Potatoes are ideal for fall planting in southern United States climates, since they can quietly slumber as tubers underground all winter and take advantage of every bit of sun and rain in the spring so you get early potatoes the next season. Plant seed potatoes in the fall after you harvest your other fall crops. Unfortunately, fall potato planting is not successful in northern climates where the ground freezes solid in the winter. It is best to plant seed potatoes in the fall in zones 6 and warmer.
Add compost to the soil where you plan to plant the potatoes. This is especially important if it is an area where you previously harvested a fall crop, since the soil is likely to be stripped of many nutrients.
Cut the seed potatoes into small pieces that are about 1 to 2 oz. each. Make sure each piece has at least one eye, as this is where the new sprout will form. Allow cut pieces to heal for two days before planting. For the best results, use small, whole seed potatoes.
Dig 10 inch deep ditches on either side of your potato row, packing the dirt up between the ditches for a hilly ridge of good soil. Creating a hill lined by ditches for fall potato plantings keeps them from standing in wet soil throughout the winter, which leads to rot.
Plant the seed potatoes in a furrow inside the dirt ridge, spacing them about 1 foot or 10 inches apart. Cover the seed potatoes 1 to 3 inches deep with soil. Space additional rows between 2 and 3 feet apart to let the plants grow fully the next year.
Mulch around and over the potatoes, completely covering the top of the furrows. This adds an extra layer of frost protection and an extra layer of organic matter to enrich the spring soil.