A perennial plant is a plant that requires one or more years to reproduce and usually continues living, but not indefinitely. Whether a plant is cold hardy or not is not connected to being an annual, perennial or biennial.
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.
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.
Illinois bundleflower should be grown for its unusual characteristics of seedpods and leaves, if nothing else. A member of the legume or bean family, the seed pods turn dark brown, leathery and twisted in appearance and rattle in the wind in late fall. The compound, alternate, pinnate leaves fold when touched or when exposed to strong sunlight. Small white flowers in summer. Attracts butterflies, birds love its seeds. The plant can grow to be quite large if in high water-use areas.
Western ironweed is a prairie native to the Great Plains states. Mid-summer to fall deep purple flowers clusters appear at the top of stalks. Ironweed can be invasive, rooting madly down to a foot so control could be difficult. Drought tolerant and cold hardy for the right location.
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.
Three leaf sumac is medium height woody shrub native to the Texas Panhandle and throughout the Southwest. Three distinctive cleft and lobed leaves (trifoliate) are medium to dark green. Small greenish yellow flowers in spring are followed by tart red berries in summer, which are used to make a lemonade-like drink. The shrub's flowers have a pleasant fragrance, even though it is called skunkbush by some. Beautiful golden and reddish fall foliage. Cold hardy to Zone 4, yet extremely heat and drought tolerant. Prefers sandy and well drained soils.
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.
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.
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.
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.
There are several varieties of Salvia guaranitica that range in shades of blue from light to dark. As with most of the tube-shaped salvia flowers, S. guaranitica is a hummingbird magnet.
Native to South America, S. guaranitica is not zoned cold hardy for the Texas Panhandle, but it has wintered over in protected Amarillo gardens in many locations for many years. It has wintered over for me at least 5 years, unprotected. Deadheading is not required.
Most gardeners’ acquaintance with veronicas is with the Veronica spicatas, ‘Red Fox’, ‘Icicle’, and ‘Sunny Border Blue’; the tall, spiky red, white and blue medium and high water-use veronicas. But consider the low water-use option, V. incana. Deadhead to prolong the blooms and water deeply once a month, once established in well-drained soil. The gray-green leaves should be a give-away by now as to its water requirements.
Victoria blue salvia is usually not cold hardy in the Texas Panhandle, but every once in awhile, one will winter over. But that shouldn't stop you from replanting this lovely, summer long blooming native to regions further south, classified by some to be one of the top ten flowers for Texas gardens. Upright and dense flower stalks in blue, white (Alba) and deep blue or violet. Salvia farinacea continues to be hybridized to create new introductions. Often referred to as mealycup sage, its stately appearance deserves the nobler moniker, Victoria Blue.
Texas red yucca is technically not a yucca, but has many of the same qualities as yuccas. Thick, succulent dark olive green leaves grow out of the base, as it is stemless. The coral red flowers appear at the top of a long raceme, often 4-6 feet tall. 'Yellow' and 'Red' blooming yuccas are also available. Although it's natural range is north eastern Mexico and West Texas, it is cold hardy throughout much of the Southwest. Allow for sharp drainage in moister climates to prevent root rot.
Gregg's mist flower is a Southwest native for the partly shaded bed medium to low water-use bed. It's a butterfly magnet, particularly for the Monarch butterfly which passes through about the same time the mist flower is bloom in late summer into fall. Masses of lavender blue flowers top the plant for which it gets it names, am appearance of blue mist. Frequently, butterflies will be seen topping the flowers. Gregg's mist flowers will spread by roots, allow it some room.
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.
Cliff fendlerbush is another Texas and Southwest native shrub too little used in the xeric landscape. Springtime lifts the cliff fendlerbush above the ordinary into prominence in the landscape. It is said the ravines and arroyos look dotted with snow from a distance, so profuse are the fragrant, creamy white, sometimes with a pink tinge, four petaled flowers in May and June. It's natural element is rocky arroyos (rupicola=rock dweller), cliff ledges and limestone soils with good drainage that average 12-18 inches of moisture with hot sunny days.
Snowberry is a woody plant that spreads from the roots, sending up arching branches every couple of inches to about 3-4 feet high. The small green leaves are pleasant as are the white spring flowers, followed by the remarkable pearly white berries. During the summer, I inspect the snowberry bush weekly for signs of the berries. They never remain long on the bush, as the birds quickly devour them (they're said to be toxic to humans). Snowberries thrive in part shade and medium to low/medium watering. they easily propagate by digging out and transplanting the roots.