Some of the showiest perennial native plants you can grow in a drought tolerant (Mediterranean, Xeriscape) garden are the native iris species and their hybrids. Recent hybridizing efforts have yielded some wonderful easy care plants for the garden. Mainly derived from coastal and foothill species like Iris douglasiana, I. innominata, I. tenax, I. munzii, etc. They hybridizer’s hand has given gardeners some truly showy and spectacular perennials for the dry garden landscape (and well watered gardens also). Low clumps of grassy evergreen foliage cloth the plant year round, and in late winter, into spring, numberous stems produce some of the showiest of native blooms. The typical iris type flowers (upright petals called standards, and often wider petals which hold themselves on the horizontal to pendulous aspect and are known as falls) and the newere floral shape which is plate like, with all petals tending to lie on the horizontal plane and often widening to give a ‘fuller’ flower appearance. (these resemble flat plates, or dishes, and are similar in floral form to many irises of the Louisiana and Japanese groups). Dark narrow foliage is shiny above and tends to arch. There are also dwarf selections which resemble clumps of grass very much. Branching of the flower stems occurs in many cvs. to increase the total number of blooms per clump and they bloom for a much longer period or in larger quantities than what is typically expected. Most have 2 blooms per stem in the species and old hybrids. Flower color (Iris are named after the goddes of the rainbow) due to their broad color spectrum. Many shades of blues to purples, yellows, violets, lavendars, reddish tones which can be dark maroon and pinkish buff tones, and whites. The many combinations of complimentary and contrasting colors is truly amazing! Here you can find 2-3 colors or more in each bloom. The patterns of color on the petals is dazzling! You can have a yellow signal area on the falls (this is the attractive color pattern to bees), picotees, splashes and veining patterns, blotches on the falls which surround the signal can be quite dramatic, especially if the contrast in colors is bold. (some of my favorites are light blue with a dark blue/purple splash of color to give eye catching contrast. Similarly, you can find yellows (more likely brilliant golds, veined in dark browns, or patterned with dark browns), These are only some of the combinations of color which create a riot of color to each bloom/ not to mention in the garden. you can also get pastels and very deep color tones in a wide array.
A list of several named cvs. will follow, as well as non named but color selected forms which are propagated, so you can find them and include them in your garden color scheme.
Basic culture is simple and easy. They like well drained soil. (*many species come from hills or slopes). Partial shade is tolerated by all, and some heat and moisture sensitive cvs. require this, especially in hot sun/summer climates. (too wet soil conditions accompanied with high temps can rot the rhizomes and kill the plant) It is recommended that in hot summer areas, they be planted in partial shade. Although drought tolerant (especially in the wild), they need additional watering during the growing season for best appearance. These plants come from the understory of trees and larger shrubs(so they get that shade requirement by association in plantings in the wild from Nature.) Just keeping the heat of the sun during the hottest time of day off the plants where summers are very hot will give them the shade they like. Grooming and maintenance are minimal for these plants. You just clean dead foliage and spent flower stems. The clumps live for many years without any particulat attention beyond that and you get wonderfully profuse blooming dependably. The oliage can grow to 18″ but usually under 1 ft (dwarf cvs are even shorter, perhaps 4-6″ tall.) I like this iris group very much since they clumps remain attractive (and carefree) while out of bloom).
Fertilizer needs are minimal, especially if you have reasonably fertile soil. Any good all purpose fertilizer works well for these. In coastal situations, these iris are almost drought tolerant entirely, needing only the winter rains to supply their water needs. (fog and mist drip supply moisture to the plants from their taller companion plants (trees and shrubs) which drip moisture down onto them. These are easy care, dependable perennials for any landscape. There are many named cvs. available, but not many pictures of them, so you have to see them in person to decide which ones you like best!