New Guinea Impatiens (NGI), botanically Impatiens hawkeri cultivars, are vibrant bedding plants prized for their lush, dark foliage and strikingly large, colorful flowers. This hybrid group offers intense color throughout the season. Their popularity stems from their ability to tolerate more direct sunlight than their traditional counterparts, making them a versatile choice for containers and garden beds. The plant’s overall appearance is robust and tropical.
The Clumping Growth Habit
New Guinea Impatiens are definitively clumping plants, exhibiting a determinate, mounding growth habit rather than an aggressive spreading nature. They grow outward from a central base, forming a dense, rounded mound instead of sending out runners or rhizomes to colonize a larger area. NGI do not root along their stems when they touch the soil. The growth is primarily vertical and bushy, contributing to a compact, full appearance.
Depending on the specific cultivar, a mature plant typically reaches a height of 12 to 24 inches with a similar spread. This tidy, substantial structure makes NGI an excellent choice for containers or mass plantings where a uniform, predictable shape is desired.
Methods of Propagation
Since New Guinea Impatiens do not spread naturally by runners, commercial multiplication relies on vegetative propagation. Most modern NGI varieties are highly hybridized and often sterile, meaning they produce little to no viable seed. This sterility prevents them from self-seeding or spreading aggressively in a garden environment.
The most reliable method for creating new plants is through stem cuttings, a process that ensures the new plant is a genetic clone of the parent. Cuttings are typically taken from a healthy stem and rooted in water or a moist growing medium. For the typical home gardener, the lack of viable seed and runners means the plant will remain exactly where it was initially placed.
Distinguishing New Guinea from Common Impatiens
Confusion about spreading often arises from the growth habit of common impatiens, Impatiens walleriana. New Guinea Impatiens are easily identifiable by their elongated, lance-shaped leaves, which often display unique bronze, purple, or variegated coloration, contrasting with the smaller, lighter green leaves of the common variety.
A primary difference for gardeners is disease resistance. NGI are highly resistant to Impatiens Downy Mildew, a devastating fungal disease that wiped out many populations of I. walleriana globally. Additionally, while common impatiens prefer deep shade, NGI can handle partial sun, though they benefit from protection during the hottest afternoon hours. The traditional impatiens is also an aggressive self-seeder, scattering its seeds widely, which is the likely source of the concern about NGI spreading.