Sweet Potato

Sowing: Plant rooted vine cuttings called slips once the soil has warmed to about 65°F, since this is a tender warm-season crop. Set them in ridged rows roughly 12 to 14 inches apart within the row and 36 to 40 inches between rows, in full sun with at least 6 to 8 hours of light, in loamy or sandy soil that drains well and is rich in organic matter.

Watering: Keep moisture consistent, especially during the first 50 to 60 days after planting when the crop is most sensitive to drought. Water deeply in dry spells but avoid saturated soil, since excess water can cause the storage roots to split or rot.

Weeding and feeding: Remove weeds by hand until the vines fill in and begin shading them out on their own; mulching helps where weed pressure is high. The crop has a medium nutrient requirement best met with compost, and light sandy soils may need a nitrogen side-dressing, though heavy fertilizing can prevent good root formation.

Pests: Sweet potato weevils, flea beetles, thrips, voles, scurf, and nematodes can all trouble the crop, and populations of soil-borne pests build up when it is grown repeatedly in the same ground, so rotating plantings every couple of years is advised. Starting from certified disease-free slips helps avoid introducing weevils, since cuttings taken from the base of a vine carry weevils more often than cuttings from the tip.

Diseases: Leaf scab causes small brown, scabby lesions along the veins and petioles that distort and twist the leaves, while little leaf disease and virus symptoms also spread through infected planting material, so only healthy stock should be propagated. Fungal problems can affect the crop generally as well.

Disorders: Storage roots can split when soil moisture swings between dry and wet as the roots swell, and soil temperatures below 50°F cause chilling injury to roots left in the ground too long.

Harvest: Roots mature 85 to 120 days after planting; check their size from about day 80 to 85 onward, since they keep growing and can split if left too long, and dig them before frost strikes, cutting the vines away first to make lifting easier. Use a fork or spade to loosen the soil and gently lift the roots, handling them carefully without rubbing the skin or washing them before storage. If frost damages the vines, dig the roots at once since decay can spread from the dead vines into the roots; otherwise cut the vines back and cover the rows with loose soil for temporary protection.

Storage: Cure roots at a high temperature, roughly 85 to 95°F, and high humidity for about five to ten days, which converts starch to sugar and heals skin wounds. Afterward, store them in a cool, dry place around 55 to 60°F with good airflow rather than in a refrigerator, since roots continue to sweeten in storage but temperatures below 50°F cause off flavors or rot.

Culinary: The starchy storage roots are eaten baked, mashed, or fried, and are used in casseroles, soups, and pies, while the young leaves and shoots are also edible and can be eaten fresh in salads or sautéed as a leafy green.

Ornamental: Cultivars selected for colorful, deeply lobed or heart-shaped foliage in purple, chartreuse, or variegated tones are grown as groundcovers or trailing vines in containers, hanging baskets, and mixed beds, and their flowers attract bees and other pollinators.

Sweet potato is believed to have originated in the tropical regions of South America, Central America, and Mexico, where it was domesticated at least 5,000 years ago. It has since spread widely to become an important food crop across the world.