What Should I Do After Digging Up Sweet Potatoes?

Sweet potatoes (Ipomoea batatas) mature 90 to 100 days after you plant them and will continue to grow until frost kills the vines. After harvest, you need to cure sweet potatoes to protect them from developing diseases during storage. Sweet potatoes are perennial in U.S. Department of Agriculture plant hardiness zones 9 to 11, but are grown as annuals in cooler zones.

Harvesting Them

You can harvest slightly immature sweet potatoes, but it’s best to leave them in the ground until the vines start to yellow. When a frost hits, most of the sweet potatoes will be in soil that is about 60 degrees Fahrenheit. Freezing temperatures won’t damage them unless they’re near the surface of the soil. If a frost hits and you dig them up quickly, they'll store as well as if you had dug them before the frost.

Curing Them

If you cut or bruise sweet potatoes when you dig them up, they’ll release a sticky, milky juice that will dry in a few hours. Although the wound may appear to heal, if you store injured sweet potatoes immediately, they may develop fungal rots. To heal bruises and wounds and seal out rot fungus, cure them before storing by keeping them for 10 to 14 days in a dark, humid place at 80 to 85 degrees F.

Storing Them

Sweet potatoes store best at temperatures of 55 to 59 degrees F with relative humidity at 60 to 75 percent. An unheated basement or root cellar is a good place to store them, or wrap them in newspaper and keep them in a cool closet. Chilling temperatures can injure them, so don’t store them in a refrigerator. You can expect sweet potatoes to retain their quality for six to 10 months, but some cultivars may begin sprouting after six months. They will taste better if you give them a minimum of three weeks in storage to allow their starch to convert to sugar before you eat them.

Making Sweet Potato Mounds

If you live in an area with mild winters, it’s possible to store sweet potatoes in outdoor mounds. Pile cured sweet potatoes in a 3- to 4-foot-tall cone or pyramid on top of 8 to 10 inches of wheat straw. Pack a thick coat of straw over the mound. Top the straw with 2 to 3 inches of soil. To keep rain from washing away the cover, stack boards around the pyramid and fasten them at the top. To retrieve sweet potatoes, dig carefully into the mound and remove as many as you need. Rain can cause some sweet potatoes to rot when they're stored in mounds.

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