Plant potatoes from late winter to late spring–as early as 4 to 6 weeks before the last average frost date in spring–depending upon the number of days the variety you are planting requires to mature to harvest. So-called “early” potatoes will come to harvest in summer; “midseason” and “late” potatoes will mature and come to harvest in fall.
Description. The potato is a perennial vegetable grown as an annual. It is a weak-stemmed plant that produces swollen, underground tubers that are usually oval or round but sometimes finger-like or clustered. Potatoes can be brown, tan, yellow, red, and purple. Potatoes grow best where nights are cool. Potato varieties are often classified according to the number of days they require to come to harvest: “early” season (75-90 days), “midseason” (90-135 days), and “late-season” (135-160 days).
Yield. Each plant will produce about 5 to 10 potatoes.
Site. Plant potatoes in full sun. Potatoes require a cool but frost-free growing season of 75 to 135 or more days. The ideal potato growing temperature is 45° to 80°F. Hot weather will reduce the number of tubers per plant. Potatoes prefer well-drained fertile soil high in organic matter with pH of 5.0 to 5.5. As the soil becomes more alkaline the size of the crop will grow but the incidence of scab–a condition that affects the skin of the potato but not the eating quality–also will increase.
Planting time. Plant “early” potatoes in spring 4 to 6 weeks before the last average frost date for a summer harvest or when the soil temperature has risen to 50°F. Where the soil temperature does not rise above 85°F during the summer plant “early” potatoes in late spring. Plant “midseason” harvest potatoes 4 to 6 weeks before the last frost in spring for fall harvest. Plant “late” harvest potatoes in spring for fall harvest. Allow 120 frost-free days from planting to harvest for “late-season” varieties. Potatoes are grown through the summer in cool northern regions; they are grown in fall, winter, and spring in warm-winter southern regions.
How to plant and spacing. Grow potatoes from whole potatoes or pieces of potatoes called “seed potatoes.” A seed potato must have at least one eye to sprout. Plant certified disease-free seed potatoes. Supermarket potatoes have been chemically treated to prevent sprouting.
Plant potatoes in a hole or trench 4 inches deep and cover with 2 inches of soil. When sprouts emerge, add the remaining 2 inches of soil to the hole or trench. Sow seed potatoes 12 to 18 inches apart; space rows 24 to 36 inches apart. Potatoes also can be planted on top of the ground if covered with a 12-inch thick mulch of straw or hay.
Potatoes also can be grown in special potato growing barrels or stacked old tires. As the plant grows, layers of soil are added to cover the leaves and stems encouraging the plant to produce new tubers.
Water and feeding. Keep potatoes evenly moist but not wet; water before the soil dries out. Mulch to conserve soil moisture, prevent the soil from becoming too warm, and to keep the weeds down. Feed potatoes with a 5-10-10 fertilizer before planting and as a side dressing at midseason. Avoid giving potatoes too much nitrogen, that will encourage foliage growth over tuber growth.
Companion plants. Beans, cabbage, corn, eggplant. Avoid planting potatoes near cucumbers, pumpkins, squash, sunflowers, tomatoes, or raspberries.
Container growing. Potatoes can be grown in special potato barrels or using several car tires. Plant seed potatoes in the first level of a barrel or tire. When vines grow from 8 to 10 inches tall, place a second tire or level over the first and add enough soil to cover all but 2 or 3 inches of the vines. Continue this process until the end of the growing season. Then harvest potatoes from each layer.
Care. Protect maturing tubers from sunburn and greening by mounding soil up around exposed tubers. Carefully cultivate around plants until they flower.
Pests. Potatoes can be attacked by Colorado potato bugs, leafhoppers, flea beetles, and aphids.
Diseases. Potatoes are susceptible to blight and scab. Scab can cause potatoes to have a rough skin but does not affect the eating quality of the potato. Plant disease-resistant varieties and keep the garden clean to help prevent disease. Remove and destroy diseased plants.
Harvest. A potato plant will produce 3 to 6 regular-size potatoes and a number of small ones. Use a spading fork to dig up new potatoes when flowers fade; harvest mature potatoes after the leaves start to yellow. Lift potatoes gently to avoid bruising or damaging the skins.
Varieties. There are more than 100 varieties of potatoes. There are four basic potato categories: long whites, round whites, russets, and round reds. Check your cooperative extension service for specific recommendations for your area.
Storing and preserving. Store potatoes in a dark, well-ventilated place at about 40°F. Potatoes will keep for about 6 months. Do not refrigerate potatoes. Prepared or new potatoes freeze well and potatoes can also be dried.
Common name. Potato, white potato, Irish potato
Botanical name. Solanum tuberosum
Origin. Chile, Peru, Mexico