No genus in the garden is more diverse than Iris, and none has been more thoroughly worked over by horticulture. Species grow wild across North America, Europe, Africa, and Asia — in meadows, deserts, marshes, and mountain grasslands — and the garden varieties derived from them span nearly every color available to a flowering plant, including near-black and the murky blue-violets that approach blue more closely than almost any other genus can manage. The Greek goddess of the rainbow lent her name appropriately. In the garden, irises function as border plants, specimen clumps, cutting garden staples, and naturalizing perennials depending on species, and their sword-shaped foliage contributes structural value long after the blooms have finished.

The requirements vary considerably by type: some demand that rhizomes sit at or near the soil surface and bake in full sun; others prefer moist or even wet ground in partial shade. Most benefit from periodic division to prevent overcrowding and maintain vigor, and all should have their spent foliage removed once it deteriorates fully at season's end. Bearded types are reliably deer resistant. The genus rewards attention — a collection built thoughtfully across early, mid, and late-flowering species can hold interest for two months or more in spring, and selected species extend that into summer and fall.