New Guinea impatiens were first introduced into the United States in 1972 (Auburn University), and people quickly fell in love with the striking colors of the foliage and flowers. New Guinea impatiens prefer a fertile soil with lots of organic amendments and will thrive in a shady spot in your garden. Most are grown in clumps or groups in beds but they are also very attractive in hanging planters. There are certain problems involved with growing any plant, and New Guinea impatiens are no exception.
Most Cultivars Are Patented
According to horticulturists at North Carolina State University, most New Guinea impatiens cultivars are patented, and they advise against taking cuttings from any plant unless you are a licensed propagator or you are certain that the particular variety you are cutting is not patented.
A real problem for New Guinea Impatiens is the by-products of fertilizers that are left in the soil. Excess salt and micronutrients can cause numerous problems for the plant, even death. Most of these problems occur if the pH of the soil is incorrect. The ideal pH is a little on the acidic side, 6.1 to 6.5. Flush the soil with water after every third application of fertilizer to help with the buildup of salts.
Impatiens necrotic spot and tomato spotted wilt are common diseases of this plant. They are transmitted by the western flower thrips, one of the worst agricultural pests in the world. For some reason, it tends to attack the double-flowering variety more often. These infections cannot be cured and growers at the Connecticut Agricultural Experiment Station suggest getting rid of infected plants as soon as possible so as to not infect the rest of your impatiens.
Controlling the western flower thrips is of paramount importance. According to researchers at North Carolina State University, the best way to guard against this pest is to keep the planting area free of weeds and to make sure any soil you use in pots is sanitized. Should an infestation occur, there are commercial insecticides for control of the western flower thrips.