Sweet Potato Vine Care

When a garden demands going big and bold, ornamental sweet potato vines (Ipomoea batatas) answer with Mardi Gras flamboyance. Unlike the sweet, starchy Thanksgiving Day vegetables, they're light on flavor and heavy on deep-purple, chartreuse, burgundy or multicolored flash. Perennials in U.S. Department of Agriculture plant hardiness zones 9 through 11 -- depending on cultivar -- and treated as annuals elsewhere, they reward minimal care with cascades of deeply lobed or heart-shaped leaves. Plant the vines as ground covers with plenty of room to roam, or spill them from walls, hanging baskets or containers. Just don't expect them to climb without support.

Enthusiastically growing sweet potato vines manage on minimal fertilizer. Give in-ground plants balanced, slow-release 10-10-10 fertilizer at planting and at two or three evenly spaced intervals between late spring and early fall. One brand recommends 1/2 tablespoon of its 10-10-10 fertilizer for each 1 square foot of soil. Wearing gloves and protective eyewear, spread the granules evenly, rake them into the top 2 or 3 inches of soil and water well. Fertilize container plants weekly with a 10-10-10 fertilizer and water solution mixed at one-fourth the label's recommended strength. If the brand calls for a monthly application of 1 teaspoon for each 1 gallon of water, for example, reduce the fertilizer amount to 1/4 teaspoon per gallon.

As tropical plants, ornamental sweet potato vines do best in warm, humid conditions and consistently moist -- not soggy -- soil. Their water-storing tubers carry them through brief dry spells. As general guidelines, water the vines thoroughly as soon as they begin wilting, or whenever the top 1 inch of soil feels dry to the touch. Check container vines twice daily in hot, dry weather, when the moisture evaporates quickly.

If the vines outgrow their boundaries, simply cut them back. The harder they're pruned, the more quickly they respond with lush, new foliage. Using clean, sharp hand pruners, prune the overgrown stems to the desired length about 1/4 inch above a leaf node. Two new stems replace each cut one, resulting in a bushier plant. To avoid spreading disease, disinfect your pruners by wiping them with a cloth soaked in rubbing alcohol between cuts and after finishing.

Pests and diseases seldom bother well-maintained ornamental sweet potatoes. Beetles occasionally chew holes in their leaves on their leaves, but seldom cause enough trouble to warrant treatment. Proper fertilizing and weed control deter red- or black-spotted, yellow tortoise beetles. Tweeze metallic-green Japanese or yellow-green, ladybug-lookalike cucumber beetles from the leaves and drown them in a bucket of soapy water. To kill high-jumping flea beetles, spray the vine until it drips with ready-to-use insecticidal soap. Repeat as necessary until they're gone. Wear gloves, long sleeves, long pants and eye protection when working with insecticidal soap.

Ornamental sweet potato doesn't survive prolonged sub-freezing temperatures. Frost kills the stems and foliage immediately, although the tubers survive until the ground freezes. To save a plant for another growing season, lift its tuber in fall before the first frost and store it in a dry area. In a frost-free climate, leave the plants in the ground all winter.