This spring, keep sweet potatoes in mind as you plant your container garden. Leafy and ornamental, those purple, chartreuse, or bronze colored sweet potato vines bring out the best in their flowery companions.
Ornamental varieties are a natural choice for big containers and hanging baskets, and they have won the hearts of gardeners everywhere. You’ve heard the “recipe” for container combos, right? Choose a filler (that could be petunias filling the middle) a spiller (that could be the sweet potato vines dangling down, the farther the better), and a thriller (maybe a large-leaved coleus in wild colors, standing tall). By the way, sweet potatoes (Ipomoea batatas) are not potatoes but are relatives of morning glories, with similar flowers.
Sweet potato vines are an attractive spiller. They grow fast and like a lot of sun, food, and water. Naturally, people are curious about the tubers they find in their pots at the end of the season. Sometimes the tubers grow so large that they stick up from the container or even split the side of their pot. Better choose the slower growers for hanging pots.
Like field varieties, ornamental sweet potatoes go dormant by forming starchy tubers. The tubers are great for saving special varieties for next year. Dry them off and store them in a dry, cool cellar inside mesh or paper bags.
The leaves and tubers of ornamental types are edible, but that does not mean they taste good or are sweet. The flavor varies and some types are bitter. Newer varieties have been bred to grow slowly and not make large tubers. People don’t know that you can steam the leaves or use them for salad. I tasted the leaves of some ornamental types and found them bland in flavor but good for a dash of salad color.
If you are interested in sweet potatoes for a landscape combining food and beauty, grow the edible types. With big green hearts for leaves, they are almost as pretty as the ornamental ones, and if you don’t get many tubers because of a short growing season, at least you can eat the plentiful leaves in stir-fry or salad. You can buy plants by mail order from certain suppliers, or you can start your own.
I’ve tried the well-known method where a piece of the edible sweet potato itself is propped in a glass of water to grow roots and shoots, but it often goes soft and rots instead. My way for growing rooted cuttings, known as slips, is to buy a big orange-fleshed sweet potato such as Vardaman. Try to get an unblemished one from an organic food source. It may have been treated with a chemical to retard sprouting, but that won’t stop it forever. Sometimes this type is called a yam but isn’t really a true yam.
Wrap it lightly in plastic with a few little air holes—this keeps it from drying out but is not too moist. Put it in a dark cupboard where it will not be forgotten. After a few weeks, unwrap it and harvest the fat sprouts that have started to grow.
Get them when they are about three inches long. Pull the sprouts off all the way down to where they connect to the potato and then set them into jars of water on a windowsill (bottom half in, upper half out) or into potting soil in pots (keep it moist). When the ones in water grow roots, pot them up or plant them outside (after all danger of frost). The leaves may be purple at first. By the way, after you pull off all the sprouts for slips you can still roast and eat the potato if it is firm. Or put it back in its wrapper to grow more sprouts.
People love the chartreuse-leaved sweet potatoes because they look great with red, yellow, orangewarm-colored flowers.
You can give the ornamental ones similar treatment or take cuttings to keep them going. There are lots of types that are just too good to lose. The most popular is a chartreuse-leaved one called Margarita” (also known as Marguerite), a fast grower with big heart-shaped leaves—you see it everywhere.
There are purple, black, bronze, and light green forms, plus one appropriately called Tricolor,” which is pink, green, and white. There is diversity in the leaf shape, texture, vigor, and vine length, but you may have to search for special varieties. More names to look for are Blackie”; the Sweet Caroline” series in multiple colors including the reddish Bewitched”; and Illusion Emerald Lace,” which is deeply toothed.
Kristina Wade, Annuals Specialist for Terrain at Styers in Glen Mills, Pa., uses ornamental sweet potatoes in many designs, but likes them best planted in tall urns several feet high. This allows the vines to trail down attractively.
She likes to combine a black-leaved sweet potato with a black urn, and a bright green leaf with a gray urn. She says people love the chartreuse-leaved sweet potatoes because they look great with red, yellow, orange—warm-colored flowers. The dark purple, bronze-leaved, or black-leaved sweet potatoes look best with cool blue, pink, and purple flowers. Wade combined a bronze-leaved plant with a hot pink geranium for me and it looked great. She knew it would, she tests new combinations all the time.
As for care, she says that the more sun, the better. The ornamentals are heat tolerant but not extremely so compared to field types. Kristina rates them a seven out of ten for that.