New Guinea impatiens are a cultivar of the species Impatiens hawkeri. They can grow up to 60 cm (2 feet) in height and produce flowers in a myriad of colours including pink, white, orange, purple and red. The foliage is ornamental as well, and can be green, bronze, or purple in colour. New Guinea impatiens bloom from early summer to early autumn.
Plant New Guinea impatiens just after the final frost of winter. Choose a location that receives full morning sun and partial shade in the afternoon, or the impatiens will wilt. Spread a 2.5 cm (1 inch) layer of organic compost over the soil prior to planting and use a garden tiller to incorporate it into the soil to increase fertility and drainage.
Water New Guinea impatiens three times a week for the first month of growth. Reduce the frequency of watering to twice per week during spring, summer and autumn.
Feed New Guinea impatiens twice per year, once in early spring to encourage new growth and again in midsummer to increase flower production. Use a 5-10-10 NPK fertiliser, as too much nitrogen can result in excessive foliage. Follow the instructions provided by the manufacturer for proper dosage.
Spread a 5 cm (2-inch) layer of mulch over the soil surrounding New Guinea impatiens. Start the band of mulch about 5 cm (2 inches) away from the stem of the impatiens to allow room for growth. Refresh the layer of mulch when it becomes visibly deteriorated.
Remove faded or dying flowers as soon as possible to encourage the growth of new blossoms. Dead flowers are used to form seeds, and they will sap nutrients from the rest of the plant. Pinch the flowers off as close to the stem as possible to prevent damaging the impatiens.
New Guinea impatiens can be grown from seed, but are most easily started from a seedling. Purchase seedlings from a lawn and garden store or plant nursery in early spring. Shredded cedar mulch is ideal for New Guinea impatiens, as it provides maximum moisture conservation and has mild pest repellent properties.