USDA Hardiness Zone 6

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

Other Cold Hardiness categories

Common Name: Sweet Autumn Clematis

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.

Common Name: Red pincushion flower

Perennial with lyre shaped leaves, similar in appearance to scabiosa, native to central Europe. In fact, it's synonym is Scabiosa rumelica. Deep purple red pincushion-like flowers. Knautia macedonica may suffer from our alkaline soil if not well amended with compost and well drained. Will reseed some. Has a pleasant wild look. Popular with nectar feeding insects. Deadheading doesn’t seem to be necessary.

Common Name: Cascading Ornamental Oregano, Lebanese Oregano, Hop Oregano

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.

Common Name: Prairie Skullcap

Our native skullcap is one that should be included in every drought tolerant landscape, short lived though it is. This is the kind of garden-worthy plant we all desire, neat, compact and all season blooming with no maintenance to speak of. You just can't go wrong as long as your soil has decent drainage. It reseeds some, but to me, this is just a bonus.

Common Name: Frosty Morn Sedum

The Crassulaceae family of plants fascinates me, and the sedums are one of its larger genera. I first saw ‘Frosty Morn” featured on a gardening program from Iowa, so I wondered whether it’d be drought tolerant. Shortly afterwards, I found it at our local nursery and planted in my xeristrip. It has never faltered. The only disfiguring occurrence is a little nipping by grasshoppers during early summer, which has never seemed to harm it, or other large leafed sedums.

Common Name: Stansbury cliffrose

Previously known as Cowenia mexicana, it is known today as Purshia stansburyana, also, P. stansburyiana. It is still commonly called a cliffrose. The cliffrose blooms prolifically in May with creamy white to pale yellow fragrant flowers that continue blooming for several weeks. Semi evergreen, it loses it's leaves in colder winters. Upright stems and branches can appear unruly in its growth pattern; small dark green resinous leaves.

Common Name: Big Bend Silverleaf

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.

Common Name: Honeysuckle, coral

Another American native vine, evergreen in more southern climates than ours, but cold hardy here. Fragrant and attractive coral flowers in spring and early summer. Attracts birds, butterflies and hummingbirds. Pleasant glossy green leaves. Not invasive. Medium water-use.

Common Name: Alkali sacaton

Alkali sacaton is a perennial warm season bunch grass native to the Southwest. In late summer to fall, airy triangular seed heads wave above the silver green grass blades. Grows in alkali soils, many say in locations where there is moisture nearby, prefering heavy clay soils. It is quite drought tolerant once established, and long lived. It will, of course, grow bigger or smaller depending on water resources.

Common Name: Green Santolina

Green santolina is an evergreen shrub native to the Mediterranean region. Its grass-green color makes it a welcome addition to any landscape. Medium and low water use, cold hardy, sun and heat tolerant, it prefers poorer soil. Aromatic green leaves that resemble those of the cypress. Yellow button flowers in summer.

Common Name: Mat Daisy, Atlas Daisy

Mat daisy is a low growing spring blooming plant. Drought tolerant. Not exactly a groundcover, as the top growth disappears during summer and reemerges as a green basal rosette in fall, getting ready to bloom again in the spring. Blooms late March to May with small white daisy-like flowers that have pink undersides. Forms a compact ground-hugging mat. Will self seed some, but never invasively.

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: Stonecrop

There are many different sedum species and varieties of this delightful spreading groundcover. I took this picture on a garden tour in Angel Fire New Mexico, and have not been able to identify it yet. It is easy to see from the picture how it got its common name, stonecrop. Sedum groundcovers spread nicely in a low to medium water use area of gritty, well drained soil, and will do just fine in afternoon shade.

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: Mohave Sage

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.

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.

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