The growing of sweet potatoes dates back to 750 B.C. Sweet potatoes belong to the Convolvulaceae or morning glory plant family, and should not be confused with regular potatoes and yams, both of which are entirely different from sweet potatoes.
There are about 400 varieties of sweet potato, differentiated by their skin and flesh color, which ranges from cream, yellow and orange to pink or purple. Oxidation turns them dark in spots after peeling, so it’s best to bake or steam immediately, or place them in water until you do. Using a ceramic knife may also slow down browning.
Baked sweet potatoes are a tasty and healthy alternative to regular potatoes, especially served with butter, salt and pepper, and sweet potatoes are very easy to grow in most locations. Popular varieties among gardeners include:1
- Beauregard — A popular commercial variety of sweet potato with dark orange flesh and pale-red skin; matures in about 100 days
- Bush Porto Rico — A good choice for smaller gardens as it has more compact vines and produce robust yields. Matures in 110 days
- Centennial — Disease resistant with slightly faster maturation rate; may be harvested as early as 90 days
- Georgia Jet — Another good choice if you have a shorter season; matures in 90 days
- Patriot — Pest resistant; recommended for organic gardens. Matures in 100 days
- Ruddy — Resistant to many insects, diseases and nematodes; matures in 100 days
Sweet Potato Propagation Methods: Slips and Vine Cuttings
Sweet potatoes can be easily propagated from “slips,” the small vines that grow out of a piece of the tuber. You can easily propagate your own slips as follows:
1. Slice an organic sweet potato in half lengthwise (conventional sweet potatoes don’t work well as most are treated to prevent sprouting)
2. Fill a pot about halfway with moist potting soil with plenty of organic matter such as worm castings, bat guano, pearlite, peat moss or coconut corn, organic compost (nonorganic chicken or cow manure tends to come from animals raised in concentrated animal feeding operations and have been fed genetically engineered grains), or organic ready-made potting mix. For strong growth, you’ll want slightly acidic soil with a pH between 5.0 and 6.5.
3. Place the sweet potato halves in the pot and cover with a light layer of soil. Lightly water to moisten the soil
4. Make sure the slips are placed in a warm area. Roots will develop in a few days
5. Once the plant has grown to a height of 4 to 8 inches, which will take about six weeks, the slips (the foliage tops) can be gently separated from the tuber they grew out of and planted in your garden (see video above). If some of the slips still do not have roots at this point, leave them in a glass of water until roots have formed, at which point they’re ready to be planted
An alternative propagation method detailed by The Spruce is to start the slips from a vine cutting instead:2
“If you have a short winter, you can begin new slips from vine cuttings. Snip off about 6 inches from the tips of the vines, before frost. Place these cuttings in water. Once they develop roots, plant in soil and keep them in a sunny location until it’s time to plant them outdoors.”
Sweet Potato Planting, Harvesting and Storage Guidelines
Your slips (sweet potato plants) can be planted in your garden as soon as there’s no danger of frost and the ground is warm enough to be worked. Here are some general guidelines:
- Prepare the soil by working in plenty of organic matter (see suggestions above)
- Plant in full sun to partial shade
- Space the plants 12 to 18 inches apart, ideally in 8-inch raised rows. Using raised rows will warm the soil faster and improve drainage. Leave 3 to 4 feet between each row. Since the tubers average 4 to 6 inches in length, and the vines can grow up to 20 feet in length, each plant needs plenty of space
- Water regularly during growing season, but avoid using fertilizer, as this will not improve the size of the tubers (it typically just increases foliage on the vine)
- The sweet potatoes will be ready to harvest in three to four months, depending on the variety. During the last month before harvest, minimize watering to prevent the tubers from splitting
You can tell the tubers are ready to harvest once the foliage starts to turn yellow. If you leave them too long past this point, the tubers will begin to rot, so be sure to dig them out once the vines begin to die back. The tubers tend to be close to the surface, so use caution when digging.
While larger tubers may seem appealing, small- to medium-sized ones tend to be sweeter and have a creamier texture. Larger sweet potatoes tend to be starchier. If the sweet potato feels soft or in any way squishy, it’s started to rot and is best discarded.
According to the North Carolina Sweet Potato Commission, sweet potatoes should be stored in a cool, dry, well-ventilated place, such as a root cellar or kitchen pantry — not your fridge, as cold temperatures will turn the center hard and create an unpleasant taste.3 Stored correctly, your sweet potatoes will stay fresh for up to two weeks. Once they start to shrivel and go soft, they’re past their prime.
Health Benefits of Sweet Potatoes
Yellow and orange sweet potatoes are rich in beta-carotene, a carotenoid responsible for the tuber’s yellow-orange appearance. As an antioxidant, beta-carotene can help ward off free radicals that damage cells through oxidation, which can speed up aging and make you vulnerable to chronic diseases.
Beta-carotene also helps support your immune system, and helps lower your risk of heart disease and cancer.4 By converting to retinol (vitamin A), beta-carotene also supports healthy vision.5
Purple sweet potatoes contain anthocyanins, another natural pigment with powerful antioxidant, antiobesity,6 anti-inflammatory and anticarcinogenic7 activities. Because they also prevent platelets from sticking together, they help prevent blood clots, which may in turn help fight heart disease.8
Other polyphenols in purple sweet potatoes include cyanidins and peonidins, which also have strong counter effects on cancer cell growth.9 These polyphenols may also lower the dangers posed by heavy metals and oxygen radicals, including mercury, cadmium and arsenic.10
Sweet potatoes also contain two important antioxidant enzymes: copper/zinc superoxide dismutase and catalase, and are great sources of vitamins C and B6, copper, dietary fiber, niacin, potassium and iron.11
Cooking Sweet Potatoes Correctly Increases Nutrient Bioavailability
Steaming or baking your sweet potatoes will improve the bioavailability of beta-carotene, making the antioxidant more accessible to your body.12 Boiling tends to destroy many of its beneficial compounds. To avoid browning, place the sweet potatoes in water immediately after peeling unless you’re going to steam or bake them right away.
Since beta-carotene is fat-soluble, I recommend eating your sweet potatoes with a small amount of fat, such as butter. Being low on the glycemic index, sweet potatoes are particularly well-suited for diabetics, and are a great choice for infants starting on solid foods. Simply puree the sweet potatoes, and serve with mashed avocado or cooked peas and carrots.
Try This Sweet Potato Recipe
There’s no shortage of recipes for sweet potatoes. This simple and tasty oven sweet potato fries recipe from Instructables.com13 can get you started.
Perfect Oven Sweet Potato Fries
- One sweet potato (serves two people)
- Sea salt, coarse
- Black pepper, ground
- Olive oil (coconut oil can serve as a better option)
- Heat the oven to 450 degrees Fahrenheit
- Cut the sweet potato into large chunks about one-half to three-fourths inches thick. If leaving the skin on, make sure to scrub it thoroughly before cutting
- Place the sweet potato fries into a baking sheet and sprinkle a pinch of sea salt and ground black pepper on top. Next, drizzle the fries with about one-eighth cup of oil
- Place in the oven for 15 minutes. Take them out, flip the slices and return to oven for 10 minutes