Sweet potatoes (ipomoea batatas) belong to the morning glory family (Convolvulaceae). Native to Central and South America, they were cultivated five thousand years ago and spread around the world like wildfire. Their worldwide expansion is due, in part, to the fact that sweet potato plants grow really well in a lot of places — they do all right basically anywhere that doesn’t get very cold, and they thrive in a tropical or subtropical climate.
Sweet potato plants give a lot and require very little. They actually improve the soil, and their lush vines shade out noxious weeds. They’re reliable and produce generous crops, even in poor soil with little rain and high heat. No wonder they became popular everywhere they could grow.
The other, and most obvious, reason for the sweet potato’s worldwide fame is that they’re delicious, and versatile. Sure, they’re purportedly full of nutrients and are super good for us, but if none of that were true, they’d still be a favorite.
In season: Late fall through early spring
Origin: Native to Central and South America, but cultivated around the world
Varieties: Hundreds, but most fall into dry (white or purple flesh) and not-so-dry (orange flesh). Also, yams are NOT sweet potatoes.
How to cook: Bake, boil, steam, or roast
When Are Sweet Potatoes in Season?
Grocery stores have sweet potatoes all year long. Sweet potato season according to nature and your local farmers is late fall through early spring, but it’s a little more complicated than that.
They’re harvested around the beginning of fall, but it takes several weeks before they’re good and ready to go to market because sweet potatoes require curing. “Curing” means that after harvest, they’re stored away and left to develop all the characteristics we love about them — the sweetness and the textures depend on curing time. This time also makes them better at long-term storage; it’s why they’re able to stick with us all the way through winter and into spring.
Different Types of Sweet Potatoes
There are hundreds of varieties of sweet potato available in the US, and several thousand varieties worldwide. I find that thrilling — all the different colors, shapes, sizes, textures, places of origin, ages of varieties and cultivars! — but trying to break that down and categorize and make sense of the whole sweet potato family is beyond me.
All the sweet potatoes available here are sweet, earthy, a little nutty, and a little bitter in the skins. Some are slightly sweeter, and there are variations in color, but the big defining difference is texture. We have two categories: The Dry and The Not-So-Dry.
As a general rule, sweet potatoes with white or purple flesh are dry.
Their flesh feels dense and starchy, like sweet potato mixed with Russet — equal parts of each. Anything with orange flesh is not-so-dry. They’re more tender, kind of silky, and can get stringy (dry can’t do that).
We Need to Talk About Yams
The yams we see in stores — the Jewels and the Garnets — are not yams; they’re sweet potatoes. And yams aren’t grown in the States. Yams are native to Africa. They’re big, starchy, and really hard to grow and harvest.
Know how sweet potatoes need to cure for several weeks? Yams require up to a year to mature. There are so many more differences, but you get the point. Not the same. Not interchangeable. They don’t even belong to the same plant family (yams are Dioscoreaceae).
How did this mix-up happen? On purpose! It was totally intentional. The white-fleshed sweet potato used to be the most common in America. In the mid-20th century, marketers decided that the soft orange-fleshed sweet potato needed a name to set it apart. Somehow, calling them orange sweet potatoes and white sweet potatoes wasn’t satisfactory differentiation. We could have used the names of their individual varieties (their proper names!), but no. They went with Yam.
What’s in a name? In this case, gross mislabeling, unnecessary confusion, and slavery. Yam was taken from “nyami,” the African word for yam, which is the word slaves used for sweet potatoes because they resembled the yams from back home. This name gave sweet potatoes a new identity as an entirely different species. (Somebody please make all of this make sense, because I really cannot.)
The USDA now requires these to be labeled as yams and sweet potatoes, so the identification is only half incorrect. Progress, I guess? There is no reason for mislabeling when we know what’s what, so let’s all use the right names from now on.
How to Pick a Good Sweet Potato
You want sweet potatoes that are firm and have smooth skin. Avoid anything with signs of sprouting, lots of wrinkling, dark or soft spots. If they feel at all spongy when you squeeze them, pass.
Some sweet potatoes can get very big. A sweet potato that’s 12 inches long and super heavy (for a potato) is amusing, but I wouldn’t bring it home. For the best texture and flavor, and an easier time cutting the thing, stay on the small-to-reasonable side of the size spectrum.
How to Store Sweet Potatoes
If they had their druthers, sweet potatoes would hide away in a root cellar, where it’s dry, dark, and about 50° F. In a place like that, they’d keep for months. I don’t know about you, but I don’t have a root cellar, so we’ll just do our best.
Sweet potatoes don’t like to be cold or damp, and they don’t like to be in warm places, so keep them out of the fridge and away from a lot of light, and hope that they find your room temperature agreeable — too hot or too cold will make them shrivel and sprout.
Preserving Sweet Potatoes
Cooked sweet potatoes can be frozen very easily. Whole, sliced, cubed, pureed — however you like, just let them cool completely. Transfer them to a freezer bag, remove as much air as possible, seal the bag, and store away.
They can also be canned, if that’s your preferred method of preservation.