Sweet potato vines react poorly to cold temperatures, and you must prepare them for winter if you want to replant in the spring. To preserve your plant throughout the coldest of temperatures, you have some options, depending on the location of your sweet potato vine. As annuals, expect your vines grown outdoors to die, but by saving the tubers, you can effectively winterize the sweet potato vine's genetic material for replanting in the spring.
Bring a container in which a sweet potato vine grows inside following the first frost. Set in a dark spot, misting it once a week to maintain soil moisture throughout the winter. Move the pot outside after the last frost into a sunny location.
After the first frost of the year, dig up the tubers out of the ground and cut off their stems.
Rinse off the tubers and wrap each with lightly dampened newspaper, storing several in a black plastic garbage bag. Alternatively, fill a plastic garbage bag with peat and bury the tubers in it without wrapping them in newspaper.
Set the garbage bag in a dark spot that maintains temperatures of 40 to 50 degrees Fahrenheit. Spray the exterior of the newspaper or the peat with the mister once a week to keep the storage medium moist.
Re-pot or replant your stored sweet potato tubers after the last frost.