USDA Hardiness Zone 6

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

Other Cold Hardiness categories

Common Name: Coral Canyon Twinspur

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.

Common Name: English Lavender 'Munstead'

Outstanding shrubby perennial fragrant herb for the garden! Very good soil drainage is the key to growing lavender, it does not like moist, compacted clay soil. Lavender appreciates supplemental irrigation every 2-4 weeks, if not provided naturally. Trim back in late winter or early spring by not more than a third, or just trim down last years flower stems. Triming too much off the plant will kill it.

Common Name: Mersea Yellow Pineleaf Penstemon

‘Mersea Yellow’ is similar to the orange red pineleaf penstemon in culture, except for requiring a bit more water. Native perennial to the Southwest. Its leaves are lighter green, but still evergreen, without the tinge of mahogany in winter. ‘Mersea Yellow’ is an excellent selection for the medium water-use zones of your landscape. One of the few yellow flowering penstemons.

Common Name: Silver Speedwell

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.

Common Name: Prairie Sun Black-eyed Susan

Rudbeckia is advertised as heat and drought tolerant, but I have not found it so. I’ve found it to require at least weekly watering during the heat of the summer. A shortlived, southern native perennial, it likes the humidity and rain from southern climes. These very large and stunning composites may be worth your effort, just place within the correct hydrozone.

Common Name: Gro-Low Sumac

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.

Common Name: Bee Balm

An American native requiring medium to high water, it is a prolific grower, an old fashion pass-along plant. Perfect for a mixed border or at the edge of the vegetable garden to attract bees. The variety shown is most likely 'Violet Queen', although I'm unsure. However, it is not the common scarlet bee balm or red bergamot, that also grows well here. Blooms throught the summer and is an attractive addition.

Common Name: Virginia Creeper Vine

Virginia creeper, one of our pernicious native creepers, is a worthy low care vine for brilliant fall foliage and deep blue berries (highly toxic to humans) loved by birds. Virginia creeper normally spread by seeds in bird droppings, which is the method it came to my landscape. When spotted early, Virginia creeper easily pulls out, but if not spotted, within no time, it will cover a fence, climb a pole or cover an area. Which can be either a good thing or a bad thing, depending on one's view.

Common Name: Utah Serviceberry

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.

Common Name: Western Sand Cherry

Western sand cherry is a shrub native to the northern plains favoring sandy soils. Cold and heat tolerant, and low water-use once established. Beautiful, fragrant white flowers in spring time, producing edible black cherries (however, some references advice not to eat the fruit if it is bitter).

Common Name: Columbine, Golden or Yellow Columbine

Delicate and fragile in appearance, columbines are some of the most durable, versatile plants in the West. Aquilegia chrysantha is the Texas native columbine, happy in both sun or shade, moist areas or dry. Aquilegia chrysantha is native to the Chihuahuan and Sonoran Desert canyons from west Texas, southern New Mexico, southern Utah, and Arizona south into Sonora, Coahuila, and Nuevo Leon along with a disconnected population in southern Colorado.

Common Name: New Mexican Agastache

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.

Common Name: Purple Coneflower

A terrific variety for the prairie garden, though requiring prairie conditions -- good soil with good drainage and more frequent watering than our native, E. angustifolia. Coneflowers are all the rage right now with many new introductions every year, ranging from white, yellow, orange to the popular purple. Most of these should be located in your medium to high water-use area. The richer the soil and with weekly watering (high), you'll enjoy grander blooms. A good border plant in the transition area between turf and medium water-use. E.

Common Name: Silver-edged Horehound

The only draw back to this pretty, silver-edged groundcover is its flowers! If only it didn’t, it would be a perfect no maintenance, no water groundcover for hot, sunny locations. You can see the tiny ball shaped flower heads in the picture, which look rather indistinct. However, after flowering, they turn an ugly shade of brown that mar the beautiful leaves unless you shear them off. Though a creeping groundcover, silver-edged horehound is not invasive like the common horehound, M. vulgare.

Common Name: Russian Sage

Russian sage is a must have shrub for every low water-use landscape. Russian sage is used extensively throughout our southwest landscapes, planted along with Buddleia, Carl Forester Reed Grass, Salvia greggii cultivars, Anisacanthus quadrifidis wrightii and Hesperaloe parviflora. It is hard to beat its use where a long flowering, showy, low care, drought tolerant shrub is needed.

Common Name: Color Guard Yucca

There are numerous interesting yuccas to choose from besides the Yucca glauca or Y. angustifolia seen throughout our area. Y. filamentosa ‘Color Guard’ has some of the most striking variegation and will even flower in part shade, cold hardy to Zone 5. Other Y. filamentosa varieties to consider growing in our area are ‘Bright Edge’ and ‘Golden Sword’.

Common Name: Goldenrod 'Wichita Mountains'

This variety purchased from Sunshine Nursery in  Clinton, Oklahoma is drought tolerant, I've planted it in a low water-use bed. The flowers are so dense and golden, it looks like a golden torch. Sometimes seen as Solidago speciosa rigidiuscula, 'Wichita Mountains'

Common Name: Blue Mist Spirea

Rarely does a shrub feature as much versatility as the blue mist spirea. It will grow and flower in sun or shade, low water-use or high. This Caryopteris, a hybrid itself, normally blooms in a pleasant light blue, but other selections have deeper blues hues. Summer blooming into fall. And as unlikely at it seems for hybrid to set viable seed, blue mist spirea reproduces itself pleasantly, never invasively. Indeed, any little volunteers are welcome.

Common Name: Sunflowers

One of North America's favorite annuals. There is much variety in size and colors of flowers, ranging from yellow, golden, orange, red/orange, red and mahogany. The plants themselves can vary from 3-4 feet to 8 feet or more. Seeds sown in springtime will be insure blooms in late summer or fall. Great for cut flowers.

Common Name: Maypop, Passion Vine

Maypop, or passion vine, is a perennial vine native to eastern and southern areas of the U.S. In the South, maypop grows into a woody vine, but in northern areas like the Texas Panhandle, it will die back to the ground. Lobed, dark green leaves, beautiful, unique flowers emerge in the summer to fall, producing edible fruit. Maypop will sucker, especially when ample watering is present. Passion vine, the most cold hardy of the genus, should be cold hardy to Zone 6.

Common Name: Narrowleaf Mountain Mahogany, Littleleaf Mountain Mahogany

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.

Common Name: Gambel Oak

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.

Common Name: Buckwheat, Golden Sulfur-flower

Golden sulfur buckwheat is one of those plants you'll come across while hiking in the West and wonder why it isn't in your garden, its so adorable!
The leaves are gray-green, spatula shaped and woolly underneath, to about 2-3 inches. They form a rosette at the base. In early spring, tall, stout stems extend upward up to 2-3 feet. The bright golden flowers are nearly luminescent, appearing first as ball-like umbels (clusters), then each ball opening up to a circle of golden flowers. As the flowers age, then turn orange.

Common Name: Hollyhock

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.

Common Name: White Swan Purple Coneflower

A beautiful white variety of the purple coneflower. This picture doesn't do the flower justice.

Similar to the purple coneflower, this white variety is really a high water-use plant that appreciates afternoon shade. Deadhead to prolong the bloom period, but keep end of season blooms on for fall and winter interest.

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