If you have a sweet potato in your pantry that has begun to sprout, don't throw it away. That funny-looking tuber can be turned into a lovely vine. Growing a sweet potato vine is simple enough for a child to do with a little adult assistance. Enjoy the sweet potato vine as a lovely houseplant, or plant it outdoors, where it will grow more sweet potatoes.
Choose a sweet potato that has sprouts. If the sweet potato hasn't sprouted, look for a potato that has several "eyes," which are small bumps where the potato is about to sprout.
Stick four toothpicks into the sweet potato about one-third of the length down from the top of the potato. The toothpicks should be placed equal distance around the potato, like the spikes of a bicycle wheel.
Fill a 1-quart glass jar halfway with warm water and put the sweet potato in the jar. The toothpicks will hold the potato so that one end of the sweet potato is in the water and the other end is above the jar.
Put the jar in a sunny spot, but avoid a sunny window that gets hot afternoon sunlight. Either put the sweet potato 3 to 4 feet away from the window, or put the sweet potato in a window that is shaded by a tree. Filtered light from a curtained window is good, too. The sweet potato needs a minimum of 4 hours of sunlight each day. In about 2 to 4 weeks, the sweet potato should form roots and the beginning of vines.
Give the sweet potato vines a stake or small trellis to climb on, because sweet potato vines are fragile and can break. If possible, leave your sweet potato vine in the kitchen, where it will benefit from the steam and humidity.
Enjoy the sweet potato indoors, or plant it outdoors in May. By autumn, the sweet potato will produce more sweet potatoes that you can dig and eat, or use to start a new sweet potato vine.