Growing Sweet Potatoes
By S.M.R. Saia
When you’re new to gardening, it’s easy to get discouraged by how much there is to learn. Worrying about what kind of soil you have, measuring your soil’s pH, and puzzling out N-P-K ratios can make gardening seem complicated and overwhelming. All of this is important, of course – but so is the willingness to just put something into the ground and hope for the best.
A novice gardener needs encouragement, and nothing is more encouraging than a bountiful crop. So if you’re looking for some almost-guaranteed gardening success, look no further than the sweet potato. Versatile in the kitchen and hardy in the garden, sweet potatoes are healthy, filling and delicious. They’re also one of the most forgiving of home garden crops. They will tolerate a wide range of soil conditions and grow in all 50 states. They aren’t particularly susceptible to pests, and once they get established they don’t require weeding. The vines spread out to form an attractive groundcover that produces purple blooms. Once harvested, they keep well for many months under the proper conditions.
My first sweet potatoes were Beauregard; pale, reddish skin with dark orange flesh. I had no experience and little information about growing sweet potatoes, but I ended up with a bumper crop that we enjoyed well through the winter.
Sweet potato basics
The sweet potato actually is not a potato at all. The potato is the underground part of the plant’s stem, which has thickened to provide food for the growing plant. The potato belongs to the Solanaceae (nightshade) family, whose other members include tomatoes, eggplants, peppers and tomatillos. The sweet potato, though, is a root. It is a member of the Convolvulaceae family and is closely related to the morning glory.
Sweet potatoes also are safer to eat than potatoes. Though some people are unable to eat potatoes because of an allergy-like sensitivity to the alkaloids they contain, sweet potatoes are free of these substances. Potatoes also will produce a poisonous compound called solanine if exposed to light while growing. The presence of solanine is detectable because as it develops the skin of the potato turns green. Sweet potatoes do not produce solanine, so if a sweet potato pushes up out of the ground and its tip turns green, there’s no need to throw it away.
The sweet potato does not have “eyes” or buds on its outer surface, and it is not started from “seed potatoes” the way regular potatoes are. When you plant sweet potatoes, what you’re actually planting are “slips,” shoots that grow from a mature sweet potato. Sweet potato slips can be ordered from a reputable seed company, or you can start your own at home.
Use a potato from your own crop or one grown organically. Submerge at least one-third of the potato into a jar of water and place in a sunny spot, such as a windowsill. When vines have reached about six inches, carefully twist them off and put the vines into a jar of water. Once roots have developed, the slips can be transplanted outdoors or potted for a beautiful indoor plant. You can also propagate new plants by taking cuttings. Snip off at least six inches from a mature vine and place the cutting in water. When roots appear, the vine can be transplanted to a container or moved out to your garden.
Send down those roots
Sweet potatoes like a slightly acidic soil with a soil pH between 5.0 and 6.5. A pH nearing 7.0 (neutral) may make the crop slightly more susceptible to some diseases; however, sweet potatoes are particularly tolerant of most soil conditions. Loose, well-drained soil allows formation of the largest tubers, but just about any soil will do, and the size and shape of the tuber does not affect the taste.
When planting slips, use the handle of a shovel to make holes for the delicate vines. Set them 10 to 18 inches apart in 3-foot rows. Pour a little water into each hole around the roots, then pat the soil firm around it.
Once the slips are in the ground, pretty much all you need to do is wait. No need to feed or fertilize. The vines will grow and fill in like a groundcover, and they will eventually produce lovely, delicate purple flowers that look a lot like a morning glory. They are a great crop for the suburban gardener looking for both beauty and utility in her landscaping.
Uncover buried treasure
Sweet potatoes mature in about 100 days. As the potatoes grow, you may see furrows in the ground where the vine meets the root, and the tips of the tubers may push up above the soil line. To get the tubers out of the ground, move the soil away from the base of each vine until some of the tubers are clearly exposed. Simply dig them out with your hands, going down far enough to lift them out one by one, or, if your soil is loose enough, use a pitchfork to lift them straight out of the ground by the vines. They can stay in the ground until the first frost, but if they are still in the ground when the first frost hits, they should be pulled up and brought in immediately.
The curing process makes the sweet potato sweeter by changing some starches to sugars. If you want to keep your crop around for awhile, curing is an important step. Do not wash potatoes. Sweet potatoes should be exposed to warm temperatures (80 to 85 degrees) and high humidity, which allows their skins to toughen. Place them somewhere warm and cover with a damp towel for 10 to 14 days, remoistening the towel as necessary. The skin is very thin, and it’s easy to nick or scrape it while pulling them out of the ground. This is not a problem, as any cuts or nicks will seal over during the curing process. If any tubers broke, the broken ends will “cork over,” developing a thick white covering.
At the end of the curing process, prepare your sweet potatoes for storage by wrapping them individually in newspaper or in brown paper lunch bags. Then pack them in open cardboard boxes, baskets or crates for storage.
Sweet potatoes need to be kept cool and dry, 50 to 60 degrees is ideal, though they will keep for several months at closer to 70 before beginning to sprout. Kept below 50, they may suffer injury from the cold.
We planted 27 sweet potato slips in April of last year, enjoyed our first sweet potato in late July, and ate our last one in early March this year.
Fixin’ to eat
Sweet potatoes are delicious either sweet or savory. They require little attention while cooking and only moments of preparation before serving. The following simple recipes showcase the natural richness of your crop. Always place sweet potatoes on a pan to bake, as they will ooze a syrupy kind of liquid as they cook.
Tangy Mashed Sweet Potatoes: This preparation will downplay the sweetness of the sweet potato somewhat. Bake 3 large sweet potatoes until soft enough to pierce easily with a fork; peel. Add 1?2 to 3?4 cup sour cream (to taste). Mash until smooth. Serve immediately, or save for later and reheat.
Candied Mashed Sweet Potatoes: To play up the sweetness without adding unnecessary sugars, prepare as above, substituting 1 cup unsweetened applesauce and 1?2 teaspoon mace for the sour cream. Mash until smooth. Place in a buttered casserole dish and bake at 350°F for 30 minutes to allow the flavors to blend.
Roasted Sweet Potatoes: Wash and cube sweet potatoes. Toss with olive oil and sprinkle with ground sea salt, cayenne pepper and crushed rosemary. Place in roasting pan or casserole dish. Roast at 400°F, stirring occasionally to make sure they don’t stick. Potatoes are ready when the edges are crispy and slightly brown. Serve immediately.
Sweet Potato Salad: Sweet potatoes are also quite delicious raw. For a quick summer salad, stir together 1 medium-sized raw sweet potato, peeled and grated; 1 large apple, grated; handful of raisins; handful of your favorite nuts (almonds, walnuts, pecans, etc.); and about 1?2 cup yogurt. Serve immediately.
Shannon Saia grows, stores and preserves sweet potatoes and an assortment of other vegetables on her suburban homestead in southern Maryland.
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