Johnny's sells Maine Certified Seed Potatoes. Seed potato certification is a rigorous process that includes field inspections throughout the growing season to check for disease and ensure that varieties are true to type. In addition, a winter grow-out of the seed is done to check for any disease contamination. Organic seed potatoes are produced under strict certified-organic growing methods. See our Potato Comparison Chart to compare distinguishing features such as size, shape, skin and flesh color, storability, and culinary use.