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.
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.
Old fashion garden and English cottage garden herbaceous perennial that works well in the Southwest Cottage Garden. Hollyhocks are considered to be either a biennial or perennial. They produce copious seed but are not considered invasive or troublesome. Plant seed in the fall, or early spring. Avoid watering the foliage if irrigating, a drip system works better that above ground sprinklers.
Elephand ears are plants grown from corms (called bulbs, but not true bulbs), with large leaves on upright stems. Colocasia leaves point downward (Alocasia leaves point upward). Colocasia gigantum and C. esculenta are two species most often used. These plants are grown primarily for their foliage and prominant veining, rather than flowers. The flowers are typical aroid type with a white to yellow or light green spathe, and may not even flower in shorter growing seasons.
Rose of Sharon, or Althea, is another reliable old-fashioned garden plant well suited for the Texas Panhandle. My favorite cultivar is Diana because of the brilliant, pure white 4-5” flowers and somewhat glossy green leaves. Diana is also one of the smaller varieties up to about 6 - 8 feet, while others can reach 10’ tall. Similar to most altheas, 'Diana' is a prolific bloomer.
Exciting perennial ornamental oregano for your low water-use or Mediterranean style garden. Spreads slowly by rhizomes and is easily propagated by root cuttings in fall or early spring. The flowers elongate as the summer progresses, eventually drying to a papery brown by summers end. In a wet fall, some new flowers may still appear. O. libanoticum is best placed to drape over a rock to showcase it’s drooping nature.
1997 Perennial Plant of the Year was chosen for it versatility in growing in many different regions of the US. And it will grow in our Panhandle gardens as well. Although reported to be drought tolerant once established, it does much better in a medium water-use environment with afternoon shade. When it is excessively hot and dry, it suffers from stress, but usually survive. Just give it a little more water when this happens.
Attractive to bees and butterflies. Seedlings may happily appear in springtime. Native to Europe and Central Asia.
Low growing, drought tolerant evergreen groundcover that becomes covered in tiny sky blue flowers in early spring for about 6 weeks, then sporadically throughout the year. I’ve seen a few twinkling blue blooms in every month of the year. The tiny leaves of V. pectinata are gray-green and tomentose. Allow plenty of room for the spread of this fabulous groundcover; it’ll just keep going and going and going. And you won’t want it to stop.
Most notable in the meadows and fields of California, the California poppy grows throughout the southwest. Considered to be both annual and perennial, it either comes back the next year or it reseeds. Once you have a stand established, it should continue in your landscape, but not invasively so. This past summer of 2012, my California poppies bloomed in both the spring and our unusual fall. Blooms in April and May. Finely cut blue-green foliage make an attract plant outside the bloom period. The foliage should die back in summer.
Santa Fe phlox is rarely available even at native plant nurseries, but when it is, don't pass it up. Sun loving and drought tolerant, the Santa Fe phlox blooms late spring throughout the summer with once a month watering. Five petaled, small pink flowers about an inch across with a small white eye can cover the plant. Native to canyons, mesas, and rocky desert slopes from West Texas to southeastern Arizona and into northern Mexico. Seeds of the phlox pop out when they are mature, making seed collection and propagation difficult.
Broom snakeweed is a small mounded subshrub with yellow greenish thread-like leaves, native throughout the Southwest and western half of the North American continent. In the fall, it becomes covered in small golden yellow flowers. Bees and nectar butterflies are attracted to it in numbers. Usually grows to only a foot tall.
White flowering zinnia is native to the Southwest and Northern Mexico. A low mounding plant, it becomes completely covered with small white flowers with a central yellow disk, similar to our native prairie zinnia, Zinnia grandiflora. Blooms from June through fall. Desert zinnia is toxic if ingested by humans.
New Mexican privet can be viewed either as a tall shrub or smaller tree. New Mexican privet will flower (tiny yellow) before leafing out with small oval glossy green leaves to be followed with black berries in the fall. Heat and drought tolerant will live in most soils and water-use areas. Attractive taller plant for the home landscape, similar to the yaupon holly in form.
The vitex, or chaste tree is a small tree or a very large shrub, depending on water and climate, and is cold hardy to the Texas Panhandle. Low water-use once established, it can grow well in higher water zones. It is called the summer lilac because of the similarities of its flowers to the lilac shrub. Vitex varieties can be found in blue, lavender, and pink fragrant flowers. The leaves are similar to those of the marijuana plant. Vitex will sucker, especially when given ample water. It is native to southern Europe and Western Asia.