This is the VOA Special English Agriculture Report.

True or false? Potatoes are root vegetables.

False. Potatoes are underground stems called tubers.

Most kinds of potatoes can be planted during cool weather. But John Masiunas of the University of Illinois Extension says it may be best to wait until after the last winter freeze.

The extension service says the best formation happens when the soil is between fifteen and twenty-one degrees Celsius. Tubers will not form if the soil temperature reaches twenty-seven degrees.

Potatoes are started from "seed pieces." These are either small whole potatoes or potatoes cut into pieces. Each piece should weigh about forty to sixty grams. The experts at the University of Illinois say pieces that weigh less than thirty grams may not produce as much.

Each piece must have at least one good "eye," the small dark spot where a sprout will grow. Soon after the pieces are cut, plant them twenty-five to thirty centimeters apart. Cover them in a furrow between two and one-half and seven and one-half centimeters deep. The rows should be spaced about sixty to ninety centimeters apart.

For potatoes, the best soil is fertile and well drained, not wet. To improve clay soils, mix in garden waste or other organic matter and turn the soil deeply in the fall. If possible, in the year before you plant potatoes, plant a cover crop to improve the soil and the potato production. The extension service suggests a crop such as clover, buckwheat or winter rye.

After the potato plants appear, organic mulch can be spread around to hold moisture, help suppress weed growth and cool the soil. John Masiunas says water management is extremely important. Potatoes do not grow well in very dry conditions.

Some gardeners plant potatoes under straw, or stems of dried grain. Instead of burying the seed pieces, place them at the surface. Then spread loose straw ten to fifteen centimeters deep over the seed pieces and between the planted rows. The potatoes should send up sprouts through the straw cover.

You can wait till the fall to harvest potatoes, or harvest them during the growing season as new potatoes. But whatever you do, make sure to handle potatoes carefully. They can bruise easily, and damaged potatoes can quickly go bad.

And that's the VOA Special English Agriculture Report, written by Jerilyn Watson. For more advice about growing potatoes and other vegetables, go to voaspecialenglish.com. I'm Bob Doughty.