The first year I grew sweet potatoes, I knew I’d hit the jackpot. Sweet potatoes are not only super easy to grow, but a small area is all you need to fill a year’s supply of this sweet delight. My own small, 4-feet-by-12-feet raised bed provides our family with 75 to 100 pounds of this versatile root crop — enough to make all the baked and roasted sweet potatoes, sweet potato pies, sweet potato soup, and any other creation that tempts our tastebuds for an entire year. And best of all, you only need two or three potatoes to get a perennial supply started on your homestead.
Sweet potatoes or yams?
Sadly, the sweet potato is a victim of mistaken identity. Dating as far back as colonial times, orange fleshed varieties have been routinely labeled as yams, yet they’re not yams at all. Sweet potatoes (Ipomoea batatas) belong to the the morning glory family (Convolvulaceae), while true yams (Dioscorea L) reside in the aptly named yam family (Dioscoreaceae). In the United States, only sweet potatoes are grown commercially with yams being relegated to specialty growers and markets. So despite names such as "candied yams" or "fresh, local yams," most of us are only familiar with the sweet potato.
Children often find the water jar method an exciting introduction to gardening since they can easily see daily root growth and sprout production.
Start with slips.
Sweet potatoes are not grown from seed. Instead, small shoots called slips are sprouted from a sweet potato from the previous year’s harvest. Once slips reach the desired length, they are "slipped" off the root and then planted in the ground. You can either purchase ready-to-plant slips from local nurseries, catalogs, or other growers, or you can sprout slips yourself from a sweet potato purchased at the supermarket. If going this route, select only organic varieties as conventionally grown sweet potatoes are often treated to prevent sprouting.
Starting your own slips is simple, though it does require a bit of planning because the process takes between four to six weeks. Most sweet potatoes require 90 to 110 days to reach harvest size, so slips should be ready to plant as soon as soil temps reach 60 degrees Fahrenheit and all danger of frost has passed. In my neck of the woods, planting dates generally range from mid-April to the end of May, making the best times to start the slip growing process sometime between the end of February and April. However, if your summer begins sooner or later than ours, you’ll need to adjust your slip starting date accordingly.
Several methods exist to sprout slips, but the two most common are the water jar and sand box methods. The water jar method is likely the most familiar as many of us unwittingly grew slips in our elementary science classes. Simply skewer any disease free sweet potato midway down with three or four toothpicks around the root’s circumference. Balance the potato in a water filled jar and set in a window or under grow lights. Make sure to change the water every few days to avoid stagnant, stinky jars.
Fill a container with sand, potting soil, chopped leaves, or sawdust. Place roots close together, but not touching, into medium. Cover with plastic wrap and place on a heat mat to speed the process. Uncover once sprouts appear.
Just as easy, the sandbox method offers the winter weary gardener an opportunity to dig in the dirt. Fill a small tote, box, or flower pot with moist sand or potting soil. Nestle the sweet potato on its side in the planting medium, leaving up to half of the top exposed. Another option is to cover the entire root with 1 to 2 inches of sand/soil. Be sure to keep the soil moist at all times so the root doesn't dry out.
Both methods will sprout slips within a week or two with a single potato producing up to 20 slips over three or four weeks. Once slips reach 6 to 9 inches, cut them off at the root. The slips are now ready to plant, or place them in jar of water to allow roots to develop. However, it’s not necessary to have roots prior to planting.
While sweet potatoes are not fussy, they do require consistently warm (60-65 degrees) soil at planting time. Once soil temps are stable, plant slips 3 to 4 incehs deep, 10 to 18 inches apart in well-drained soil (sandy loam is best for uniform root development) with a pH of 5.7-6.7. If possible, use raised beds to provide good drainage if your area experiences heavy spring rains. In drier weather, provide 1 inch of water weekly as needed.
Harvest and cure.
Dig roots with a spade fork before soil cools to 50 degrees and before the first hard frost hits. Allow soil to dry on roots. Cure in a shaded, well-ventilated area between 85-90 degrees for seven to 10 days. Then store at 55-60 degrees in a dark location such as a closet or pantry in baskets or burlap sacks. Allow three to four weeks for the full flavor to develop before enjoying.
Easily adaptable to a variety of growing conditions, every garden has a place for a few sweet potatoes. If you start your slips now, you’ll be enjoying homegrown candied yams by Thanksgiving!