Though they are similar to yams and standard potatoes in both appearance and use, sweet potatoes are actually a member of the morning glory family. This unique orange (and sometimes white, yellow, or purple) tuberous root therefore has distinct flavor properties and growing requirements.
Sweet potatoes are not grown from seed but from slips, which are shoots sprouting from the sweet potato itself. These slips are generally available for purchase at your local nursery or online gardening retailer. Once you’ve got your slips and gardening supplies handy, read on to learn how to grow sweet potatoes in your home garden!
When to Plant Sweet Potato Slips
Before you jump into planting your slips, you need to consider the timing. As a tropical plant, sweet potatoes typically require four months of warm climate and soil. If your climate does not have at least four months of air temperatures between 65°F and 95°F, consider using a short-season varietal. Generally, three to four weeks after the last frost in the spring, or when the soil reaches 65°F, is a good time to start.
Where to Plant Sweet Potatoes
Once you have an idea of when to plant your sweet potato slips, you can begin to prepare the planting site. Choose a space in your garden with full sun or some partial afternoon shade. Unfortunately, if your soil is clay or rocky, the potatoes could turn out stunted. To counteract this, you may need to purchase some soil that is loamy, sandy, and acidic. Just beware of soil or compost products containing too much nitrogen, which promote the growth of leafy greens, as opposed to plump roots. A 5-10-10 fertilizer is ideal. With your planting location all set, go ahead and build your rows. The raised rows should be 8 inches high and spaced about 3 to 4 feet apart.
Planting Sweet Potatoes
With your growing site prepared, you’re ready to start planting! Plant your sweet potato slips into mounds about 3 feet apart. To give you an idea of how much to plant, bear in mind that one 10-foot row will typically produce about 10 pounds of potatoes. Make sure to cover the roots and stem with soil and compost but not the leaves. Don’t forget to use row covers after planting if you live in a colder, northern climate or can expect more late-night frosts to come. Last but not least, give them plenty of high-phosphorus liquid fertilizer and water them rigorously for the following week to help them settle.
Growing Sweet Potato Plants
Once they are settled into their growing location, sweet potatoes won’t require as much water as that first week. Still, give them at least one inch of water per week, especially during the hottest days of the summer. Plenty of water during this peak heat phase will improve the plants’ output. Once they are about four weeks from maturity, back off on the watering. Too much during the last month of growth can cause the tuberous root to split, creating issues for storage later on.
Continue using liquid fertilizer during the growing period, but remember that many fertilizers encourage leaf growth rather than root growth. Steer away from nitrogen-rich fertilizers and opt for high-phosphorous ones instead. Feel free to add more 5-10-10 fertilizer, sandy soil, and compost.
About two weeks after planting, start weeding your rows regularly, but be careful not to disturb the tender sweet potato roots. In addition, don’t prune your sweet potato plants, as the leaves are important for root growth. After about 90 to 120 days, your sweet potatoes will be mature and ready for harvest!
Harvesting Sweet Potatoes
Around that 3-4 month mark – or at the latest, before the first frost of autumn – you can start harvesting your sweet potatoes. You can tell when they are ready for harvest when the tubers are large enough to eat or when the leaves and vines begin yellowing. Check on the sweet potato tubers by gently loosening and removing soil around the base of the stem.
Feel free to cut away vines that are in your way. However, keep most of the leaves attached so the plant can continue growing throughout the summer and fall seasons. Just be careful to snip the roots or the crown only when you are sure the plant is ready for harvest.
Gently pull the plant up by the crown (where the stem meets the root), and use your hands to dig out the root. You may find as many as five or more sweet potatoes in one plant. Handle the potatoes with care, as they are prone to bruising and scratching; tears in the potato skin can result in early spoilage. Brush or shake off the dirt, but wait to wash the potatoes until you are ready to use them.
Storing Sweet Potatoes
Now that you’ve got your basket full of sweet potatoes, you’ll have to learn how to cure them so that they’ll keep properly. First, let them sit in the sun for a few hours to allow any excess moisture to evaporate. After this, lay them out with space between each for 10 to 15 days in a place with an air temperature of at least 80°F and 90% humidity. Once they are cured via this method, you can store them for up to 6 months in your basement or another shady area with a humidity level of 60%.
Sweet potatoes are a popular Southern root crop and have proven useful in the kitchen in many ways. They can create a delicious side dish, a comforting complement to a main course, or even a marshmallow-topped dessert. You can boil them into a soup, bake them into bread, use them in casseroles, or cut them into fries. Sweet potatoes are also highly nutritious, with plenty of minerals, vitamins, and antioxidants to go ’round.
As for their role in the garden, they offer attractive foliage and plenty of ground cover as an added benefit. While the growing process may seem intimidating initially, anyone can do it successfully by following a few simple steps. With the proper care and attention, your sweet potato plants will make an excellent addition both to your home garden and your home-cooked meals!