Growing nearly identical to their edible cousins, ornamental sweet potatoes (Ipomoea batatas) have more brightly colored foliage in burgundy, deep burgundy-black, maroon, bright chartreuse and pink bi-color varieties. They are vigorous growers that do best in warm summer temperatures. Ornamental sweet potatoes are propagated from stem cuttings and are ready for planting out in just four to five weeks. They cannot not survive freezing temperatures, but tip cuttings can be taken in late summer and overwintered as potted plants indoors. Their color will be less vibrant in the lower light indoors, but they will bounce back when planted outdoors in spring.
Choose a site that is in full sun to grow ornamental sweet potatoes. If growing them in a container, ensure that the companion plants are also sun lovers and that the container is to be placed in full sun. Ornamental sweet potatoes grown in lower light levels lose some of their trademark colored foliage. Ipomea batatas are ideal planted at the edge of a container garden so their foliage can trail over the side of the container. The dark maroon varieties contrast well with variegated plants and brightly colored flowers, while the pinks of the Tricolor variety stand out when planted near pink or fuchsia flowers.
Ornamental sweet potatoes make excellent border plants for flower beds. They also make fast-growing ground covers in areas which don't require a permanent, perennial ground cover. Space plants at least two feet apart; they will quickly grow to cover the space between them.
Fertilizer and Cultivation
Fertilize ornamental sweet potato with a balanced, complete fertilizer at regular intervals throughout the growing season, or apply a slow-release fertilizer when planting and again six weeks later. Use a fertilizer labeled "10-10-10" or "20-20-20." Both of these contain equal parts of nitrogen, phosphorus and potassium, with the 10-10-10 fertilizer containing 10 percent by weight of each of these nutrients and the 20-20-20 fertilizer containing 20 percent by weight of each of these nutrients. The balance of the fertilizer is composed of trace minerals and filler materials.
Pinch the growing tips two weeks after planting and again two weeks later. This will help them to branch out and produce fuller, more lush-looking plants.
Cultivate them shallowly to control weeds; just like their edible cousins, ornamental sweet potatoes produce tubers from which the foliage gets its nutrients. Ornamental sweet potatoes benefit from a mulch if they are grown in the ground; mulch will reduce the growth of weeds and keep their roots cool.
Ornamental sweet potatoes are thirsty and should be watered the equivalent of an inch or more of rainfall per week. They will wilt if allowed to dry out, but will quickly rebound if given water right away.