Sweet potatoes are tropical, warm-season vegetables that typically have a long growing period. These cold-tender root vegetables need a minimum of four frost-free months to mature. Sweet potatoes grow from "slips," which are sprouted baby sweet potato plants. The sweet potato slips grow best if planted when nighttime temperatures stay warmer than 55 degrees F, and provide the best yields with night temperatures around 72 degrees F. Due to their long growing season and warm-weather requirements, sweet potatoes can be difficult or impossible to grow in cold regions.
Choose a planting site for the sweet potato slips in full, direct sunlight with well-draining soil. Loosen the top 12 to 15 inches of soil in the planting bed using a pitchfork or rototiller.
Spread a 2- to 4-inch-thick layer of organic compost on the planting bed and mix it into the soil to a depth of 6 to 12 inches. Mound up the soil to create rows of ridges that are 6 to 8 inches high and 12 inches wide, and space the ridges 3 to 4 feet apart.
Plant the sweet potato slips in spring after all danger of frost has passed and the soil has warmed up. Plant the sweet potato slips 12 to 18 inches apart in the ridges, burying the slips up to the bottom set of leaves.
Firm down the soil around the sweet potato slips with your hands and create a shallow ring in the soil around each plant. Water the sweet potato plants deeply and thoroughly each day for the first three to five days.
Water the sweet potato slips deeply to soak the soil to a depth of at least 6 inches once every week in the absence of rainfall or when conditions are hot and dry. Stop watering the sweet potato plants in late summer and early autumn.
Spread a 2- to 3-inch layer of organic mulch around the sweet potato plants about one month after planting the slips to control weeds. Or, hoe shallowly around the plants to get rid of weeds.