1. Sweet potatoes are grown from slips, which are sprouts that are grown from stored sweet potatoes. You can buy slips from garden centers, nurseries, or local farmers.
2. You can also grow your own slips to plant in the spring. In November (this is when the best of the new harvest will be out), go to your supermarket and look for unblemished and uncracked medium sweet potatoes. One potato should yield about 12 plants.
3. Use a 1-1/2 gallon pot for every two potatoes. Remember to poke drainage holes in the bottom of the pot and fill it with 3 inches of mulch followed by garden or potting soil. Plant the potatoes in the pot at a 45° angle so that the sprouts will grow above the soil. When the slips are 6 to 12 inches tall, you can plant them outdoors as long as all danger of frost has passed.
4. After you have grown your own slips or bought them, till area of the garden you will be using to a depth of 8 to 10 inches. Create raised beds 6 to 8 inches tall and about 12 inches wide. Use fertile, well-drained soil.
5. Plant the slips 12 to 18 inches apart in the bed, after the last spring frost date. Plant the slips deep enough to cover the roots and about 1/2 inch of the stem. Water the slips with a starter solution that is high in phosphorous, then water generously for a few days to make sure that the plants root well.
6. You can start digging up the potatoes as soon as they are big enough for a meal. Often, this is three to four months from when you planted the slips. The leaves should have started to yellow, but you can leave them in the ground up until the fall frost.