Of the hundreds of species, only the following are usually seen in gardens. Most of these are annuals or tender perennials treated as annuals; all are valuable for long bloom period (most flower in summer, and a few continue into fall). When lightly touched, ripe seed capsules burst open and scatter seeds.
I. balfourii. Annual. From the Himalayas. To 20 in. high and broad, with 4- to 5-in. leaves and loose clusters of inch-wide, pink- tinted white flowers. Seldom planted but often pops up unannounced. It can become a pest by reseeding, but it is attractive in shady, informal plantings.
I. balsamina. BALSAM. Annual. From Southeast Asia. Erect, branching plant reaches 830 in. high and 68 in. wide. Sharp-pointed, 112- to 6-in.-long leaves with deeply toothed edges. Large, spurred flowers are borne among leaves along main stem, branches; they may be solid colored or variegated, in white or shades of pink, rose, lilac, or red. Compact, double camelliaflowered forms are most frequently grown. Sow seeds in flats or pots in early spring; after frost danger is past, set out young plants (or purchased transplants) in full sun (light shade in hottest climates).
I. capensis. JEWEL WEED. Annual. Native to damp, shady sites in Canada and the northern U.S. Grows 25 ft. tall, 2 ft. wide. Smooth, tooth-edged, green leaves to 312 in. long. Spurred, 1-in. orange-yellow flowers with reddish brown splotches; blooms in summer, fall. Partial or full shade. Juice from crushed stems is used to treat dermatitis caused by poison ivy, poison oak.
I. New Guinea hybrids. Perennials in Zone TS; USDA 10-11; annuals anywhere. A varied group of striking plants developed from a number of species native to New Guinea, especially I. hawkeri. Plants can be upright or spreading; most are 12 ft. tall and as wide or wider. Leaves are typically large, often variegated with cream or red. Flowers usually large (212 in. wide) though not profuse, held well above foliage; colors include lavender, purple, pink, red, orange, and white. Once considered primarily potted plants, they also perform well as bedding plants; provide ample fertilizer and give somewhat more sun than you would I. walleriana.
Popular strains include 'Celebration' (with 3-in. flowers), 'Paradise', 'Sunshine', and 'Pure Beauty'. Most New Guinea hybrids are cutting-grown plants, but 'Spectra' ('Firelake') and 'Java' strains can be grown from seed. 'Spectra' offers a mix of flower colors and has leaves variegated with cream or white; bronze-leafed 'Java' is available in single or mixed colors. 'Tango', also seed grown, has bright orange blooms and bronze-green foliage.
SunPatiens strain is the result of a cross between New Guinea hybrids and a wild species. These are long-lived, free-blooming plants that can take full sun in all but the hottest areas. Flower colors range from pinks and reds through coral and orange and white. Three form-based series are offered: Compact (upright and bushy, to 23 ft. tall and wide); Spreading (mounding growth to 23 ft. tall and 3 ft. wide); and Vigorous (vase-shaped, 34 ft. tall and 3 ft. wide).
I. omeiana. HARDY IMPATIENS. Perennial in Zones US, MS, LS, CS; USDA 6-9. From mountainous areas of China. To 1112 ft. high, spreading by runners. Primarily grown for its attractive leaves that grow to 112 in. long and are velvety dark green with a whitish stripe down the center. Blooms in early fall, bearing small yellow to apricot flowers that resemble little goldfish. Partial or full shade.
I. repens. YELLOW IMPATIENS. Perennial in Zone TS; USDA 10-11, usually grown as annual. From India, Sri Lanka. To 8 in. high, 1 ft. wide, with thick reddish stems and kidney-shaped, 1-in., green leaves. Hooded, clear yellow, 112-in. flowers from summer to fall. Good choice for hanging baskets. Partial shade.
I. sodenii. POOR MAN'S RHODODENDRON. Perennial in Zone TS; USDA 10-11; indoor/outdoor plant elsewhere. From eastern tropical Africa. To 48 ft. tall, 10 ft. wide, with woody-based stems clothed in whorls of 8-in.-long, glossy, dark green leaves. Produces many 212-in., slender-spurred flowers in lilac, pale lavender, or pinkish shades. Tolerates seacoast conditions. Frosts kill it to ground, but it regrows in spring. Blooms in partial or deep shade; takes sun in cool-summer areas. 'Flash' has white blooms streaked with bright rose-pink. 'Madonna' has pure white flowers.
I. walleriana. IMPATIENS, SULTANA. Perennial in Zone TS; USDA 10-11, annual anywhere. The South's most popular flowers for partial or full shade; will take full sun if watered frequently almost daily. Rapid, vigorous growth; tall types reach 2 ft. high, dwarf kinds 612 in. high. Narrow, glossy, dark green, 1- to 3-in.-long leaves on juicy pale green stems. Flowers 12 in. wide, in all colors but yellow and true blue. All types are useful for many months of bright color. Grow plants from seed or cuttings, or buy them in cell packs or pots. Space taller types 1 ft. apart, dwarfs 6 in. apart. If plants overgrow, cut them back to 6 in. above groundit's a tonic. New growth emerges in a few days, and flowers cover it in 2 weeks. Plants often reseed in moist ground.
At any given moment, there are dozens of excellent strains on the market; many are just nuanced versions of the others. Following are some of the more popular.
Accent. To 10 in. high, in numer- ous individual colors or a mix.
Blitz. To 16 in. high, with 2-in. flowers in mixed or single colors.
Dazzler. To 11 in. high, in all colors plus a star pattern.
Super Elfin. To 810 in. high. Comes in an exceptionally wide range of individual colors and blends of harmonizing hues. One example is 'Blue Pearl', with flowers in an unusual bluish lilac shade.
Swirl. To 1012 in. high. Pastel shades with picotee edges of deeper color.
Many novelty strains and selections are available. They include 'Firefly', dwarf series to 68 in. high, with 12-in. flowers in the full range of impatiens colors; 'Confection', 1012 in., producing a high percentage of double and semidouble flowers from seed; and 'Victorian Rose', 1012 in., with frilly, rose-pink, semidouble flowers. Other double impatiens with flowers resembling rosebuds include cutting-grown 'Fiesta', 'Rockapulco', and 'Tioga' strains. The double-flowered types are best used as potted plants, located where flower detail can be observed close up.