Sweet potatoes are a very-tender vegetable that grows best in warm weather. They spread on the ground as a thick groundcover, so look for bush varieties if growing in a small space or square foot garden.
Sweet potatoes are planted from “slips”–these are small plants created by cutting a piece of sweet potato vine, or sprouted from a mature sweet potato. Plant slips in the garden 2 weeks after the spring frost date.
You can make your own slips, or purchase them. To plant from a vine, cut one foot from a sweet potato vine. Remove all the leaves except the top cluster, and plant the vine in the ground so only the top leaves are above the surface.
To grow sprouts, 4 weeks before the spring frost date, place a sweet potato in a jar of water suspended by toothpicks or skewers. Half of the potato should be submerged under the water. Change the water every several days. Transplant the sprouts 2 weeks after the spring frost date by separating them from the potato, removing all but the top several leaves, and planting the stem in the ground.
Water daily for the first week, and every other day for the second week.
Sweet potatoes require lots of sun and night time temperatures above 55°F (13°C) to set fruit, so even in areas without frost it is unlikely you can grow them during the winter.
Soil and Fertilizer
Sweet potatoes grow best in loose, well draining soil; prepare the soil at least 8” deep and amend with lots of compost. You will need at least 10-12” (25-30cm) of soil if growing in a raised bed.
Fertilizer: Apply 16-16-8 at planting
Let the sweet potatoes grow as long as possible. After the first light frost, carefully harvest the potatoes to prevent bruising. Let them dry outside for several hours, then cure them for 1-2 weeks at 80-85°F (27-30°C). Store in a cool, dry location.