August Seed Starting in the PNW: Don’t Skip Fall

Everyone talks about starting seeds in March. I get it. The seed catalogs show up in January when it’s grey and wet and you’ve been staring at dormant garden beds for four months. But August? Most people are in harvest mode, maybe canning something, definitely not thinking about seeds again.

That’s a mistake. August is the second seed-starting season in the Pacific Northwest, and honestly it’s one of my favorites. The soil is warm, germination is fast, and you’re setting yourself up for fresh food well into winter. I skipped this window for years before I figured out what I was missing.

Why Fall Planting Works So Well Here

We don’t get hard freezes in Redmond until pretty late in the year, and even then it’s inconsistent. That mild shoulder season is a genuine advantage. A lot of cold-tolerant crops need that gradual cool-down to really perform, and the PNW basically hands it to you for free.

And here’s the part that made me feel like I was on a cooking show for a second: cold temperatures actually trigger plants like kale and spinach to convert starches to sugars, a stress response that acts like antifreeze. Which is why fall-planted kale tastes noticeably sweeter than the stuff you harvested in June. There’s actual chemistry happening out there. Anyway.

Greens to Direct Sow Right Now

Kale and chard both go in now, direct sow or transplant, and they’ll establish before the rains come back in earnest. Kale especially gets better every time it frosts. I just scatter the seeds, rake them in lightly, and mostly leave them alone. These are not fussy plants.

Spinach is one of those crops that genuinely prefers cooler soil for germination, ideally below 70 degrees. Germination tanks above 75, so late August into September is actually the sweet spot here. Soil temps have dropped just enough to get good sprout rates without babysitting it. Direct sow spinach into a bed you’ve just cleared of summer stuff, keep it moist for a week or so, and it practically does the rest.

Lettuce for fall harvest goes in now too. I usually start these in small containers and transplant after about three weeks, mostly because slugs will annihilate tiny lettuce seedlings if I’m not careful. One lesson I keep re-learning every single year.

The Radish Situation

Fall radishes are wildly underrated. Not the little Easter egg radishes you plant in spring that bolt if you look at them sideways. I’m talking about daikon types or fall-specific varieties that size up fast in cooling soil. You can go from seed to harvest in under 30 days with some of them. My daughters will actually eat radishes if they helped pull them out of the ground, which is its own kind of miracle.

Asian Greens Are Built for This

Tatsoi, pak choi, mizuna. If you haven’t grown these, August is the time to start. They bolt almost immediately in summer heat, but in cool weather they are genuinely unstoppable. Mizuna especially looks like it’s trying to take over the bed by October, which is exactly what you want. Direct sow all of these, thin generously (I always thin too lightly and regret it), and harvest outer leaves as you go.

I pick up a cheap packet of mizuna seeds from the seed rack at the garden center every year. One packet lasts me two seasons easy.

Late August: Cover Crops

Once you hit the last week or two of August, start thinking about cover crops for any beds you’re winding down. Crimson clover, hairy vetch, winter rye, and fava beans are all good options here. Favas pull double duty since you can actually eat them in spring, which, if you think about it, is just a cover crop that pays rent.

The legumes like clover and vetch host rhizobium bacteria in their root nodules, which fix atmospheric nitrogen into a form your soil can actually use next season. One sentence of biology, I promise that’s all. The practical takeaway is that you’re building next year’s fertility for basically nothing. Winter rye is the cheap workhorse option, inexpensive by the pound and you seed it pretty thick. I usually grab a small bag from the feed store rather than the garden center. Same seed, fraction of the price.

A good fall cover crop mix is worth keeping on hand if you don’t want to buy four separate bags.

What to Start Indoors Right Now

If you want to get a little head start on transplants, start kale, chard, and pak choi indoors in early August and move them out in three to four weeks. I use coconut coir for seed starting mix because it’s cheap and consistent. Nothing fancy required. Yogurt cups with holes poked in the bottom work fine. I tried those little peat pellets one year and they dried out constantly and I lost half my starts. The coir just behaves better. Kale in particular doesn’t care at all what container you use. The plants have no ego.

The Short Version

Clear a bed, scratch in some seeds, and don’t sleep on this window. Spinach and kale planted now will taste better in November than anything you grew in May. That’s not motivational poster stuff. That’s just sugar chemistry being on your side for once. You’ve really got nothing to lose, except maybe another season of staring at empty beds. So.

Lettuce get planting. (Couldn’t help it. Sorry.)

Photo by Sandie Clarke on Unsplash