The blue potato bush (Solanum rantonnetii), also known as Paraguay nightshade, is a shrub native to both Brazil and Paraguay. This plant develops bluish-purple blooms with yellow middles during summer and continues to flower into fall. The blue potato bush can grow up to 8 feet tall and 6 feet in diameter. It is hardy in USDA zones 9 through 11 and can survive temperature dips as low as 23 degrees F.
Prepare a planting location by pulling all grass and weeds and removing any large rocks. Dig a hole that is slightly larger and the same depth as the pot that the blue potato bush is growing in. Mix 3 inches of organic compost with the turned soil to add nutrients.
Place the root ball into the hole and replace the soil. Tamp down firmly to remove air pockets and water until the soil is well-moistened.
Water whenever the top inch of soil is dry to the touch. Feed the bush once a month with a water-soluble fertilizer mixed according to package directions.
Prune the bush in early spring to remove damaged limbs and to keep growth in check.