USDA Hardiness Zone 6

Plants are known to be cold hardy to at least -10°F.

Other Cold Hardiness categories

Common Name: Jupiter's Beard, Red Valerian

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.

Common Name: Alpenglow geranium.

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.

Common Name: White Tufted Evening Primrose

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.

Common Name: Silver Sage

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.

Common Name: Thyme

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.

Common Name: Chamisa, Rabbitbrush

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.

Common Name: Arizona Rosewood

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.

Common Name: Honeysuckle, yellow

Yellow honeysuckle is a much better choice, along with Loncera sempervivens, than the traditional and invasive Japanese honeysuckle usually sold. Fragrant and yellow blooming, a good climber and groundcover. Average garden soils with low and medium water-use. Can be low water-use once established.

Common Name: Switchgrass

Switchgrass is one of the best native ornamental grasses of our tall prairies. Switchgrass forms upright bunches of wide 1/2 inch green blades, with open pale purple inflorescence arising another 2 feet in late summer to fall. Switchgrass will thrive with every other week supplemental irrigation. There are many varieties of switchgrass, 'Prairie Sky' is the most drought tolerant (low, xeric) with blue blades. Other fine selections are 'Heavy Metal' with metallic lavender blue foliage turning reddish towards fall, and 'Shenandoah' with leaf blades tipped in red.

Common Name: Gray Santolina, Lavender Cotton

Lavender cotton, or gray santolina is a low mounding woody subshrub that should live on the lean side. Not that it won't overgrow if fed. It will maintain its compact shape in poorer soils without amending or fertilizing. Small silver gray leaves cover the shrub. Tiny yellow button flowers appear in summer. Evergreen, the santolinas are native to the Mediterranean area. Aromatic and edible, it's leaves were used as a flavoring in broths, sauces and grain dishes. Low water-use.

Common Name: Daffodils, Jonquils, Narcissus

Daffodils are the most notable of the spring bulbs. Reliable from year to year, daffodils can be depended upon to bloom even when faced with late season blizzards and are unpalatable to deer and squirrels. Daffodils aren't too particular about soil, but do better in amended soil, planted about 4 inches deep in November and December. Typical bloom times are February through April, depending on the variety, and there are thousands of varieties to choose from.

Common Name: Snow in Summer

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.

Common Name: Blue Avena Grass, blue oat grass

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.

Common Name: Missouri Evening Primrose, Bigfruit evening-primrose, Ozark Sundrops

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. 

Common Name: Salvia darcyi

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.

Common Name: Calamint

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.

Common Name: Hyssop, Hummingbird Mint, Licorice Mint

Agastaches are some of the Southwest's showiest natives and one of our native perennials where must breeding and hybridization is being done. Native to slightly higher elevations that 3600 ft., it requires either afternoon shade or medium water-use. It has not been reliable in coming back for me, but it has for others. Well drained soil is a must. Nonetheless, it is easy to be seduced by its masses of blooms and alluring fragrances. Hummingbirds certainly are entranced.

Common Name: Honeysuckle, coral

Another American native vine, evergreen in more southern climates than ours, but cold hardy here. Fragrant and attractive coral flowers in spring and early summer. Attracts birds, butterflies and hummingbirds. Pleasant glossy green leaves. Not invasive. Medium water-use.

Common Name: Alkali sacaton

Alkali sacaton is a perennial warm season bunch grass native to the Southwest. In late summer to fall, airy triangular seed heads wave above the silver green grass blades. Grows in alkali soils, many say in locations where there is moisture nearby, prefering heavy clay soils. It is quite drought tolerant once established, and long lived. It will, of course, grow bigger or smaller depending on water resources.

Common Name: Green Santolina

Green santolina is an evergreen shrub native to the Mediterranean region. Its grass-green color makes it a welcome addition to any landscape. Medium and low water use, cold hardy, sun and heat tolerant, it prefers poorer soil. Aromatic green leaves that resemble those of the cypress. Yellow button flowers in summer.

Common Name: Mat Daisy, Atlas Daisy

Mat daisy is a low growing spring blooming plant. Drought tolerant. Not exactly a groundcover, as the top growth disappears during summer and reemerges as a green basal rosette in fall, getting ready to bloom again in the spring. Blooms late March to May with small white daisy-like flowers that have pink undersides. Forms a compact ground-hugging mat. Will self seed some, but never invasively.

Common Name: Sweet Autumn Clematis

Although usually sold as Clemantis paniculata, it could be C. terniflora. Sweetly fragrant, low water-use vigorous growing vine for great late summer display. Creamy white flowers form silvery seed heads.  Cut back in spring as it blooms on new growth.

Common Name: Hybrid Daylilies

Green sword-like foliage with striking bell or funnel shaped flowers that last only a day. Hundreds of different hybrids and cultivars in a wide range of colors, some early, mid and late summer blooming. Daylilies do better in medium, well-amended soil and a sunny location that enjoys afternoon shade, but they are versatile. Daylily leaves may exhibit alkalinity in clay soil. If this is the case, amend well with organic matter.

Common Name: Silver Blade Missouri Evening Primrose

Gorgeous! Luscious goblet shaped lemon yellow flowers on this native wildflower that also develops elongated seed capsules. The lighter, silvery sheen of the leaves distinguishes the O. macrocarpa var. incana subspecies, and is also an evening to morning bloomer.

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