Originally created 01/26/01

Potatoes require work to grow well locally



Irish potatoes have an interesting history. In the 1500s Spanish explorers took potatoes to Europe from the Peruvian Andes. Europeans were slow to accept them because they belong to the nightshade plant family, which has many poisonous members. Once accepted, though, potatoes quickly became a staple crop, particularly in Ireland, where the rich soil and cool climate are perfect for growing them.

In 1845, late blight struck, wiping out the crop for two years. During the subsequent famine, 750,000 to 1.5 million people starved. Ireland's population fell more than 8 million to fewer than 5 million, and more than 1.5 million people emigrated to the United States.

Potatoes are an important commodity in America today. U.S. farmers grew more than 47 million pounds last year. Can you imagine our society today without french fries?

Most Augusta-area gardeners try to have potatoes planted by Valentine's Day. Because our weather can be so unpredictable in February, it's hard to be precise when advising planting time.

Potatoes are considered a cool-season crop. They can be planted as soon as the ground has warmed slightly and dried enough. It's critical to let the soil dry, particularly if you have a clay soil. If you work the soil while it's still too wet, it becomes hard and compacted. That can lead to long-term frustration for the eager gardener.

Potatoes can adapt to most types of soil but must have good drainage to keep from rotting before they can be harvested.

It's best to take a soil test to determine pH and soil fertility. Potatoes grow best in acid soils with a pH of 5.0 to 5.5. A higher pH will increase the occurrence of scab disease. Lime will raise the pH, and elemental sulfur will lower it.

Potatoes are heavy feeders. They require about 3/4 to 1 pound of nitrogen per 100 feet of row. Set phosphorus and potassium rates based on the soil test. If you don't take a soil test, apply at least 1 to 2 pounds of phosphorus and potassium per 100 feet of row. Split fertilizer applications for more efficient use. Incorporate one-third before planting, one-third after emergence, and one-third three weeks after that.

The part of the plant we eat is called a tuber, a technical name that refers to an enlarged modified stem that grows underground. Potato tubers used to create a new planting are called seed potatoes.

You'll want to start with the best quality seed potatoes, so look for those labeled "certified disease-free" at garden shops and in mail-order catalogs. These seed potatoes have been treated with a fungicide to help prevent soil borne-diseases. Don't try to use store-bought potatoes. They haven't been treated.

There are two kinds of potatoes, whites and reds. The whites are best used for baking and frying, while the reds are best for boiling and potato salad. Both grow well in our area.

To start a new planting, cut the seed potato into pieces so each has at least one healthy looking bud (often called an eye). That bud will become the shoot of the new plant. As the stem develops, it also will produce new roots. The piece of tuber attached to the bud provides a source of carbohydrates to sustain the young plant until those roots and shoots develop.

Plant the pieces 2 to 3 inches deep. Space them about 12 inches apart in the row, and leave 24 to 36 inches between rows. As plants emerge and begin to grow, bed up the soil around the plants to encourage more potatoes. All new potatoes will form above the seed piece.

Potatoes should be ready for harvest about three to four months after planting, depending on variety and environmental conditions. The tubers can be dug as new potatoes before they reach full size and before the skins start to toughen.

New potatoes are tender and tasty, but they don't keep very long. Because the plant must be pulled up to harvest the tubers, yields are generally small.

If you want bigger yields of full-size tubers, it's best to leave them until they begin to die back on their own. As the plants begin to turn brown, gently lift the tubers with a digging fork and remove them from the plants. If the potatoes are going to be used right away, no further treatment is needed.

You can store potatoes three to five months if you keep them cool, but store only potatoes free of damage and disease. Hold them at 60 to 70 degrees for at least four days before storing them at 40 degrees. An unheated cellar or similar place is ideal for potato storage.

Potatoes in cool storage for a long time may develop high sugar content and taste sweet. These potatoes turn dark when cooked. To eliminate the sweet taste and dark color, raise the storage temperature to 70 degrees for one to four weeks before cooking.

Potatoes are rich in complex carbohydrates, fiber, vitamin C and magnesium and have no fat or cholesterol.

Sid Mullis is director of the University of Georgia Extension Service office for Richmond County. Call him at 821-2349, or send e-mail to smullis@uga.edu. The offices that serve Richmond and Columbia counties have a Web page at www.griffin.peachnet.edu/ga/columbia.