How to Care for a Purple Flower Potato Bush

Grow the potato bush in full sun for the maximum amount of flowers.

Avoid allowing the soil to dry between waterings. Although the purple flower potato bush is somewhat drought-tolerant, it is at its most attractive -- and better able to fight off disease pathogens -- when it is watered consistently. Provide it with at least one inch of water a week if it doesn't rain.

Fertilize the shrub in spring when you first see new growth. Use an all-purpose shrub fertilizer, such as a 10-10-10, at the rate suggested for the size of your potato bush. Sprinkle the granules on the soil in an area three inches from the base of the shrub to three inches outside the drip zone, and water it to a depth of six inches.

Prune the purple flower potato bush immediately after the blooming period. Cut out all dead, diseased and weak branches. Make the cuts flush to their points of origin without cutting into the branch collar -- the protruding area where the growth meets the trunk. Determine how tall and wide you want the potato bush to grow the following season and cut both the top of the bush and lateral branches back six inches less than that.