Plants are known to be cold hardy to at least -10°F.
Rudbeckia is advertised as heat and drought tolerant, but I have not found it so. I’ve found it to require at least weekly watering during the heat of the summer. A shortlived, southern native perennial, it likes the humidity and rain from southern climes. These very large and stunning composites may be worth your effort, just place within the correct hydrozone.
A non-invasive tansy from southern and central Europe for your low water-use bed and border that will reseed somewhat. A short lived perennial. Gray cut-leaf foliage provides an attractive white element in the garden.
I prefer dwarf chamisa to the full size species. Dwarf Chamisa fits better into home xeric areas and has green leaves, rather than gray or silvery. It's silvery stems combine well with its green foliage and yellow gold flowers. Although given the species and variety name "nauseosus" it has a pleasant fragrance. Dwarf chamisa blooms profusely in late summer and will readily re-seed.
The Arizona rosewood is classified either as a quite tall shrub or short to mid height tree. One of it's best features is that it is evergreen, with slender glossy green leaves approximately 3 inches long. It puts on small white flowers in summer. One of the few drought tolerant, native, evergreen trees available in the trade. Slow growing.
Two southern native hibiscus suitable for the medium to high water-use garden. Large green leaves are superseeded by very large and showy flowers. H. moscheutos is cold hardy and has some of the largest flowers, up to a foot across in red, rose and white, usually with a red eye. H. coccineus blooms scarlet 3 inch flowers -- not cold hardy but worth trying as a specimen container plant.
Buffalograss is North America's only native turfgrass, grows well in clay soils. A warm season grass that spreads by stolons, it is our best selection for low water-use lawns. It will survive very nicely on 15-20 inches of annual precipitation. For green turf summer long, a once a month watering is all that is needed. The common species is short to 4-8 inches, light gray/green to blue/green and goes dormant in fall, greening up again in May. Many newer varieties are being developed for wider blades and deeper green colors, such as Legacy® and Turffalo®.
Mahonia repans is one of my favorite plants with four seasons of interest. Low growing and spreading evergreen shrub is native throughout the Rocky Mountains. Bright yellow berries in spring are followed by black berries in summer and reddish winter foliage. The leaves are thick, glossy and holly shaped. Creeping Oregon grape holly prefers amended, humusy soil that replicates its native habitat as an understory plant in woodlands, but is low water-use once established. It will spread to cover an area, but not invasive. Very attractive!
Grayleaf cotoneaster is a wonderful low growing shrub for the xeric garden. Evergreen or semi-evergreen in colder winters, it provides good winter interest, along with the other seasons. Small oval shaped silver/gray leaves cover the many arching branches. Tiny white flowers appear in late spring followed by red berries in late fall and winter. Low water use once established.
Centranthus ruber is a versatile plant, able to be used almost anywhere in the landscape except full shade. Long blooming except during the heat of the summer. Deadhead after the spring bloom for better appearances. Reseeds some, but not a problem. Quite drought tolerant, it will still do nicely in medium and high water use areas, except for wet, soggy clay. It appreciates good drainage and moderate amending but will do well in poor soil. Centranthus ruber 'Alba' is a pleasant white blooming variety. Readily available at local nurseries.
Cranesbill belongs to the same Geraniaceae family as do the Pelargoniums, those red, hot house geraniums we all love. Both are perennials, however many cranesbill (referred to as the true geraniums) are cold hardy for us. Alpenglow is semi-evergreen, and evergreen in warm winters. Notice the intricate cut leaf patterns, which are much admired by myself and others. A good understory plant for the edge of a shady border.
Drought tolerant perennial with white cup shaped blooms usually found growing in poor soils. I planted it in heavily amended soil, and I think it was too rich for it. It was eaten up during the heat of the summer by flea beetles. I thought the too rich soil was the cause; however, Judith Phillips in Plants For Natural Gardens, wrote about this same occurrence in native soils. Phillips hypothesized this may be a way for tufted evening primrose to escape summer’s heat. However, my plant died, rather than just going to ground.
Salvia argentea is a first class drought tolerant biennial to add texture to your xeristrip. Light gray green tomentose (hairy) foliage adds contrast against accent rocks. This biennial will flower the second year, but I could do without the sticky, and somewhat unsightly stalk whose white flowers open in succession and quickly turn brown. Cutting off the stalks only encourages the plant to send up more sticky stalks. The leaves of the plant may appear to mimic Lamb’s Ears, however, they are not tough and resilient, tears easily, and are shredded by hail.
Thyme is known more for its use as an herb, but also makes an attractive and aromatic groundcover. Sometimes referred to as Thymus pseudolanuginosus, Thymus lanuginosus is a low water-use thyme for the hot dry areas that rarely flowers.
Chamisa or rabbitbrush is a medium tall shrub with blue-green stems that produce clusters of golden yellow flowers from September throughout fall, very showy in the landscape. Matted hairs on thin leaves cast a silvery appearance. Native throughout the southwest, in warmer climates it is evergreen. The official name has been changed to Ericamera nauseosa, but is still referred to as Chrysothamnus (meaning golden bush). Seeds prolifically -- is a good pass-along plant to friends, neighbors, relatives and passersby.
Arizona rosewood is one of the few native evergreen trees or tall shrubs that are low water-use. Underused in the Texas Panhandle, mostly due to lack of availability. But with searching in Albuquerque or Santa Fe, one should be able to locate a specimen. Faster growing than the Chisos rosewood. Long slender, serrated, glossy green leaves with white flowers in summer.
Cypress vine is a native annual tropical vine of the Americas, but has naturalized in Florida and the Gulf Coast areas; said to be cold hardy to Zone 6. Fine lacy or thread-like leaves twine as it grows, putting on scarlet red flowers in summer. In addition to being a climber, it can be used as a groundcover.
Sand lovegrass is a warm season bunch grass typically found in sandy soils east of the Rockies over a wide range of the U.S. The grass clumps themselves are usually 12-18" tall with the plumes rising to 3-4 feet. Will grow in clay and poorer soils. Very pleasing wispy, arching habit with a soft sway and rustle in the wind. Can grow in partial shade. Seed heads are somewhat purple, fine textured. Will reseed. Low or no water-use.
Oregon grape holly is an evergreen holly-like shrub native to the Pacific Northwest Rockies down into California. Upright, it is slow growing but can reach a height of 8 feet. Best when grown in shade, especially out of afternoon sun. Prefers a more humusy soil but will only required once a month watering when established, however, can also be placed in medium and high water-use areas. Bright yellow flowers in spring, followed by dark blue berries in summer. The thick, glossy, holly-like leaves have spines at the points. Leaves turn from green to red in winter.
Spring blooming crocus is a favorite among gardeners, heralding the end of winter. Many species of crocus can actually bloom in winter months. I've seen crocus bloom as early as mid Janurary, although February and March are more common. There are many different species of crocus, most people choose them by color, height or bloom period. Their colors range from yellow to purple, lavender, violet and white, some in combination of colors. Commonly, Crocus chrysanthus, C. venus, and C. angustifolius. C.
A good drought tolerant ground cover for use in a border, in a xeristrip or a rock garden. Evergreen grayish green leaves with fine hairs (tomentose). Will grow too tall and gangling in too rich and moist a soil. Some areas of the country have noted Cerastium tomentosum to be invasive, but I have not seen those tendencies here. A good substitute for the annual alyssium. Cerastium tomentosum var. columnae is a commonly available variety.
I love ornamental grasses and this grass tops my list. Blueish green evergreen leaves. A cool season clump forming, medium height grass. Treat it as medium water-use for the first year or two. Blue avena grass is not particular about soil, just as long as it’s well drained. After 2-3 years, blue avena grass will put out light tan oat-like plumes. This grass performs better in afternoon shade.
Oenothera macrocarpa, and O. missouriensis have been used interchangeably. Native over a wide range including the plains and wooded areas, carries the common name, Missouri evening primrose, bigfruit sundrops and Ozark Sundrops.
The flowers of Salvia darcyi are similar in appearance to Salvia greggii, however the shrub itself is more herbaceous than shrubby. I know of no common name for S. dacryi. Some sources say it is cold hardy to Zone 7, however it thrives in Denver Botanical Garden’s Zone 5. S. darcyi is native to the mountains of Northern Mexico and will do well in amended soil. Hummingbirds love it.
I have it planted in my xeristrip for a number of years. It will flower more vigorously with irrigation everyother week, when needed during hot drought years.
Veronica x ‘Blue Reflection’ should be an indispensable evergreen groundcover for you, as it has become for me.
Calamint, a member of the mint family, sparkles with white/pale lavender flowers in late summer into fall. Solid green foliage emits a pleasing mint fragrance. Attracts bees. Sometimes referred to as lesser calamint. Calamintha nepeta spp nepeta covers itself with light blue flowers.