Potatoes should be planted in soil that is loose and well-draining. Dig a trench or furrow that is about 6 to 8 inches (15 to 20 centimeters) deep. Place the seed potatoes in the trench, spaced about 12 to 15 inches (30 to 38 centimeters) apart. Cover the potatoes with soil, leaving a small mound or ridge on top. As the plants grow, gradually add more soil around the stems to protect the developing tubers from sunlight and promote more potato growth.