The ethlylene gas given off by an apple will prevent potatoes from sprouting, while keeping onions nearby will actually cause them to sprout. In addition, moisture and exposure to light cause potatoes to spoil, so to keep potatoes fresh for up to 2 weeks, loosely store them in a paper bag. For long-term storage (up to 2-3 months), keep them in a cool, dry, dark place.
Store potatoes with an apple to avoid early sprouting. Keep them away from onions and in a cool, dark place.