Annual Red Pontiacs (Solanum tuberosum 'Red Pontiac'), popular with home gardeners, are round to oblong potatoes with thin, red skins and white flesh. Each plant should yield between 3 to 5 pounds of potatoes that will mature in about 80 days. If you plan to plant them the recommended 12 inches apart, you need about 5 pounds of seed potatoes for a row 40 feet long.
Buy seed potatoes that are certified to be free of disease from a nursery or garden supply that you trust. Many supermarket potatoes have been treated to prevent them from sprouting, and potatoes that you’ve grown yourself may carry diseases.
Where to Plant
Red Pontiacs need full sun and thrive in sandy soil. Soil with a pH above the 5.5 to 6 range increases the incidence of potato scab forming on the skin. To avoid plant diseases, do not grow Red Pontiacs in a spot where you have grown potatoes during the last three to four years. Plant potatoes when the soil temperatures exceed 45 degrees Fahrenheit.
How to Plant
Cut the seed potatoes into pieces about 2 inches wide or about the size of golf balls, each containing one or two buds, or dimples, called eyes. Red Pontiac potatoes have numerous eyes. They are also small potatoes. Some are small enough that you may be able to plant one potato by itself.
To prevent the seed pieces from rotting in cool, wet soil, store them for several days at a relative humidity of 85 percent and a temperature of 60 to 70 F. This allows a protective callus to form on the cut surfaces.
Cultivate the soil 6 to 8 inches deep in the spring, breaking up large clods. If you have not had your soil tested to see whether it has special needs, work about 2 pounds of 12-12-12 of granular, water-soluble fertilizer into the top 6 inches of 50 feet of row using a rototiller or spade.
Plant the seed pieces 3 to 4 inches deep with the eye side facing up. For maximum yields space them 9 to 12 inches apart in rows 30 to 36 inches apart. Keep the soil moist but not soggy while the plants get started.
Potatoes develop from the growing stems. Exposure to the sun may turn them green and make them taste bitter. To prevent greening and to increase yield, use a garden hoe to mound the soil 3 to 6 inches high around the stems, about 12 to 15 inches from the plant base, repeating as the stems grow. This is called hilling.