Potato plants are grown for their edible underground tuber, but several species and cultivars are grown purely for their decoratively colored foliage. Edible potato plants are pruned only at the end of the season before harvesting of the tubers because the leaves are needed to capture light and grow the tuber. Ornamental species, such as Ipomoea, can be pruned aggressively throughout the growing season to suit the planting location or garden design and will branch and grow again almost immediately, according to the University of Florida.
Prune your edible potato plants only after the tuber is mature, which is 80 to 115 days after planting, according to the University of Florida.
Shear off the live or dead foliage down to the soil line with a sharp garden knife or pruning shears and compost or discard the plant tops. The potatoes should be held in the ground for two to three weeks after the top foliage has been severed and removed.
Cut back your ornamental potato vines as needed from spring through fall to control the size or shape of the plant. Prune regularly and aggressively to increase the fullness and bushiness of the plant as branching will occur at most cut sites. Prune less if you want longer, more vine-like lengths of decorative foliage. The plants grow quickly.
Shear off and discard the dead plant foliage that occurs naturally after the first frost in fall or winter. Cut down to the soil line or roughly an inch above. In some warm climates ornamental potato vines can grow year-round and will require ongoing pruning.