What to Plant in August in Southern California for a Fall Harvest

Written by Susan B.

In Southern California, late summer is not the end of the gardening year, it is the start of the cool-season fall garden. From August into September you can set out brassica transplants, direct-sow fast greens and root crops, and squeeze in the last warm-season beans along the coast.

Vegetable	Plant in (late summer / fall)	Seed or transplant	Days to harvest	Notes
Broccoli	August (seed) into September; transplants September on	Seed or transplant	60 to 100	Interior valleys can sow July
Cauliflower	July to September	Seed or transplant	60 to 100	Interior valleys July to August
Cabbage	August (coastal), July (interior)	Seed or transplant	60 to 100	Long coastal window
Kale	August to September	Seed or transplant	50 to 70	Very frost tolerant
Brussels sprouts	August to September	Transplant (best)	90 to 120	Grows best near the coast
Carrots	August to September	Direct sow seed	60 to 80	Keep seedbed moist
Beets	August to September	Direct sow seed	50 to 70	Thin seedlings for full roots
Radishes	August to September (coastal nearly year-round)	Direct sow seed	25 to 35	Fastest crop; thin seedlings
Turnips	August to September	Direct sow seed	40 to 60	In the brassica family
Rutabaga	July to September	Direct sow seed	80 to 100	Slower and more finicky
Lettuce (leaf or head)	August to September	Direct sow seed	30 to 60	Needs light to germinate, do not bury seed
Spinach	August to September	Direct sow seed	40 to 50	Long coastal window
Swiss chard	August to September	Seed or transplant	50 to 60	Long coastal window
Arugula	August to September	Direct sow seed	30 to 40	Fast leafy green
Peas	August to September	Direct sow seed	60 to 70	Cool-season
Beans (bush, pole, lima)	July into August (last window)	Direct sow seed	50 to 70	Warm-season; finishing, not starting
Cilantro, dill, parsley	July to September	Direct sow seed	30 to 70	Parsley slow to germinate

What to Plant in August vs September in Southern California

In August, set out brassica transplants (broccoli, cauliflower, cabbage, kale, and Brussels sprouts), direct-sow heat-tolerant fast crops (radishes, arugula, carrots, beets, and leaf lettuce), and get in the last planting of warm-season beans along the coast. Starting slower brassicas as transplants now gives them a head start toward a fall harvest, while the fast crops you sow from seed fill in quickly. These windows follow the UC Master Gardener Time of Planting table for the South Coast and Interior Valley.

September is the broad cool-season wave. Keep sowing greens (spinach, lettuce, and chard) and root crops, add peas, and set any remaining brassica transplants. In mild coastal zones you can keep succession-sowing greens and radishes well into fall, which is why the UC Master Gardeners of San Diego County planting guide leans toward September for most cool-season crops near the coast. For a look further down the calendar, see our companion guide on what to plant in your SoCal garden this fall and winter.

Growing Vegetables in Southern California

Our Southern California climate makes it possible to grow vegetables all year. Unlike many parts of the country where there is a limited growing season and planting times revolve around the first and last frost dates, our ability to grow things all year means we rely on a calendar laid out in the California Master Gardener Handbook. That is why late summer, rather than being a wind-down, is actually the perfect time to think about planting for a fall harvest.

How you start each crop matters. If you are planting seeds, look at the package to find out how long the seeds take to germinate and how long until harvest. You can direct-sow vegetable seeds for crops you want to harvest in late summer or fall, and root crops and leafy greens do best this way because they do not transplant well. Slower brassicas like broccoli, cauliflower, cabbage, and Brussels sprouts commonly go in as transplants in late summer so they have time to mature before winter. Since we stock our stores with seasonal offerings, you will have no trouble finding seeds or starter plants for your late summer vegetable garden.

Late Summer Planting of Brassica Vegetables

Brassicas are the backbone of the SoCal fall garden, and most of them go in best as transplants in late summer so they mature before the cool, short days of winter. The timing below follows the UC Master Gardener monthly planting windows.

Cabbage

For areas along the south coast, plant cabbage in August. In the interior valley areas, plant cabbage in July. Transplants give you a faster, more reliable fall head.

Chinese Cabbage

Areas along the California southern coast should plant Chinese cabbage in August and September. For communities in the interior valley, plant Chinese cabbage in August. It can be started from seed or set out as a transplant.

Cauliflower

Residents of areas along the Southern California coast should plant cauliflower in mid-to-late July, or in August or September. Residents of the interior valley areas can plant cauliflower in July or August. Setting out transplants is the easiest way to get a dependable head by fall.

Kale

In areas that lie along the Southern California coast, plant kale in August and September. Plant kale in August and September if you live in the interior valleys as well. Kale is very frost tolerant, and it transplants readily, so you can set out starts or direct-sow seed.

Kohlrabi

We doubt many home gardeners regularly plant kohlrabi, but if you do, or if you would like to, plant it in August or September in areas lying along the southern coast. Plant it in September if you live in the interior valley area. Transplants or direct-sown seed both work.

Mustard

Mustard greens are a southern staple, but that does not mean Californians cannot plant them in their home vegetable gardens. They are packed with nutrition, and they are as versatile a side dish as spinach, Swiss chard, or kale. We encourage you to grow a variety of nutrient-rich vegetables in your garden, especially if you have the space. Direct-sow seed in August and September if you live in southern coastal areas, and in September if you live in the interior valleys.

Radishes

In areas along the Southern California coastline, gardeners can plant radishes nearly all year long. September is the time to plant them if you live in the interior valleys. Direct-sow radish seed right in the ground. Do not worry about spreading the seeds out evenly, because you will thin the seedlings after they sprout. At roughly 25 to 35 days, radishes are the fastest crop in the fall garden.

Turnips

It never occurred to us that turnips could belong to any class other than root vegetables, but the turnip is part of the brassica (or cruciferous) family. They are more versatile than you might think. You can mash turnips, rice them, roast them, or add them to a soup. Direct-sow seed in August or September in our southern coastal areas. In the interior valleys, August is the time to sow turnips for a fall harvest.

Late Summer Root Vegetables

Root vegetables are versatile because you can cook them in a variety of ways and use them in soups or as side dishes, either roasted or pureed. Because roots do not transplant well, direct-sow them right where they will grow. Celeriac (celery root) belongs here too: it is a member of the carrot and parsley family (Apiaceae), not the brassicas, and it is sown in July and August along both the south coast and the interior valleys.

You can plant beets, fennel, onions, and leeks in August. Sow carrots and parsnips from seed in August or September, and keep the seedbed moist since both are a bit more challenging to grow. Rutabaga, which is also slower and more finicky, can be direct-sown in July, August, or September. In our mild climate, you can grow green onions all year long. If you want to grow white potatoes, plant them in July and August in southern coastal regions, and in August in the interior valleys. A feeding partway through the season helps roots size up, so review our guide on how and when to fertilize your vegetable garden.

Late Summer Beans and Peas

Beans are a warm-season crop, so late summer is about finishing their season, not starting it. Along the coast, July into August is the last good window to direct-sow bush beans, cowpeas, and lima beans for a harvest before the weather cools. Pole beans work the same way but are a little more challenging to grow. Sow them from seed, give them warmth, and expect them to wrap up as fall arrives.

Peas, by contrast, are a true cool-season crop and fit the fall garden perfectly. If you live in a community along our southern coast, direct-sow peas in August and into September for a steady fall harvest.

Late Summer Annual and Biennial Herbs

If you want to keep cutting fresh herbs through late summer and into fall, plant basil, cilantro, dill, and parsley in July and August. Most of these are best direct-sown, and parsley in particular is slow to germinate, so be patient. Keep in mind that dill seeds scatter quickly in the wind. If you do not want dill to spread uncontrollably, grow it in a container or in a spot away from your other plants and herbs.

Late Summer Perennial Herbs

Perennial herbs come back every year, so once you plant them you can harvest for many seasons to come. For a late summer and fall harvest, plant anise-hyssop, borage, comfrey, lavender, oregano, sage, and thyme in July and August. Many of these establish most reliably from transplants or divisions rather than from seed.

Fast-Growing Leafy Greens

When we mention fast-growing leafy greens, we are talking about vegetables ready to harvest in anywhere from three to seven or eight weeks. Those greens include arugula, chicory, lettuce, mesclun mix, spring mix, and lettuce blends, in either baby or full-size varieties. Direct-sow arugula, lettuce, and other leafy green seed right in the ground. Wet the soil before you plant so the seeds do not wash away. Do not cover lettuce seeds with soil after scattering them, because lettuce seed needs light to germinate. These quick crops are a great way to plant late in the season and still get a harvest.

Slow-Growing Leafy Greens

Slow-growing leafy greens take longer to mature than their faster-growing relatives, but they reward the wait with hearty, nutrient-rich leaves. This group includes collards, Swiss chard, and spinach. Direct-sow or transplant these in August or September for a fall harvest. If you want to see what cool-season starts are available, you can browse cool-season vegetable starts in our plant library.

Southern California Late Summer Planting FAQ

What should I plant in August in Southern California?

In August, Southern California gardeners can set out transplants of broccoli, cauliflower, cabbage, and kale, and direct-sow fast crops like lettuce, arugula, radishes, carrots, and beets for a fall harvest. August is also the last good window for warm-season beans along the coast.

What can I plant in late summer in SoCal?

Late summer is ideal for cool-season vegetables. Along the coast you can plant brassicas (broccoli, cauliflower, cabbage, kale, Brussels sprouts), root crops (carrots, beets, radishes, turnips), leafy greens (lettuce, spinach, chard, arugula), peas, and herbs like cilantro, parsley, and dill.

Is it too late to plant vegetables in late summer?

No. In Southern California’s mild climate (USDA zones 9b to 10b), late summer is actually the start of the cool-season planting window, not the end. Most cool-season crops can be planted from August through September, and many greens and root crops can go in even later along the coast.

What vegetables grow in fall in Southern California?

Fall is the sweet spot for cool-season crops: broccoli, cauliflower, cabbage, kale, Brussels sprouts, carrots, beets, radishes, turnips, lettuce, spinach, Swiss chard, arugula, and peas all thrive in SoCal’s mild autumn.

What is the fastest vegetable to grow for a fall harvest?

Radishes are the fastest, ready in about 25 to 35 days from seed. Arugula and leaf lettuce follow close behind at roughly 30 to 40 days, which makes them great choices if you are planting late in the season.

Should I plant from seed or use transplants in late summer?

Use transplants for slower brassicas like broccoli, cauliflower, cabbage, and Brussels sprouts so they mature before winter. Direct-sow root crops (carrots, beets, radishes, turnips) and leafy greens (lettuce, spinach, arugula), since they do not transplant well.

Sources:

• UC Master Gardener Program, Time of Planting
• UC Master Gardeners of San Diego County, Vegetable Garden Planting Guide
• UC ANR Publications, California Master Gardener Handbook

Start Your Fall Garden at Green Thumb Nursery

Late summer is the moment to get your cool-season crops going, and we are here to help you do it right. Stop in for cool-season seeds, healthy brassica and leafy-green transplants, and advice from our garden experts on timing, soil, and watering for a bountiful fall harvest. Our inventory shifts with the season and with customer demand, so there is always something new to start. Find hours and directions and visit a Green Thumb Nursery near you.

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