USDA Hardiness Zone 6

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

Other Cold Hardiness categories

Common Name: Columbine

Many Aquilegia’s are native to the U.S. Golden columbine, Aquilegia chrysantha is a Texas and southwest native, has yellow flowers and can take more sun than some varieties. McKana's Giant is the hybrid columbine most often sold. Large beautiful bi-colored flowers dazzle in woodland and shady area. Rocky Mountain columbine, Aquelegia caerulea; and wild columbine, A. canadensis, are other common columbines. Rocky Mountain columbine is the state flower of Colorado.

Common Name: Larkspur

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.

Common Name: Bearded Iris, Hybrid Cultivars

Distinctive flat, thin upright leaves with flowers arising from the stem.

Common Name: Red Rocks Penstemon, Red Rocks beardstongue

‘Red Rocks’ is another hybrid cultivar, named for the Denver, Colorado red sandstone area and amphitheater. P. 'Red Rocks' is highly suitable for the average garden, rather than a specialized penstemon bed. Again, do not deadhead unless reblooming has occurred and you desire a tidier appearance. Don’t over water or over amend the soil, but it will thrive companionably with other medium water-use plants.

Common Name: White Bouquet Tansy, Silver Tansy

A non-invasive tansy from southern and central Europe for your low water-use bed and border that will reseed somewhat. A short lived perennial. Gray cut-leaf foliage provides an attractive white element in the garden.

Strongly aromatic.

Common Name: Prairie zinnia, plains zinnia, desert zinnia, mountain zinnia

Not our old fashioned garden zinnia.  Zinnia grandiflora is the native zinnia for most of the Midwest, West and Southwestern parts of the United States. So widespread a wildflower, each region has named it theirs: plains zinnia, prairie zinnia, desert zinnia and Rocky Mountain zinnia. A terrific low growing and spreading groundcover for poor soils needing no supplement irrigation. Rugged! A survivor without being a pest!

Common Name: Scarlet globemallow

Scarlet globemallow is a welcome addition to any xeric or High Desert garden. Small coral flowers bloom from May (sometimes April) through into the fall. Although scarlet globemallow will survive with no additional moisture in our climate, once a month watering insures steady blooms. The plant is similar in appearance to S. ambigua, which can bloom coral, white, lavender and pink.

Common Name: Century Plant, Agave

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.

Common Name: Tansy Aster, Tahoka Daisy

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.

Common Name: Giant Sacaton

Giant sacaton is one of the largest bunch grasses native to the Southwest, like alkali sacaton on steroids. Seems to thrive in poor soils with no supplemental irrigation. It will grow even bigger with added moisture. Thick textured grass blades, it will rival pampas grass for size and beauty, although it plumes are near as showy, giant sacaton has a flowing fountain appearance. A warm season grass, it is cold hardy and thrives in sun and heat.

Common Name: Beargrass, Sacahuista

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.

Common Name: Hyacinths

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.

Common Name: Bear's Breeches

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.

Common Name: Yellow Corydalis

Delicate fern like foliage for your shaded woodland areas. Will grow in a low water-use zone, however, the foliage will disappear in summer. Delicate tubular, yellow. White and blue varieties have been available locally. An excellent choice for underplanting trees, especially for a medium water-use zone.  Will reseed.

Common Name: Crape Myrtle

Grown in the South for decades, most people think of crape myrtle as a native American plant; it is however native to China and Japan. Small tree or large shrub that is cold hardy to Zone 7.  I’ve grown the same crape myrtles for over 20 years, but they’re planted close (too close!) to my bricked house on both the northeast and northwest corners. They’ve been stem hardy, not just root hardy, and have grown up to about 10-12’. In most cases, crape myrtle will not grow into tree form in the Panhandle, but there are mature, tree size crape myrtles in Amarillo.

Common Name: Pineleaf Penstemon

A long-lived evergreen penstemon for the average bed or border. Small orange red tubular flowers attract hummingbirds, as do most red tubular flowers. Low growing and longer flowering than most, especially the more mature the specimen.

After several years, the pine needle like foliage can resemble a miniature bonsai. Pineleaf penstemon is also a must-have for the low water-use bed or border or rock garden because of its evergreen foliage and longer blooming nature. In late summer, snip off the dried, spent flower heads; some re-blooming may occur.

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: Black and Blue Sage, Anise scented sage

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.

Common Name: Desert globemallow

Desert globemallow is one of those native plants that keeps on giving, asking so little in return and is a worthy addition to any native or xeric garden. Typically, desert globemallow sports pretty pink flowers. though some plants will bloom white, coral or lavender. Whatever color, they are worth the addition to your sunny and dry landscape for their pleasant cheery nature. Similar to appearane to S. coccinea, a coral blooming species.

Common Name: Cactus

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.

Common Name: Bigelow's Tansyaster

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.

Common Name: Prairie Dropseed

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.

Common Name: Littleleaf Mockoragne

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.

Common Name: Coral Bells, H. sanguinea, Alum root

Common Name: Greek yarrow

Small green gray evergreen leaves forms mounded, low growing xeric plant with small white flowers in late spring. Does not spread vigorously. Easily propagated by root cuttings. An alpine from the Balkans region.

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