This presentation will help consultants, growers, and other practitioners in potato-growing regions decide when a chloride- or sulfate-based fertilizer is appropriate for fertilization. This presentation will discuss the roles of both potassium and chloride in potatoes. The misconception that potatoes are “chlorophobes” will be addressed, as well as the benefits of potassium fertilization. Historical and recent research will demonstrate potassium effects on petioles and specific gravity.