Different types of impatiens flowers (Latin for "impatient) all share the characteristic for which they gained their name: even the slightest touch will cause their pods to burst and shoot seeds several feet from the parent plant. Consequently, species of the impatiens family sometimes are referred to as touch-me-nots. Horticulturists identify impatiens flowers as one of the most popular bedding plants in the country; they are beautiful, easy to grow and blossom abundantly in shade and without pruning.
Although primarily grown as annuals throughout the world, impatiens (also commonly called sultana) are a perennial in their homeland of East-Central Africa. Perhaps the best-known member of the family is Impatiens wallerana, which was discovered on Zanzibar in 1865 by Sir John Kirk, a member of Dr. David Livingstone's expedition to the island. Although first named I. sultana in honor of the Sultan of Zanzibar, it's name was eventually changed to I. wallerana to honor Horace Waller, a missionary who made sure that Livingstone's journal was published after the Scottish explorer died in Africa. The journal attracted attention to impatiens plants which were introduced to Costa Rica in 1880 but didn't become a star of the horticultural world until flower breeder Claude Hope discovered I. wallerana growing there as a weed around 1950. Hope began improving the lanky plant into the lovely groundcovers we know today.
There are more than 500 species in the genus Impatiens, including the rainforest species I. psittacina, known as the Thailand parrot flower. Unlike the periwinkle-like, single blossoms or rose-like blossoms of most I. wallerana, I. psittacina looks like a cream and lavender orchid. Sultana and New Guinea impatiens (I. hawkeri) are the species commonly grown for North American gardens. New Guineas have larger blossoms than sultanas and decorative bronze- and purple-tinted leaves with yellow or pink veins. Unlike sultanas, New Guinea impatiens plants prefer some direct sunlight. Morning light is best for them, so choose an east exposure.
Most garden impatiens range from 6 to 14 inches tall and spread a bit wider than their height. Their colors include red, orange, salmon, rose, pink, white, violet, and lavender blue. The backs of the blossoms have small nectar spurs that attract butterflies and hummingbirds.
Impatiens love moisture, but won't grow in standing water. They tolerate semi-arid climates, such as that of Colorado, if watered regularly. As with so many bedding and container plants, impatiens stays healthier and avoids attack by garden pests if not stressed by wilting and if planted in soil rich in organic matter. Mulch them for moisture retention.
Some gardeners have lots of success with sultanas reseeding, but dry, cold winters can make this difficult. As for New Guineas, although they can be grown from seed, they blossom more reliably when raised from cuttings. When planting sets, space small impatiens about 10 inches apart and leave 18 inches between tall plants.