saving sweet potato tubers
Instead of buying new sweet potato vines every year, try saving the tubers. Carefully dig the tubers, as the skins of freshly harvested sweet potatoes are delicate. To toughen their skins, lay them between layers of newspaper in a warm, dry area, like the top of the refrigerator, for two weeks. Then, store them in an open box, with a layer of dry sawdust or sphagnum moss on top, in a cool (55 to 60 degrees), dry, dark place. A heated garage or basement works well. Check the tubers periodically and remove any that become soft and mushy. Tubers can be stored for several months.
In spring, propagate new vines by burying three-fourths of the potato, pointed end down, in a pot of moist sand. Put the pot under fluorescent lights on a heat mat set at 75 to 80 degrees. Sprouts will develop; when they reach about 5 in. long, pinch them off the tuber and pot them up in potting soil. Grow the sprouts under the same lights until the threat of frost has passed, then move the small plants outside.