Sweet potato is packed with beta carotene and a delicious, more nutritious alternative to potatoes. While not related to yams, it's often labeled as such in grocery stores.
type of perennial: vegetable
Sweet potato comes in orange-, purple-, and white-fleshed varieties. For orange varieties, check out Nancy Hall, which grows best in warm regions. Georgia Jet does well in cool regions. And Beauregard grows well just about anywhere. For purple sweet potatoes, try Bonita, O Henry, and Sumor. For white, you'll want Violetta or All Purple.
WHERE SWEET POTATO THRIVES
Sweet potatoes can be grown with success in cooler regions of the United States, but do best best in the southern part of the country, with its long, hot summers.
Optimal shade & sun
Sweet potatoes are tropical plants that need at least eight hours of full sun per day.
Adaptability to climate extremes
Sweet potatoes thrive in the hot, humid extremes of the Southern United States. They fare better in wet climate extremes than in dry ones, and in hot extremes rather than cold ones. The sweet tubers are extremely sensitive to salty soils, which will inhibit the growth of its prized roots.
Because they are best grown in moist, humid regions, sweet potatoes are not particularly drought tolerant.
PREP YOUR SOIL
optimal type of soil
Sweet potatoes prefer a mildly acidic soil in a well-drained, warm site. Sweet potatoes grown in alkaline soils are more susceptible to disease. Good drainage helps prevent the tubers from rot. Sweet potatoes will grow in compact clay soils but they'll be rough and irregularly shaped. Sweet potatoes grown in a light loam soil will be uniform in size.
When planting indoors:
Sweet potatoes are not grown from seeds like other perennials. They're grown from slips or plant shoots that are sprouted from a mature sweet potato. You can get slips from any of your favorite seed catalogues. Don't fret if your slips show up wilted or dry, a common consequence of shipping stress. You can rehydrate your slips by wrapping their roots in a wet paper towel. It's also possible to sprout your own sweet potatoes from store bought tubers. Clean your tubers then cut them in half. Suspend each half, face down, over a jar of water. Use toothpicks to hold most of it above the water. Keep the jar in a warm place and you'll soon see shoots grow. Once the shoots are five inches long, gently snap them from the sweet potato. Place each shoot in a shallow bowl of water so the stem is submerged and the leaf end hangs out of the bowl. Within a few days you'll start seeing root hairs growing from the stem. The slips will be ready to plant once the roots get to be about an inch long. Keep the rooting slips healthy by changing the water daily. Discard any slips that are not producing roots, or begin to wilt.
When planting in the garden:
In a warm, sunny site, plant slips roots down into the soil. Individual plants should be spaced 12 to 18 inches apart and rows should be three to four feet apart. You can also plant whole tubers in the ground from store bought sweet potatoes. Simply dig a trench and cover the tubers completely with soil. The deeper you plant the tuber, the more sweet potatoes you'll be able to harvest.
Sweet potatoes grow quickly, within about two weeks of planting, and its foliage can quickly take over the planted area. In cooler areas getting the soil warm enough to plant can be a challenge. Try using heavy mulch or black plastic to keep the soil warm. Watch out for weeds. More importantly, try to avoid planting sweet potatoes in grassy and recently-grassy areas of your garden, because grass-loving pests may come back to feast on them.
Water your sweet potatoes thoroughly and frequently, particularly in the first month of growth. After the vines start to trail through the garden you can water plants an inch a week. Be careful not to overwater your plants or you can cause the tubers to rot underground. Make sure the soil has time to fully dry between each watering.
Before your plants get too big, mulch with a layer of straw or wood chips to keep your soil moist. This is particularly important in warm climates.
The candied flesh of sweet potatoes is admired by many and pests like it, too. Various caterpillars, such as armyworms and hornworm, love to gnaw on sweet potato foliage. They can be controlled by spraying Bt, a natural soil bacteria, or an insecticidal soap on the leaves. The most destructive pests live beneath the soil and, for that reason, are very hard to control. The larval form of many beetles feed on the tubers, creating holes and tunnels throughout the potato, which can lead to rot. Large pests, such as rabbits, rats, and even deer, can't resist sweet potatoes and will dig them up.
Fungal and bacterial rots can damage the roots and among the most problematic is fusarium wilt. It stunts and wilts the vines and creates hard, dark spots on the potato. Infected tubers should never be replanted or used to produce slips because the disease can be passed along. Prevention is the best defense so plant your tubers in well drained soil.