Plants are known to be cold hardy to at least 0°F.
Mexican blue sage is a native of Mexico and in many references labels it cold hardy to USDA Zone 8, however, it has wintered over in Amarillo many years now, even in full northern exposure. It has died back to the ground once or twice, but comes back up from the roots. If good to well drained soil is provided, it should do fine. And I hope you can provide that, as Mexican blue sage is one of my top plants to include in xeric gardens. True bright blue flowers bloom summer and fall with once a month watering. Butterflies are attracted to it. Indispensable.
Big Bend silverleaf is the most cold hardy of the Leucophyllums and has wintered over in Amarillo, Zone 7, for 5 years so far. Possibly cold hardy to Zone 6. It is hard to beat a more attractive summer blooming shrub for small xeric spaces. After summer rainfalls, Big Bend silverleaf, native to the Big Bend National Park area, becomes covered in silver blue flowers that twinkle like jewels among its silvery gray leaves. Hard to find, it's worth searching for.
Agaves are striking and architectural Southwest native plants and are included in a group of plants I term Southwest evergreens. They are unusual in that at maturity, they only flower once, and then die. for this reason, some classify them as multiannual, rather than perennial. However, as they common name suggests, it takes many years before they flower. Leaves of the Agave are arranged in a spiral beginning from a near invisible stem, forming a rosette.Agaves vary in size from 4-6 inches to larger than man-size.
Not all succulents are cacti, nearly all cacti are succulents (a few exceptions). Nearly all cactus species are native to the Americas, providing a prickly evergreen presence. There are many cactus that are cold hardy for the Texas Panhandle. There might be one for your garden.
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.
Maypop, or passion vine, is a perennial vine native to eastern and southern areas of the U.S. In the South, maypop grows into a woody vine, but in northern areas like the Texas Panhandle, it will die back to the ground. Lobed, dark green leaves, beautiful, unique flowers emerge in the summer to fall, producing edible fruit. Maypop will sucker, especially when ample watering is present. Passion vine, the most cold hardy of the genus, should be cold hardy to Zone 6.
An old world Mediterranean plant best known for the acanthus leaf shape used as a basis in classical Greek and Roman designs. The plant itself takes 2 – 3 years growth before flowering. Attractive flowers with purple bracts on tall spikes to 4’. Frost sensitive, will die back in a late spring frost, but will come back. Adds architectural and textural interest.
It is so refreshing to see the rain lilies bloom after a long hot summer. Whenever they begin to bloom, I know the worst heat is over. Rain lilies are a delightful flower that sends up glossy green, grass-like leaves from its bulb in late spring. In mid to late summer, pure white flowers resembling a crocus open and continue through September, usually after a good summer rainfall. There are quite a few species and varieties (of various colors) of Zephrantes, however, Z. candida is the only rain lily cold hardy in Amarillo. I've grown it successfully since 2008.
Herbaceous perennial. Fragrant hummingbird plant belonging to the mint family (Lamiaceae). Limited reseeding. Does better in afternoon shade. Locate in a transition area between medium and low water use. Leave plant and flower stalks standing in the fall, the plant does better trimmed back at the beginning of March.
Turpentine shrub is an evergreen shrub native to the southern parts of the Southwest, and only marginally cold hardy on the Caprock. It will survive when in a sheltered location and soil with excellent drainage, along rocky cliffs, outcrops and arroyos. Avoid compact clay soil, or amend clay soil very well for drainage with inorganic amendments. Yellow autumn flowers.
A native to Texas, flame acanthus loves the heat and full sun! A hummingbird and butterfly plant. Does well in poor soil. May only be cold hardy to Zone 7, however, it has come back for several years in the Panhandle. Grows rapidly and will flower the first year, if you must replant, this is still a good choice for mid to late summer and autumn flowers. Re-seeds some, transplant them early as their roots grow deep.There is another variety with light pumpkin colored flowers, but this one does not bloom as prolificly.
Yaupon holly is a tall shrub or a small tree growing typically to 8-12 feet in the Texas Panhandle. Cold hardy to Zone 7 (still best to plant in a protected location), it prefers partial shade, especially afternoon shade. Low (once established) to high water use. Small leathery, glossy, evergreen, dark green leaves (to 1.5” long) have toothed margins on dense branching. Insignificant greenish white flowers in springtime followed by red berries in the fall. Female plants require a male plant to pollinate and bear fruit (dioecious). Attractive tall, traditional looking shrub.
Heucheras are native to the North American continent and make wonderful foliage and flower plants for your woodland border. Grown mostly for its interesting, evergreen foliage, coral bells will continue to flower on mature plants if kept deadheaded into the summer. Although the native heucheras are great in themselves, there are hundreds of hybrid cultivars to choose from.
Beautiful xeric sage with aromatic soft gray green leaves, mostly evergreen. Summer to fall blooming with mauve/purple sticky but fragrant flowers. Takes a few years to reach mature height. Requires good drainage and dry soil in the winter. A Plant Select® Plant. Native to California and will grow in the High Desert regions. Cold hardy to Zone 5 and quite heat tolerant.
Yuccas for Texas High Plains Landscapes
Hyacinths are a much loved and very fragrant spring bulb, flowering in March and early April in our area. Clusters of bell-like flowers dangle from a central stem. Native to Asia, hyacinths were one of the early favored flowers by the Persians, Turks and Europeans, in fact, practically everyone who came in contact with them. Easy to grow in full sun to part shade in average garden soil. Hyacinths come in many pastel colors, both single and double flowers.
Black dalea, an autumn blooming southwest native shrub, should be used more in the home xeric landscape. Growing only to about 3 feet, black dalea spreads out with thin, wiry branches and small, green, compound leaves. The shrub becomes completely covered with tiny purple flowers as to be enshrouded in a purple cloud.
Many references are unsure of its cold hardiness to zero, and it had thrived nicely in my city garden in Amarillo. However, it does not seem to be reliably cold hardy. It's a beautiful shrub that provides stunning late fall color that is worth replanting.
Dark green, semi-evergreen aromatic leaves are the feature most prized, along with the tiny yellow daisy-like flowers that bloom spring to fall. Damianita prefers full sun and lean soil and does well in heat and temperatures to zero degrees. Daminaita will lose its leaves in cold winters.
Dasylirion is one of the plants I call a southwest evergreen. Different in appearance from traditional evergreen shrubs, it fulfills the same purpose in native and xeric landscapes. Symmetrical rosette of narrow leaf blades or leaves emanating from the center of the rosette. Barbs lining the margins of the thick pale green leaves give Dasylirion another common name, sawtooth yucca. As Sotol ages, a trunk may form under the rosette and even multiple heads may develop. At maturity, an 8-10 foot tall flower spike ascends from the center where thousands of small creamy white flowers open.
Summer flowering low water-use native tree, several varieties to choose from. Willow like green leaves. Cold hardy reliably in Zone 7, will winter over most years in Zone 6. The variety pictured in the close-up flower photo is "Lucrecia Hamilton", the variety in the third photo is 'Art's Seedless'. During early autumn snows, be quick to shake snow off the branches to avoid breakage.
Warm season native clumping ornamental grass that is well suited to the transition zone between turf and flower bed. Medium to blueish green thin grass blades form a low to medium size clump, medium water-use zone. In late September, it sends plumes upward that give the appearance of a deep pink haze or mist. There are several new selections of Gulf Coast muhly, thankfully, to choose from. Be sure to pay attention to the cold hardiness for your area and you won't be disappointed.