If you’re looking for a power food, it’s really hard to beat a sweet potato. These delicious, versatile tubers come in an array of colors, shapes, and sizes, and they’re also incredibly nutritious. Yet, many gardeners seem a little nervous about giving them a go, even though they’re easy and fun to grow. Don’t let fear be your guide: let us take your hand and introduce you to the wide world of sweet potatoes.
First, a moment of botanic pedantry. Sweet potatoes, also known as Ipomoea batatas, are starchy tubers native to Central and Southern America, with a cultivation history dating back thousands of years. The name is a red herring — they’re not actually related to potatoes, which are in the nightshade family. (Sweet potatoes are related to morning glories, and have lovely flowers to prove it.)
You may sometimes hear some sweet potato cultivars (it’s estimated that there are at least 7,000 in total) referred to as “yams.” That’s incorrect: a yam is a tuber native to Africa, with a very different genetic heritage and flavor profile. “Yams” are usually Covington Sweet Potatoes, a very popular commercial cultivar. You may also be familiar with Japanese Sweet Potatoes, which have dark purple skin and white flesh, as well as O’Henry Sweet Potatoes, with light yellow skin and flesh — when you think of a “sweet potato,” you may well have an O’Henry in mind.
Depending on the cultivar, sweet potatoes can contain lots of vitamins A and C, along with fiber and antioxidants. They’re also high in potassium. In comparison with potatoes, they tend to have a lot more going on nutritionally, along with that rich, sweet flavor that’s so distinctive. No wonder people love roasting them, baking them in pies, mashing them, including them in curries, and frying them, especially at Thanksgiving.
So, how do you grow them? You’re going to start with stem cuttings, called “slips,” which grow on the ends of tubers that have weathered the winter. You have the option of ordering slips from a nursery or plant supply, or producing your own. To make your own, grab some parent tubers, soak them overnight in warm water, and then plant them sideways, covering them partway in potting soil so part of the tuber is exposed. The potting soil should have a high percentage of sand to help them drain well instead of rotting.
As the potatoes start to produce shoots, bring them outdoors after the last chance of frost has passed. Let the developing shoots become slips of about four inches in length and then remove them from the tuber so you can plant them individually. They’ll prefer rich, well-drained soil in full sun for the best growing conditions, and they love it if you add a little fully-processed compost to the soil before you plant them.
Depending on which variety you grow, you’ll need between 12 and 18 inches of leeway between plants for them to grow. Some cultivars start maturing as early as 90 days after planting, while others take longer. Start regularly checking on them so you can harvest at optimal size. Gently dig up the whole plant, and get ready to cure your sweet potatoes: this will allow you to store them over the winter.
For curing, the sweet potatoes should be laid out in a humid environment where temperatures hold stable at around 80 degrees for at least a week, and preferably ten days. This allows the tubers to develop a tough “second skin” that will protect them in storage. Keep the space ventilated throughout curing. At the end of the process, look over your sweet potatoes and select the best specimens for storage. Their flavor actually improves the longer they’re held in storage, and they can last for up to 10 months!
In the long term, make sure to rotate your sweet potatoes, rather than planting them in the same bed year after year. This can reduce the risk of garden pests, and will limit the number of times you’ll be calling an exterminator to help you deal with insects and other organisms. Be aware that deer, rats, and other mammals are very fond of sweet potatoes (and no wonder, because they are delicious), so they should be grown in a secure area of the garden where larger pests can’t get to them — consider adding some tough Atlanta fencing to your garden to keep visitors at bay.