How to Harvest Potatoes (and What to Do With Every Spud)

I dug my first potato crop too early, too late, and then too violently with a standard shovel before someone finally told me a garden fork existed. Three years, three different mistakes. If you’re newer to this than I am, consider yourself ahead of schedule.

It’s August in the PNW, which means your main-crop potatoes are either already telling you they’re done or about to start. Learning to read what they’re saying is most of the job.

How to Read the Plant

When the foliage goes yellow and the tops start dying back, that’s not a problem. That’s the plant sending its last bit of energy down into the tubers and calling it a season. Main-crop varieties at that stage have what’s called skin-set, meaning the outer periderm has toughened up enough to actually protect the potato. The periderm is basically a few layers of cork cells that form a moisture barrier. Cool, right? Anyway.

If the skin hasn’t set yet, the tuber will scuff just from sliding against dirt, and that scuff becomes a rot entry point in storage. The test is simple: drag your thumb firmly across the skin. If the skin slips or rubs off, give it another week or two in the ground. If it holds, you’re ready.

New Potatoes Are a Different Conversation

New potatoes don’t need any of that. Any time after your plants flower, you can carefully work a fork into the side of the hill, feel around, and steal a few without disturbing the rest of the plant. No curing, no testing, no waiting. Just rinse them and put butter on them immediately.

My daughters figured this out faster than I did and now treat it like a treasure hunt. Which is fine. We eat well in July.

Harvest Day (Don’t Use a Shovel)

Seriously, use a garden fork. Shovel cuts tubers in half. Fork mostly doesn’t. Mostly. Insert it about a foot away from the stem, angle it under the hill, and lift. Then get down on your hands and dig through the loose soil with your hands because you will find potatoes the fork missed and it is weirdly satisfying.

In late August through September here in the Redmond area, you’ve got a window before the heavy fall rains arrive and start rotting anything still in the ground. Don’t push it. Get them out before October if you can.

Curing: The Part Everyone Skips

Anything you’re planning to store needs 7 to 14 days of curing first. A dark, humid spot around 50 to 60 degrees does the trick. What you’re waiting for is suberization, where cut surfaces and minor nicks heal over with that same cork-like layer. The potato is essentially patching itself. One to two weeks in your garage or a cool shed, spread out in a single layer, is usually enough.

Don’t wash them before curing. Dirt is fine. Wet skin is not your friend here.

The Sorting Decision

After curing, you’ve got three piles to make.

Eat now: Anything the fork nicked, anything with thin skin that didn’t set well, anything forked through the middle. These taste fine but won’t store. Put them in the kitchen this week.

Store: Clean, unblemished, fully cured tubers go in a cool, dark spot at 38 to 45 degrees with decent humidity. A basement corner usually works. Not the fridge. The fridge is actually the one place you do not want them, because cold below that range converts starches to sugars and you end up with weirdly sweet potatoes that go brown when you cook them. Some people like this. Those people are wrong.

Seed stock: Egg-sized tubers from your healthiest plants only. Never save from a plant that showed any sign of disease, because seed-borne potato diseases are not something you want to invite back for next year’s garden. Store your seed potatoes slightly warmer than your eating stock, around 45 to 50 degrees, so the sprout hormones stay dormant but don’t get triggered too early. The dominant dormancy hormone is abscisic acid, which is one of those things that sounds made up but isn’t.

On Saving vs. Buying Seed Potatoes

Saving your own seed potatoes is completely fine when your plants were healthy and you know where they came from. It’s what I do most years and it costs nothing, which as you might have noticed is my preferred price point.

That said, certified disease-free seed potatoes from a reputable supplier are sometimes worth the few dollars, especially if you’re starting fresh, trying a new variety, or had any kind of blight situation last year. They’re tested. Your backyard savings pile is not. Just something to think about before you go full self-sufficient on this one.

The Short Version

Skin slips? Leave them. Foliage is dead? Fork them. Nicked? Eat it this week. Clean and cured? Store it. Egg-sized from a healthy plant? Save it for next spring. And get them out of the ground before the rains hit, because soggy tubers are nobody’s friend.

That’s it. The spud stops here. (Sorry. I couldn’t help it.)

Photo by The New York Public Library on Unsplash