Sweet potatoes (Ipomoea batatas) are a fast-growing, ground-hugging vine. Not only does the vine's dense foliage make for an attractive groundcover, but it also grows sweet, starchy underground tubers. The plants produce ready-to-harvest potatoes within three months of planting and can be directly sowed into the ground as soon as the outdoor soil temperature gets above 70 degrees F.
Break up and loosen the soil with a spade or mechanical tiller, as sweet potatoes are an underground crop that need loose soil for optimal growth. Dig at least 7 inches deep.
Fertilize the soil with a general 10-10-10 or 5-10-10 granular vegetable fertilizer. For the best results, use 1 1/2 lbs. of fertilizer for every 50 square feet of gardening soil.
Plant the seed sweet potatoes. Bury the seed potato 2 to 3 inches below the soil surface. If you're growing more than one sweet potato vine, separate them by 9 to 12 inches and space the rows apart by 3 feet.
Water the planting site once a day, using enough water to moisten the soil to a depth of 3 to 5 inches. The sweet potatoes will typically sprout within 10 to 14 days. Once sprouted, water the sweet potatoes once a week. Use enough irrigation to moisten the soil to a depth of 6 to 8 inches.
Hoe the area to remove any weeds that may sprout. (This won't be a problem once the vines cover the soil surface.) Don't hoe deeper than 1 inch, as this may disturb the underground sweet potato tubers.
Stop watering three weeks before the harvesting date. Harvest typically occurs 100 to 110 days after planting for most sweet potato varieties.
Harvest the sweet potatoes. Use a spade or, for reduced breakage, a garden fork to gently dig the plant and its tubers out of the ground. Brush the tubers clean, trim off the connected vines and foliage and cure the potatoes by storing them at 80 degrees F for two weeks before using them.