For the first five or so years that I was a gardener, I never planted anything in August. It just seems so crazy! It's too hot, how would anything grow? And I don't even really want to be out there right now.
But it doesn't take so long to plant some seeds, and if you just squirt a little extra water at them in the mornings (and maybe the evenings as well) then you might be surprised how nicely some of these plants will grow. Not only will you have fresh salad and another round of sunflowers for the fall, but a lot of these veggies are reasonably frost-hardy and could end up providing fresh produce through February. A handful of the brassicas can even endure a hard freeze; it's quite the delight to have tall plumes of purple and green Brussels sprouts jutting up through the snow!
Try it for yourself and see what I mean. Here's a quick list of vegetables that you can direct-sow (plant right into the ground) in August. Because the North Coast microclimates tend to vary widely and depending on where you live, frost dates can start as early as September or as late as December. I've noted the expected days to maturity in parentheses, so you can plan accordingly and, if necessary, get them in before the average first frost date in your particular area.
The following are not that hardy, but fast-growing and will mature before winter if you get them in right away:
Basil (30-60): Pinch the tops, back to the first node, when the plants are tiny and again a week later, to encourage lateral growth.
Potatoes (80-110): Look for "Irish Cobbler," "Red Norland," "King Harry" and "Caribe." These varieties mature about three weeks faster than others. And don't be fooled by fingerlings! The spuds are small and seem like they'd come on faster, but they actually take longer than large Russets.
Sunflowers (80-120): Check the seed packet to make sure you get a quick variety.
Bush beans (45-65): Bush beans do well in the fall and will die in the first frost but you'll get some snackers before then! Pole beans, not so much.
Nasturtium (40-80): They'll melt in the frost but there's still plenty of time to get some really nice flowers before then. Pickle the green, immature seeds and they're a lot like capers!
Next, some semi-hardy varieties to plant soon, preferably on a south slope or against a south-facing wall:
Peas (70-80): Alderman shelling peas are my all-time favorite, but snow peas do best in fall plantings.
Tatsoi (40-50): Easy, crunchy, frost-hardy and disease resistant salad greens? Yes, please!
Mizuna (40-50): Same as above.
Cilantro (30-60): Personally, I plant cilantro every two weeks from April until November. I just can't get enough of it, and it bolts so fast! Fall plantings in cooler weather are nice, because bolting slows down and the little plants are surprisingly hardy.
Spinach (35-45): Also surprisingly hardy, spinach is best grown in the fall, in my opinion. It yields better flavor and bolts much slower than in spring and summer.
Radishes (30-60): All radishes are easy and fast, but this is an excellent time to plant Daikon radish, in particular, for harvesting throughout the winter.
Loose leaf lettuce (30-60): Lettuce is another plant that I sow habitually, whenever there's a patch of bare soil. It doesn't all make it to maturity, but I always have lettuce when I want some!
Super hardy, and even more delicious after a frost:
Romaine lettuce (30-60): Romaine is just that much hardier than other types of lettuce, and also happens to have a lot more protein!
Beets (50-60): Direct sow in thick patches, then take the time to thin them to three inches apart and you'll be harvesting giant red globes in November!
Onions (60-80): Plant for scallions or roots and harvest all winter.
Parsley (60-110): Did you know parsley is incredibly rich in iron and other minerals? It's also super hardy.
Broccoli and cauliflower (50-90): Days to maturity vary widely, depending which variety you get. In general, brassicas are best grown in the fall. Give them the room they need, water liberally and you will get the ginormous heads you deserve!
Brussels sprouts (80-120): They take a long time to mature, and they need a lot of space, so it makes sense to plant them in late summer/early fall, when summer crops are finished and large spots open up in the garden.
Turnips (50-60): Rich in nutrients for winter stews. Harvest when smaller for a more subtle flavor.
Arugula (30-40): Oh, arugula, how I love thee! So easy and fun to grow with flowers that look like antique lace. Yet another plant that I collect the seed from and toss it around on the daily. Always plant arugula!
Kohlrabi (50-60): Everyone needs to eat more kohlrabi. Try it deep fried. Seriously.
Cabbage (50-90): There's a good reason all those cold places are famous for eating too much cabbage! It grows like a champ all winter long.
Celery and celeriac (90-120 days): If you aren't already growing celeriac, this is the perfect time to try it. Me, I don't like celery. But celeriac? So delicious!
Chard (40-60): Plant a big patch of rainbow chard where you can see it from the kitchen window. To be completely honest, the rainbow variety is not as hardy as good ol' Swiss chard, but those colors!
As always, prepare the ground first — even if you're interplanting with existing plants — to create a successional harvest. Weed the area, then scratch around a little and sprinkle in some nice compost.
The good news about planting in August is that you can be confident that the soil temps are up and your seeds will germinate very quickly. It's much less work than sowing into containers and transplanting, but if you don't keep the seedlings watered while they're getting established, they will die. Cover that base, and you're good to go.
#1: Plant seeds on the edges of areas that are already being irrigated regularly, then just check on them to make sure they're getting enough water.
#2: Soak the seeds overnight first and they'll sprout even faster!
#3: Plant root vegetables in big containers to make harvesting a cinch!
Heather Jo Flores wrote Food Not Lawns, How to Turn Your Yard into a Garden and Your Neighborhood into a Community. Read more of her writing at www.patreon.com/heatherjoflores.