According to an article I read on gardners.com, you can let it get killed back by a frost, then cut it back and store it, pot and all, in a cool dark place between 40 and 50 F for the winter. It also says you can dig and store them in moist peat moss in black plastic bags like dahlias, but I did not have success with that method last winter. It could be the tubers dried out on me, because I didn't check on them in the basement. The dahlias stored the same way were fine this spring.

Good gardener friend and Purdue hort site agree that sand is the way to go.

The sand can be misted to avoid dryout, but doesn't hold moisture next the roots to make them rot the way misting peat would. (Not the best wording but I'm not sure how else to describe it.)

She has several different varieties that have successfully overwintered this way.

Also note that friend kept plants in a cold greenhouse.

Martie

Here is a link that might be useful: Cultivation and Harvest of Ipomoae batatas (Purdue)

That's a great idea about the sand, Martie.

I've had good results overwintering the tubers dormant in a fairly warm basement--about 65*F. The first year I tried this, I dug out the tubers and tossed them in a pot, dry, much like one of the posters to this question on the Bulbs Forum did. They were just fine, if a little dessicated, when I put them back into the ground in spring. In subsequent years, I've taken the tubers inside in their pots, once top growth has died back in fall, and overwintered the tubers in the pots, totally dry. This works well for me.

What has never worked for me is trying to grow them inside the house, even for just a few weeks at the beginning or end of their growing season. 'Marguarita' (sp?) hated my chilly house and did its "I'm cold and wilty" thing until it died (or I tossed it--can't remember). 'Blackie' first turned green (despite being in strong light) and then developed the worst, most persistent aphid infestation I've seen in a long time. The bronze one--sorry, I'm blanking on its name right now--just kind of melted away, never to be seen again. However, last winter, I overwintered cuttings of 'Blackie' in water. They did fairly well, despite being green and losing most of their leaves, but the dormant tubers are easier, and, in my experience, always in better health when spring finally comes around. I don't start mine early indoors, needless to say.

Good luck.

Amanda

Thanks to all.
I have 6 large tubers and will try both methods, in dry pots with soil and exposed dry (as I do with begonias) and see how it works.
In any events I have nothing to lose, they are readily available in a spring.