680 Solanum tuberosumCommon Names: potato, white potato, Irish potato Family: Solanaceae (nightshade Family)
The potato plant is a leafy, sprawling, almost vinelike annual to 3 ft (0.9 m) tall and spreading out a little more. The compound leaves are about 10 in (25 cm) long and the 7-15 leaflets about 3 in (7.6 cm) long. The tubers are not roots, but modified stems or rhizomes, and the "eyes" are really leaf buds. Potato flowers are rather showy: they are star-shaped, white, lavender, pink or light blue with yellow centers, about an inch across, and borne in clusters. The fruits are like small green tomatoes, about an inch in diameter, and contain several hundred seeds. The fruits, leaves and stems are poisonous.
Home gardeners have many more potato cultivars to choose from than do super market shoppers. The Seed Savers' Exchange maintains more than 600 different varieties of potato. Several commercial seed companies offer a dozen or more varieties. Try 'Lady Finger', an old German heirloom with mouth watering tubers an inch in diameter and 4-6 in (10-15 cm) long; 'Yukon Gold', that looks like it already has butter on it; 'Red Pontiac' a drought tolerant selection good for boiling and popular with commercial growers and home gardeners; or 'All Blue' which is just that with a moist texture and slightly smoky flavor.
The potato, Solanum tuberosum, is native to the Andes Mountains in Chile, Peru and Bolivia. In this region more than 3000 varieties of potatoes have been cultivated for food. The Incas and their ancestors have been growing potatoes for more than 3000 years. Potatoes were first brought to Europe in the early 16th century by Spanish tourists, but did not become a dietary staple until the 18th century. By the early 1800's, most of the people in Ireland were entirely dependent on potatoes for food. In 1845 and 1846 a fungus disease wiped out the entire potato crop in Ireland, and nearly one-half the population starved to death, while a million survivors left for other parts of the world. Today the potato is the most valuable crop in the US, and, behind rice, wheat, and corn, the fourth most important food crop in the world. The Russians lead the world in per capita potato consumption, and 90% of world potato production is in Russia and Europe.
CultureLight: Grow potatoes in full sun. Moisture: Potatoes need well drained soil, but frequent watering. Hardiness: USDA Zones 3 - 10. Potatoes are grown as cool season annuals. They are planted in very early spring, about 2-3 weeks before the last expected frost. (Potato foliage is damaged by frost, but it takes 1-3 weeks before the shoots emerge.) In northern Florida we plant potatoes in January or February. If a late freeze threatens, mulch heavily. You also can take stem cuttings and start new potato plants indoors to put back out when spring weather returns. Even if the foliage is frost damaged, new stems usually will sprout from the seed tuber, especially if it was a large one. Propagation: Potatoes are usually grown from small tubers, called "seed potatoes." These develop into genetically identical clones of the plant that produced the original tubers. Small seed potatoes are planted whole; larger tubers are cut into pieces with 2-4 "eyes" on each piece. It is not necessary to wait for the cut pieces to "heal" before planting. Many gardeners plant their seed potatoes in the bottom of a 6-10 in ( cm) trench and cover with 3-4 in (7.6-10 cm) of soil; as the potato stem and foliage develop, they fill in the trench, burying more of the plant. Others plant potatoes only 1-2 in (2.5-5 cm) deep and cover with a thick layer of hay or straw, adding more mulch as the stem and foliage develop. Either way, burying or "hilling" the lower stems of the potato plant is necessary to keep the developing tubers from becoming exposed and turning green. Always buy certified disease-free seed potatoes because potatoes from the supermarket and tubers from your own garden may harbor diseases that will ruin the crop. Potato breeders and adventurous amateur gardeners grow potatoes from seed. The seed produced by most garden grown potatoes will not come true to type; instead, nearly every seed will produce a plant with different characteristics. Try this yourself: Leave a potato plant in the garden through its flowering period. Collect the small green fruits when they are soft and beginning to fall off the plant. Remove the seeds and macerate in water for 2-3 days before drying. Plant the seeds and cultivate as you would tomato seeds (i. e., start in peat pots at 70º F (21º C), 6-8 weeks before the last frost, then set the plants out in full sun.) If you're lucky, you may produce a potato plant with novel characteristics that you like; if so, you can continue the line by propagating vegetatively with pieces of tubers from your new potato variety.
It's hard to beat new potatoes dug fresh from the garden. You just can't buy these little golf ball-size, skinless, mouth-watering jewels. When your potato plants are about 8 weeks old, carefully reach into the hill and pull out the little tubers one at a time. Do it again in 2-3 weeks. For storage potatoes, wait for about 2 weeks after the tops of the plants have withered and died back, and by then the tubers will have sturdy skins that won't rub off.
Potatoes contain large amounts of starch, vitamins A, B1, B2, C, and K, and several minerals, especially potassium, and are very low in calories. Try cleaning silver with the water that potatoes were cooked in.
Botanists have lumped some 1500 species of herbs, shrubs, vines and trees in the genus, Solanum. Included are important food plants such as potato and eggplant (S. melongena); plants used in herbal medicinal such as nightshade (S. dulcamara); and ornamentals such as paradise flower (S. wendlandii), Jerusalem cherry (S. pseudocapsicum), and potato vine (S. jasminoides). Other familiar plant species among the 2000 or so in the family, Solanaceae, are the tomato (Lycospersicon lycospersicon), tomatillo (Physalis ixocarpa), tobacco (Nicotiana tabacum), sweet and hot peppers (Capsicum spp.), petunia (Petunia spp), Jimson weed (Datura stramonium, and angel trumpet (Brugmansia suaveolens). Many species in the Solanaceae are poisonous.
All parts of the potato plant except the tubers are poisonous. Tubers that have become green are poisonous.
Steve Christman 4/27/00; updated 5/10/03, 8/8/03