What to Plant in August in the US: Sowing Guides by USDA Zone

In August, gardening in the United States requires a dual focus on harvesting summer crops and planting for the autumn and winter seasons. While northern gardeners in zones 3 and 4 are racing against early autumn frosts, growers in southern zones 9 and 10 are starting seeds for their primary winter growing season. Successful planting during this transitional month depends entirely on your local USDA hardiness zone and your average first frost date.

Understanding August planting timelines

August planting is a calculation of subtraction. To determine what you can successfully grow, you must look up your average local frost dates and count backward by the number of days the crop needs to reach maturity. To this number, add an extra ten to fourteen days, known as the fall factor, to account for the slower growth rates that occur as day lengths shorten in autumn.

During this month, northern regions experience rapidly cooling nights, while southern regions continue to face intense summer heat. Sowing seeds in August requires careful management of soil moisture and soil temperature, as high heat can inhibit the germination of cool-season crops like lettuce and spinach. Utilizing techniques like midsummer sowing under shade cloth or starting seeds indoors can help overcome these temperature barriers.

USDA Zones 3–4: Northern tier and mountain regions

In USDA zones 3 and 4, the first autumn frost typically arrives between mid-September and early October. This leaves a very short window for August planting. Focus entirely on fast-growing, frost-tolerant crops that can reach harvestable size in thirty to forty-five days.

1. Spinach and winter lettuce

Sow spinach and cold-tolerant lettuce varieties directly into garden beds during the first week of August. These crops germinate quickly in late summer soils but will need protection, such as floating row covers or cold frames, as nights turn chilly in September. Spinach is highly cold-tolerant and will survive light frosts, often sweetening in flavor after exposure to cold.

2. Radishes and arugula

Radishes and arugula are among the fastest-maturing crops available, often ready for harvest in three to four weeks. Sow seeds directly in shallow drills spaced twelve inches apart. Keep the soil consistently moist to prevent the radish roots from becoming woody and to keep the arugula leaves tender and mild.

3. Kale and mustard greens

Sow kale and mustard greens in early August. While these plants will not reach the giant sizes of spring-planted brassicas, they will produce abundant, tender baby leaves for autumn salads. Baby kale is exceptionally hardy and can withstand freezing temperatures, allowing for harvests well into late autumn.

USDA Zones 5–6: Midwest, Northeast, and Mid-Atlantic

For gardeners in zones 5 and 6, the first frost generally occurs in mid-to-late October. This zone band has a wider selection of crops for August planting, including both direct-sown root vegetables and transplanted brassicas.

1. Carrots and beets

Direct-sow carrots and beets during the first two weeks of August. These root crops require sixty to seventy-five days to mature, making early August the final safe window for sowing. To ensure successful germination in hot, dry August soil, sow seeds slightly deeper than in spring, cover them with compost or vermiculite, and keep the seedbeds continuously damp by covering them with boards or burlap until the seeds sprout.

2. Broccoli, cabbage, and kale transplants

Plant out sturdy transplants of broccoli, cabbage, cauliflower, and kale that were started indoors in June or July. August transplanting allows these crops to mature during the cool autumn months, which prevents them from bolting and improves their overall flavor. Ensure they receive consistent irrigation to help their root systems establish in the summer heat. Refer to our list of cold-hardy vegetables to select the most resilient cultivars for your region.

3. Bush beans

Sow a final crop of quick-maturing bush snap beans during the first week of August. Bush beans typically require forty-five to fifty-five days to produce. Sowing them in early August ensures they flower and set pods before the cooler temperatures of October slow their growth.

USDA Zones 7–8: Upper South and Pacific Northwest

In zones 7 and 8, the first frost does not usually arrive until November. This extended growing window makes August one of the busiest months of the year for establishing a productive autumn and winter garden. Calculate your specific fall planting dates to optimize your schedule.

1. Swiss chard and collard greens

Direct-sow or transplant Swiss chard and collard greens throughout August. These leafy greens are highly resilient, tolerating both late-summer heat and moderate winter freezes. August-planted collards will grow steadily through autumn and provide continuous harvests throughout the winter months in these milder zones.

2. Turnips and rutabagas

Sow turnip and rutabaga seeds directly into loose soil during mid-to-late August. Turnips grow rapidly and can be harvested for both their nutritious greens and their roots. Rutabagas take slightly longer to mature but develop an exceptionally sweet flavor after they are exposed to autumn frosts.

3. Cauliflower and Brussels sprouts transplants

Set out transplants of cauliflower, Brussels sprouts, and sprouting broccoli. These long-season brassicas benefit from the warm August soils to establish strong root systems, but they require consistent moisture. Mulch heavily around the base of the plants to conserve soil moisture and lower root temperatures.

USDA Zones 9–10: Gulf Coast, Southwest, Florida, and California

In USDA zones 9 and 10, August is the start of the second major growing season. The intense summer heat begins to subside slightly toward the end of the month, allowing gardeners to plant warm-season crops for a late autumn harvest and start cool-season crops for winter. For detailed advice on southern coastal climates, consult our guide on Deep South fall gardening.

1. Tomatoes and peppers (transplants)

In early August, transplant young tomato and pepper starts into the garden. These plants will grow rapidly in the late summer warmth, flowering and setting fruit during the mild autumn months before winter arrives. Choose quick-maturing, determinate tomato varieties to ensure a heavy harvest before the shorter days of late autumn.

2. Squash and cucumbers

Direct-sow summer squash, zucchini, and slicing cucumbers. These fast-growing warm-season crops will produce heavily in October and November. Monitor young plants closely for pests like squash bugs and cucumber beetles, which are highly active in late summer.

3. Brassicas (indoor seed starting)

Start seeds of broccoli, cabbage, cauliflower, kale, and collards indoors or in a shaded, protected nursery area. The outdoor soil is too hot for reliable germination of these cool-season crops in August. Raising them in a temperature-controlled environment ensures healthy transplants that will be ready to go into the garden beds in late September or October when temperatures cool.

Essential August gardening jobs

To support your newly planted crops and maintain the health of your existing garden, several seasonal tasks must be completed during August:

1. Mulching and moisture management

High evaporation rates in August can rapidly dry out seedbeds and stress young transplants. Apply a two-inch layer of clean straw, shredded leaves, or wood chips around transplants to conserve soil moisture and regulate soil temperatures. For direct-sown beds, use temporary shade cloth or lightweight row covers to reduce moisture loss during the critical germination phase.

2. Shading young transplants

Tender young transplants of brassicas and leafy greens can easily scorch under the intense August sun. Erect temporary shade structures using shade cloth or cheesecloth supported by hoops. Position the shade on the south and west sides of the plants to block the hottest afternoon rays while still allowing morning light to reach the crops.

3. Pest monitoring and crop hygiene

Pest populations peak in late summer. Inspect the undersides of leaves daily for pest eggs, aphids, and caterpillars. Remove any spent or diseased summer crop debris immediately to prevent pests and fungal pathogens from migrating to your newly planted autumn crops. Keep the garden clear of fallen fruit to avoid attracting wasps and rodents.