Mike’s Hot Spicy Food Recipes

April 18, 2008 - 11:50PM

Arizona Gardening: Nutritious sweet potatoes thrive in the heat

John Chapman, For the Tribune

Q: Can sweet potatoes be grown in the low desert?

A: The Center of Science in the Public Interest ranked sweet potatoes No. 1 in nutrition of all vegetables — they’re rich in vitamins A, C, E, beta carotene and other minerals. Beta carotene promotes healthy skin, hair and eyesight. Sweet potatoes have many times more beta carotene than carrots, the mineral for which carrots claim to be king.

Sweet potatoes are native to Central and South America, so they grow best in hot weather. Sweet potatoes won’t grow in cold soil, so there’s no point in planting them until the soil has warmed up to at least 70 degrees. April and May is the ideal time to plant them.

Sweet potatoes are grown from transplants or vine cuttings called slips, not from seeds. To start growing slips, buy a few sweet potatoes at the grocery store and place them on top of the water heater to hasten the sprouting and growing process.

After sprouts start showing, lay the sweet potatoes on their sides in no more than 2 inches of moist dirt. It’s all right if a few sprouts show through the soil. Covering the sprouts with clear plastic sheets will also hasten the growing.

Another way to grow slips is to stick toothpicks into the midsections of small, healthy sweet potatoes, then submerge them halfway in a jar of water and place in a sunny location. Slips are ready to pull in about six weeks, when the vines are 6 inches to 8 inches long. The sprouts (slips) are planted directly in the garden from the sprout bed.

(There are about 50 eyes on a medium sweet potato, and each one may produce a sprout so it is possible to grow several bushels of sweet potatoes with sprouts taken from just two or three sweet potatoes.)

Instead of allowing the vines to run all over your garden, you can grow the sweet potatoes in a tower of car tires. Put an old car tire over the newly planted slips. As the vines get longer, add more mulch or straw over the vines until the tire is full. As the vines grow continue to grow, add another car tire and then another up to four or five tires high.

Fertilize three to four weeks after planting, then every two to four weeks. Fertilizers high in nitrogen will result in a leafy, green plant at the expense of root development. Good fertilizers for sweet potatoes contain low levels of nitrogen — the first number in the fertilizer ratio — and high levels of phosphorus (the second number in the ratio). Look for blends like 6-24-24 or 8-24-24.

Irrigate only enough to keep adequate moisture. Overwatering will rot the sweet potatoes.

There is no perfect time for harvests. The most varieties can be harvested after 4 1/2 months in the field, or about 100 to 120 days after planting. Dig when leaves turn yellow. Do not water during the last 3 to 4 weeks before harvest to protect the developing roots.

Proper curing could be a problem in the cool fall season. Ideally, the sweet potatoes should be allowed to dry on the ground for 2 to 3 hours, then placed in a warm room for curing (85 degrees and 85 percent humidity, if possible) for 10 to 14 days and then stored in a cool (55 degrees) location.

CONTACT WRITER: john@johnchapman.com