Popular in gardens across the world, the iris is a flowering genus that contains several hundred species. Named "rainbow" in Greek, the iris plant comes in just about every color imaginable. There are a number of species of iris plants, some more tolerant of cold or heat than others, but all of which have something distinct to offer the home garden.
A native of Southern Europe and the Mediterranean, bearded iris (Iris germanica), also called German iris, is an extremely hardy and easy-to-grow species of iris that can be found growing in gardens as well as abandoned lots and roadsides. The plant boasts small hairs at the base of its petals, hence the title "bearded" iris. Bearded iris will grow in a range of conditions, and the plant can be grown with ease in USDA zones 4 to 10. Bearded iris isn't picky about soil and will grow in just about any soil type so long as it has a good day's worth of sun. Fairly drought tolerant once fully grown, bearded iris should be watered only as needed.
Dwarf Crested Iris
Dwarf crested iris (Iris cristata) is a demure member of the iris family, reaching a maximum height of only 5 to 11 inches. A native of the United States, dwarf crested iris grows best in USDA zones 5A to 9A, in partial sun or full sun. The plant prefers soils that are well drained and either acidic or neutral. Dwarf crested iris is moderately drought tolerant once established and can be watered as needed.
A native of Kenya and Eastern Africa, African iris (Dietes iridioides) has a distinctly different appearance than many other iris species, boasting three pronged petals and long, grass like leaves. Also called "fortnight lilies," the plant tends to bloom in clusters every two weeks or so. The plant grows best in USDA zones 8 to 10, in soil that is well drained and moist. African iris will grow in poor soils if watered frequently, but the plant isn't well suited to salty coastal gardens.
The Louisiana iris (Iris Louisiana hybrids) is a garden hybrid notable for its ability to tolerate wet soils, thriving even in standing water. Also called a "water iris," the Louisiana iris is a versatile plant ideal for pond sides or bogs. Louisiana iris boasts floppy flower heads in just about every color, including blue. The plant grows best in wet soils, in USDA zones 5 to 10. Louisiana iris will grow in full sun or shade, but will require considerably more water if grown in full sunlight.