Native to the Andes mountains in Peru, the potato (Solanum tuberosum) claims a place as one of the most important vegetable crops grown in the world, according to Iowa State University Extension. They are surprisingly easy to grow and require very little coddling to produce a respectable crop of starchy tubers. Although they produce their edible portion underground, occasionally small, inedible, tomato-like fruits will grow on the above-ground portion of the plants.
Time of Year
Plant potatoes in early spring in eastern Iowa. In the central part of the state, plant them the first or second week of April. In the northern part of eastern Iowa, plant potatoes the second or third week of April. In the southern portion of eastern Iowa, seed potatoes should be planted in the last week of March or first week of April.
Early varieties suitable for growing in eastern Iowa include Irish Cobbler and Norland. Irish Cobbler has white flesh with tan skin and is excellent for baking. Norland produces smooth-skinned rectangular red tubers for boiling or mashing. An excellent mid-season variety for growing in the region is Red Pontiac, a round, red skinned, all-purpose variety, which is recommended by both Iowa State University Extension and the University of Illinois Extension. An all-purpose white potato with tan skin that matures late in the season and is suitable for long-term storage is Kennebec, which is also recommended by both the Iowa State and University of Illinois Extensions.
Because almost all potato varieties do not grow true to their variety from seed, potato plants are started from "seed" potatoes. These are simply 1-inch pieces of cut up potatoes, with each piece containing at least one eye, from which the plant will grow. Seed potatoes should be purchased fresh from reliable suppliers each year. Potatoes carried over from the previous season and used as seed potatoes for a new crop can harbor diseases. Potatoes purchased from the grocery store are treated with a chemical process to discourage them from sprouting and are not suitable for use as seed potatoes.
Potatoes prefer acidic soil of average fertility. A pH below the neutral 7 is ideal, and a pH as low as 5.0 is beneficial to discourage potato scab from developing. Grow potatoes in loamy soil that is neither clay nor sandy. Clay soil is too dense and will inhibit the formation of tubers. Sandy soil drains too quickly and the potatoes will grow knobby and misshapen due to lack of moisture. Do not improve regular garden soil with the addition of manure or compost, a rich soil increases the incidence of the disease potato scab.
Treat cut pieces of seed potatoes with a fungicide immediately after cutting and prior to planting. This will prevent them from decaying in the cool, wet spring soil. A chemical-free method is to store the cut pieces at 60 to 70 degrees for a couple of days in a humid location prior to planting.
Till the soil to a depth of approximately 8 inches, then rake the surface smooth. Plant seed potatoes cut side down, 3 to 4 inches deep, about 10 to 12 inches apart in rows 24 to 36 inches apart. Provide them with the equivalent of an inch of rainfall per week throughout the growing season. The more space between the rows, the larger the potatoes will grow.