Prune or cut back impatiens in midsummer if they cease blooming or become leggy. High temperatures, lack of adequate water during dry spells and lack of adequate fertilizer may result in a temporary drop of blooms, or they may cease blooming altogether. Pruning the plant revitalizes it and forces new blooms.
Use garden shears to trim the terminal ends of impatiens stems to form a rounded plant. Leggy plants benefit from cutting back to 4 to 6 inches. Not only does this force new blooms, it encourages vigorous growth of foliage as well, and forces the stems to branch out, creating a full, compact plant.
Maintain the shape of the plant by pinching out center leaves as they appear. This forces side shoot to emerge along the main stem. Reduce pinching once the plant develops the desired shape and allow to bloom. Deadhead blooms to prolong blooming.