It’s definitely possible to grow potatoes from your previous year’s crop of potatoes, but be aware that growing potatoes from potatoes you purchase at the store isn’t typically the best method for doing it. Some store bought potatoes will have been treated to inhibit sprouting and growing a plant, and even the organic potatoes that didn’t get this treatment might carry diseases from the previous season. Certified seed potatoes are guaranteed not to carry disease and are therefore preferred.
To grow potatoes from your previous year’s crop, cut a large potato into pieces the size and shape of an ice cube. Each piece should have at least two eyes. For best results, either use sprouted potatoes as seed potatoes or let your potatoes sit in a bright, cold, yet frost-free area (like a porch or sunny window) to grow sprouts before you plant them. In early spring, plant your potatoes at least 12 inches apart in trenches that are four inches deep and spaced three to five feet apart. Cover the seed potato pieces with four inches of soil from the sides of the trenches and water well.
When the sprouts grow taller, continue building hills with soil from the sides of the trenches, but always leave some of the shoots above the soil so they will keep growing. Give your potatoes an inch or two of water each week, watering every four or five days. When flowers appear, increase watering to every two or three days. Potatoes are ready to harvest when their skin has thickened, which should be after the plants have completely died away above the surface of the soil.