As a good rule of thumb, plant potatoes in Central Iowa Easter weekend. Potatoes can handle light frosts and cool soil temperatures, and planting early will provide a crop of tender new potatoes in late June or early July.
To prepare your seed potatoes for planting, set them in a bright area with temperatures between 60-70 degrees F. This will begin the sprouting process. About two days before planting, cut the seed potatoes into smaller pieces using a clean, sharp knife. Be sure each piece contains at least one eye or sprout. There is no need to cut potatoes that are smaller than a golf ball – just plant those whole.
Leave the seed pieces on a tray or sheet so they are exposed to air – the garage or kitchen counter both work well. The seed pieces will develop a thick callous over the cuts, which will help prevent rot once the seeds are in the ground.
Choose a sunny spot with well-drained, loose soil. If your soil is compacted, turn the soil in the area you will plant potatoes. Potato plants should be rotated every year. Do not plant where potatoes, tomatoes, peppers, eggplants, or strawberries have been grown in the past 4-5 years.
Plant each piece of seed potato cut side down (eyes or sprouts pointing up) every 12-15 inches, in rows 3 feet apart. Cover with about 4 inches of loose soil.
Water your newly planted potato seeds and keep the plants well watered, but not soggy. When the potatoes begin to grow, continue to add soil, mounding around the plants as they grow.