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The Homeowners Column
Sweet potatoes move from the plate to the estate
State Master Gardener Coordinator
The beauty of sweet potato leaves was once the sole delight of vegetable growers. However over the last decade a bounty of ornamental sweet potato cultivars have cropped up for sale next to the petunias and geraniums. 'Blackie' with its dark burgundy leaves and 'Margarita' with its bright chartreuse leaves were the first cultivars to be appreciated for their foliage and not their tasty roots.
Ornamental sweet potatoes are the same species as the edible sweet potato (Ipomoea batatas) and a member of the morning glory family (Convolvulaceae). During the long daylight of summer sweet potatoes seldom produce the trumpet shaped flowers characteristic of morning glories.
Just like the edible sweet potatoes ornamental cultivars are warm-loving, sun loving plants. They do not tolerate frost and are best planted when all chance of frost has passed. They prefer a moist, not soggy soil, but they will tolerate short periods of drought. Ornamental sweet potatoes do very well in containers in full sun to light shade and as groundcovers where their long vines can meander.
A dizzying array of ornamental sweet potato cultivars is now available. Leaf colors include tri-color of white, green and pink, chartreuse, coppery bronze and burgundy black. Leaf shapes range from large heart-shaped to finely lobed resembling Japanese maple leaves. Sweet potatoes must be a plant breeder's "dream come true". Chartreuse colored leaves are the most popular cultivars among gardeners since they easily light up a landscape. Dark leaved cultivars are excellent, but selection of their plant companions requires a little more forethought. They are best combined with light colored leaved plants otherwise they create a boring black hole.
Although sweet potatoes are vines, they are weak climbers so if you want them to go vertical you will have to weave and train the vines yourself. They are best grown as rambling groundcovers or as spillers cascading over the side of a container or hanging basket or draping over a retaining wall. Some of the cultivars are quite vigorous growers so give them plenty of room. I've watched them engulf neighboring plants. For example the vines of the burgundy-black leafed cultivars, 'Blackie' and 'Black Heart', can trail to six feet long. The vines can be cut back if they grow too long, but these cultivars are best used in very large containers and landscape spaces.
The newer cultivars (available in a variety of colors and leaf shapes) in the 'Sweet Caroline' and Illusion® series have smaller root systems, do not form large tuberous roots, are less vigorous and easier to use in smaller containers typical of home landscapes. They don't demonstrate the ravenous hunger to eat neighboring plants of the older cultivars. 'Sweet Caroline Bewitched' reportedly has a more compact upright growth habit than the other 'Sweet Carolines'. 'Illusion® 'Emerald Lace' and 'Midnight Lace' have more delicate deeply lobed leaves and much finer texture with vines reaching four feet long.
At the end of the gardening season people often ask if the tuberous roots of their ornamental sweet potatoes are edible. Sure they're edible, if you like the taste of cardboard. The ornamental ones are grown for their colorful leaves and not how the tuberous root tastes.
On a heartbreaking note I mark the passing of one of our vital friends of Master Gardeners. Steve Hartman was the devoted husband of Master Gardener Laura Hartman. Steve and Laura were the guiding force in our Master Gardener program's infancy and in the development of our Master Gardener Idea Garden. Next time you are in the Idea Garden stand in our iconic gazebo that Steve designed and built and be sure to look up. Steve was always the person looking up and looking forward to guide us by example to be better people and to be a better society.