The flowering potato plant, Solanum rantonnetii, is an evergreen shrub that is native to areas of South America. The shrub is a compact, multibranched variety that grows well as a border or container plant. Flowering potato shrubs are deer-resistant and should be protected from frost, as the plant is sensitive to cold temperatures.
The flowering potato plant is a tropical evergreen shrub that grows to a height and width of 8 feet. The shrub produces dark green foliage with flowers that bloom from midsummer to mid-fall in blue, purple and yellow. Flowers that are spent turn into decorative berries in the fall.
Flowering potato shrubs are hardy to plant in USDA growing zones 10 and 11 in a soil that is well-draining. A sandy-loam or clay-loam soil with full sun exposure is preferred. The soil pH should be tested to verify it is neutral with a pH of 7 to 8. Ground rock sulfur can be worked into the soil to lower the pH number, or limestone can be added to raise the pH number.
The flowering potato shrub requires a soil that remains moist during the growing season. Supplemental water should be provided when the weekly rainfall amounts are less than 1 inch during the summer months. Provide a deep soaking to a soil depth of 10 inches, as this will promote deep root growth. Mulch can be applied around the root ball of the plant to assist with moisture retention. A water-soluble, balanced fertilizer should be applied every two weeks from late spring through summer to promote healthy foliage growth and flower production.
Flowering potato shrubs can be propagated by taking softwood cuttings in early summer. The cuttings are taken from new branch growth that is beginning to harden and will snap when bent in half. The cut end of the stem should be dipped into rooting hormone and stuck into a rooting tray filled with water-moistened rooting medium to produce roots. The stems can be transplanted to individual growing containers once the roots reach a length of 1 inch.
The flowering potato shrub should be monitored for the presence of an insect infestation of thrips or aphids. The insects will damage the shrub as they feed on the foliage. The insects should be removed from the shrub by spraying it with a sharp stream of water. An application of insecticidal soap on the top and underside of the leaves will prevent the insects from returning.