow growth in December.
Bush Beans
Sow 1 inch deep, 3–4 inches apart, in rows 18 inches apart. Fall beans planted in late August produce in October–November when pest pressure (spider mites, bean beetles) is lower than in summer, often resulting in better yields.
Cucumbers
Sow 1 inch deep in hills 3–4 feet apart, 3 seeds per hill thinned to 2. August-planted cucumbers produce prolifically in October before the first cool snap. Train on a trellis for cleaner fruit and better air circulation.
Summer Squash
Sow 1 inch deep in hills 3–4 feet apart, thinning to 2 plants. Fall squash planted in August often out-produces spring squash in Zone 9 because it grows without the extreme summer heat that stresses plants and causes blossom drop.
🪴 Transplant
Transplant fall brassica starts outdoors
Brassica transplants started indoors in July are ready to move outside by mid-to-late August when temperatures begin to drop below 100°F. Getting plants in the ground now allows them to establish before the ideal October–November growing conditions arrive.
Broccoli
Transplant in the evening or on a cloudy day to reduce transplant stress. Space 18–24 inches apart. Water in with dilute liquid seaweed fertilizer. Provide temporary shade cloth (50%) for the first week if transplanting in early August heat.
Cabbage
Set out 18–24 inches apart. Cabbage transplants started in late July will be 3–4 weeks old — the ideal size for transplanting. Firm soil well around roots and water immediately. Mulch to conserve soil moisture.
Cauliflower
Transplant 18–24 inches apart in beds amended with balanced fertilizer. Cauliflower is the most cold-sensitive brassica — it will head up nicely in Zone 9's October–November cool season if transplanted now.
Kale
Set out 18–24 inches apart. Kale is the most heat-tolerant brassica — it can be transplanted in August with minimal stress compared to cauliflower. 'Lacinato' (Dinosaur kale) and 'Red Russian' both perform well in Zone 9 fall gardens.
Set out fall tomato and pepper transplants
Fall tomatoes and peppers transplanted in late August have 10–14 weeks before Zone 9's first frost in December — enough time for a full productive harvest from plants that establish in warm, favorable conditions.
Fall Tomatoes
Transplant in late August or early September when daytime highs drop below 100°F. Bury stem deeply as with spring plantings. Stake immediately. These plants will fruit heavily in October–November as Zone 9 temperatures drop into the ideal 70–85°F range for fruit set.
Fall Peppers
Set out 18–24 inches apart. Fall pepper plants establish quickly in late August's warm soil and begin producing prolifically by October. Often out-produce spring plantings in Zone 9 because fruit sets in ideal fall temperatures.
Fall Eggplant
Transplant in late August if starting fresh, or allow spring plants to continue — eggplant often rebounds strongly when August heat moderates slightly. Cut back spring plants by one-third in early August to stimulate new growth for fall production.
🛠️ Maintenance
Renovate and amend beds vacated by summer crops
As summer crops are pulled out, this is the prime opportunity to improve soil before the intensive fall planting season. Well-amended soil in August sets up exceptional fall and winter productivity.
Compost Incorporation
Add 3–4 inches of mature compost to cleared beds and work into the top 8–10 inches. If summer cover crops were sown, terminate and incorporate them now. Water the amended bed and allow to settle for 1–2 weeks before fall planting.
Fertilizer Application
Broadcast a balanced granular fertilizer (6-4-4 or similar) at the recommended rate and incorporate. Alternatively, use cottonseed meal (6-2-1) as a slow-release organic nitrogen source that feeds through the entire fall season.
Irrigation System Check
Flush drip lines and check all emitters before the fall planting season begins. Replace clogged emitters, repair cracked tubing, and reprogram timers for fall watering schedules (less frequent than summer, but still needed through October).
General August tasks
These apply broadly regardless of zone — a useful checklist alongside the zone-specific tasks above.
- ✓Direct sow fall spinach, arugula, and lettuce in cold and temperate zones
- ✓Transplant fall broccoli, kale, and chard starts
- ✓Plant fall-bearing strawberries
- ✓Order spring bulbs for fall planting
- ✓Harvest and preserve: tomatoes, peppers, cucumbers, beans
- ✓Sow cover crops in empty beds to suppress weeds and build soil
- ✓Reduce fertilizing on perennials to encourage hardening-off before winter
- ✓Deadhead spent flowers to extend bloom or let seed heads form for birds
⚠ Watch-outs for August
- ⚠Late August is the last chance to plant fall crops in cold zones (Zones 3–5) — time is short
- ⚠Tomato late blight can spread rapidly in cool, wet August conditions — inspect daily
- ⚠End-of-season exhaustion in squash and cucumber plants — pull when productivity drops
- ⚠Fall armyworms arrive in the South in August — inspect grass and leafy crops
August in Zone 9: common questions
What can I plant in August in Zone 9?＋
In August, Zone 9 gardeners can sow or transplant Lettuce Transplants, Celery, Leeks, Lettuce, Arugula, Asian Greens (Mizuna, Tatsoi), Beets, and Radishes. August is the pivot month in Zone 9 — the first half is still brutally hot, but by late August temperatures begin to moderate and the fall planting season kicks off in earnest. Transplant fall brassicas, direct sow fall crops, and begin the transition from summer to cool-season gardening.
When is the last and first frost in Zone 9?＋
Zone 9 typically has its last spring frost around Late January – late February and its first fall frost around Early December – early January, giving a growing season of roughly 270–310 days. Always check a local frost-date source, since microclimates vary.
What garden jobs matter most in August in Zone 9?＋
Focus on direct sow fall spinach, arugula, and lettuce in cold and temperate zones, transplant fall broccoli, kale, and chard starts, plant fall-bearing strawberries. Watch out for late august is the last chance to plant fall crops in cold zones (zones 3–5) — time is short.