White potatoes and sweet potatoes are grown almost in exactly the same way, except for the way they are planted. White potatoes are grown from eyes, which are little buds, and sweet potatoes are grown from slips. If you've ever forgotten a sweet potato somewhere, then found it growing with many white vines coming out of it, you've found potato slips. These beginnings of sweet potato plants can be used to grow dozens more potatoes for each one that you plant. Sprout your own slips, using an organic potato, or purchase them from garden centers or seed catalogs. You could be digging up buckets of sweet potatoes in the fall, just from one forgotten potato.
Dig down in the soil of your potato bed to a depth of about 1 foot. Remove any rocks or roots that may be in the soil. Dig in two shovelfuls of compost for each plant that you will grow.
Mound up the soil in the potato bed to create a small hill where each plant will grow. This will help the soil to warm and drain faster than the flat land around it.
Plant your sweet potato slips as soon after frost as possible. Sweet potatoes need a long growing season, so the sooner they are in the ground, the longer they have to grow. You can find your last frost date from Farmers' Almanac, at farmersalmanac.com, or your local extension office.
Set one slip in each hill. The hills should be about 18 inches apart and about 8 inches tall. You may also mound the soil up onto one long hill, planting slips all along the length, spacing them 12 to 18 inches apart. Each slip should be set in the ground with the leaves just appearing on top of the soil.
Lay black plastic over the soil, one sheet on either side of the slip row. This will help to keep the soil warm, while cutting down on the amount of weeds that grow in the potato patch.