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Green Speak

Horticulture topics from gardens to lawns and then some.

How Sweet It Is...The Sweetpotato

There is something about fall that seems to bring me back to one of my favorite vegetables, the sweetpotato. Growing up, we only had sweetpotatoes at Thanksgiving so it wasn't until these past few years I discovered its true potential.

University of Illinois Extension Nutrition and Wellness Educator, Mekenzie Lewis, noted that the Center for Public Interest ranks the sweetpotato as one of the most nutritious vegetables and is an important source of vitamin A, C and B6, iron, potassium, and fiber. In addition the sweetpotato contains virtually no fat and is low in sodium. Mekenzie also mentioned the importance of fiber that the sweetpotato provides. Peter Greenwald, MD, director the Division of Cancer Prevention and Control of the National Cancer Institute believes that the fiber in sweetpotatoes may increase bulk in the colon, thereby "diluting" possible carcinogens that are found in food or which forms during digestion and lowers the risk of colon cancer.

Now that you have a glimpse of the many nutritional benefits of sweetpotatoes, let's move on to how to grow this super veggie. Sweetpotato or Ipomea batatas, is a tender vegetable native to Central and South America that requires a long frost-free growing season to mature. You may have noticed that sweetpotato is one word, not two- this is to distinguish it from true potatoes, which it is not. What is harvested from the sweetpotato is a tuberous root as opposed to a white potato which is a tuber.

Early spring is the time to start sweetpotatoes from plants called "slips". Make sure to order your slips from a reputable seed company, and try to go local if possible. You can make your own slips by taking a fully grown sweetpotato from a reputable source or the supermarket, and bury the bottom three-quarters in moist sand (keyword is moist not saturated). Soon the root will sprout the slips, which are green shoots with exposed roots. Carefully remove the slips and plant them in a cold frame, hot frame, high tunnel or in the garden once all danger of frost is clear.

Sweetpotatoes should be planted in a mound of loose loamy soil that reaches about eight-inches high. Make sure to give your sweetpotatoes plenty of room- as these vining plants prefer to spread and cover the soil. At minimum space them 12-inches apart and three-feet between rows. Some growers in our northern climate use black plastic mulch to warm the soil early in the season and get a head-start on root development.

Little care is required once the sweetpotato vines establish themselves. Ensure that you provide even watering, however, don't keep their rootzone constantly wet. Do not water during the last 3 to 4 weeks before harvest to protect the developing roots from splitting.

Wait until after the first frost to harvest your sweetpotatoes- this concentrates the sugars in the roots. Once frost hits you should harvest immediately to keep any decay from spreading aboveground to belowground. If we have a long stretch of cool weather (below 55°F but above freezing) it would be a wise decision to harvest, especially is the plants show cold weather damage. Cure your sweetpotato roots by allowing them to dry on the ground for two to three hours, place in a warm room or high tunnel for 10 to 14 days with a temperature of 85°F and 85% relative humidity. (This can be tough in the fall, but do the best you can) After curing, store in a cool (55°F+), dry location. Properly cured sweetpotatoes should keep the entire winter. Sweetpotatoes are members of the Convolvulaceae or morning glory family, and must be integrated in your crop rotation schedule.

My favorite way to prepare sweetpotatoes is to bake them in a 375°F oven for 45 minutes to an hour (depending on the size). Place your sweetpotato in a cast iron skillet to keep the drippings from making a mess in your oven. After baking I cut open the potato, sprinkle a pinch of kosher salt, and add just a drop of honey to bring out the sweet flavor.

Happy Harvesting!

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