Soil that contains a high percentage of fine particles smaller than .002mm in diameter and colloidal substance and becomes sticky when wet. Clay soils can be mixtures of clay, sand and silt, with clay having the greatest percentage.
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.
Tansy aster is an annual native to the Southwest and throughout the Plains even into Canada. Fernlike, or tansy-like (tannacetifolia) light green foliage with beautiful aster-like lavender flowers with yellow disks about 1 1/2 to 2 inches across. Blooms from late spring through fall. A once a month watering will keep the blooms coming throughout the summer. It will keep its compact shape in lean, poor soil but will become much larger in well amended soil. Minimal amending is recommended. Tansy aster is another example of our natives plants giving so much, asking so little in return.
Prairie dropseed is smaller than both alkali or giant sacaton, more fitting for the city garden. A warm season bunch grass, prairie dropseed is a most attractive low or medium water-use grass with graceful green foliage. The seed heads emerge in late summer into fall with light pink seeds, that is said to naturalize some, but not invasively. A slow grower. Foliage turns a pleasing golden orange in the fall. Native throughout the Great Plains, including Texas. Tolerates most soil conditions.
Bear grass is similar in appearance to yucca and clumping grass, but is neither. Usually found growing in high desert areas, along cliffs and rocky slopes. Thin succulent grasslike yellow-green leaves emerge from a trunkless center, are pointed and sharp edged. A plume-like inflorescence with many tiny cream colored flowers emerges early summer. Cold hardy, drought and heat tolerant.
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.
The old fashioned larkspur is a drought tolerant reseeding annual, previously associated with delphiniums (now in the Ranunculaceae family). I’ve grown it in my alley, in the xeristrip, and its crept into my medium water-use zone. Deadheading keeps millions of tiny seeds from overcoming your garden next year, and also keeps the blooms coming. Larkspur can flower for six weeks. Again, deadheading is important to prevent a massive infestation throughout your landscape.
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.
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.
Sedum, ‘Autumn Joy’ is one of those foolproof additions to your autumn garden, so aptly named; for the joy it brings to the autumn garden. Easily propagated by stem cuttings or root division. As with most sedums, afternoon shade helps. Grasshoppers have nibbled at its leaves in early summer without stunting the plant’s flowering ability.
Desert marigolds are one of the prettiest desert flowers. The plant forms a neat compact rosette of finely cut silvery green leaves from which stems emerge topped with a bright golden daisy like flower. It is considered either an annual or short lived perennial. Scatter seeds from the spent plant to insure its return the next season. Over watering will doom this beautiful plant. Desert marigold can be seen blooming in the desert in winter and spring. In my garden, it's blooms begin in May and will continue sporadically into fall. Not awfully reliable in cold hardiness here.
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.
Bigelow's tansyaster is easy to confuse with Tahoka daisy but is not as showy. Bigelow's aster is a fall blooming biennial, with far fewer purple rays and a smaller, yellow brown center disk. It populates plains in Colorado, Arizona and New Mexico. In the fall, whole fields will wear a purple haze due to this tansyaster.
Utah serviceberry is a quite beautiful shrub extending from the Southwestern states northward throughout the Rocky Mountains and through various ecosystems between 4000 and 8000 ft in elevation. Deep green leaves, large oval shaped and toothed at the margins, many intricately branched, smooth gray to maroon bark. Large white flowers with five widely spaced petals open in May and June. Berries appear in the summer, ripening to pink, then red, then finally dark blue. Leaves turn red and orange in the fall.
Littleleaf mockorange is native throughout the foothills, dry rocky slopes and open woodlands from 4000 to 8000' in the Southwest usually growing to only 4 feet. This native mockorange is similar in form to the European import, they are fragrant, but not of orange. Attractive white, 4 petaled flowers bloom in early summer, small slightly glossy green leaves. Coldy hardy, heat and drought tolerant.
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.
Perennial from South Africa noted to be cold hardy for our area, but I’ve had mixed results, most years it didn’t winter over (although reported to be Zone 5). However, it will flower nicely the first year in the garden, so I’ve kept trying it. A Plant Select Plant for 2000. Perhaps it needs moister conditions in the winter than what I give it.
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.
Yuccas for Texas High Plains Landscapes
Verbascums make a presence in the wildflower or cottage garden and mixed border, whether it be this common mullein, or another species with showier flowers. Verbascums can be either biennial or perennial, but will make enough seeds you’ll never be without. Some are drought tolerant and thrive in poor, but well drained soil, others may need medium water use and a richer soil.
Sumacs are known for brillian fall foliage. Ground cover woody shrub 24-30" tall with dark shiny green leaves that turn a thrilling orange-red in the fall. Small yellow flowers at springtime.
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.
Rounded mounds of green leaves on multi-forked stems put forth multitudes of fragrant purple/magenta flowers from summer into autumn. Flowers open in late afternoon (perhaps around four o'clock) and close in early morning. Cold hardy and heat and drought tolerant, after freezing in the fall, the top growth breaks away. Desert four o'clock emerges in the spring from a large root. Will not transplant well once established. Southwest native perennial is usually found in somewhat shaded areas.
Littleleaf mountain mahogany is the shortest of the mountain mahoganies usually sold. Small, narrow, leathery looking evergreen leaves on many intricate branches. Small yellow flowers in springtime and feathery seed plumes in the fall. The shrub is densely branched and slow growing.
Gambrel oak is a common native oak species throughout the Rocky Mountain foothills and here in the Texas Panhandle as well. Often times it grows more to a tall shrub, with sufficient moisture it can mature into a small tree. Beautiful somewhat glossy lobed green leaves to 3-5 inches long. Beautiful fall foliage. Will put out a profuse amount of acorns. Gambrel oak can form a thicket. Cold, heat and drought tolerant. Inconspicous tiny red flowers appear shortly after leafing and are normally hid by the leaves.
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.