The term "succulents" often evokes images of thick, fleshy-leaved ground covers and warm desert landscapes, but this diverse, water-wise group is full of surprises. True succulents temporarily store water in their roots, stems or leaves. In times of need, they draw on that supply and sail through dry weather. Many succulents also flourish in extreme low temperatures by lowering their water reserves. Cold-hardy succulents all require abundant sun and fast-draining soil, especially during winter months.
Stonecrops (Sedum spp.) are cornerstones of cold-climate gardens, adding colorful plump foliage and vibrant late-season blooms. Many upright varieties, such as the deep maroon "Black Beauty" stonecrop (Sedum "Black Beauty"), routinely withstand winters in U.S. Department of Agriculture plant hardiness zones 3 through 9. Tiny ground cover stonecrops scoff at winter's depths. Spanish stonecrop (Sedum hispanicum) and dwarf Spanish stonecrop (Sedum hispanicum var. minus) form mats of thick, button-like evergreen foliage that intensifies with shades of blue, green and red as temperatures fall and rise. These diminutive beauties are hardy in USDA zones 2 through 9, withstanding extreme winter temperatures of 50 degrees below zero Fahrenheit.
Cold-climate gardeners know the resilience of hens and chicks (Sempervivum spp.). Also known as houseleeks, the seemingly indestructible plants live up to their Latin name "ever-living." Rosettes of fleshy leaves send up thick-stemmed, colorful blooms. The parent plant dies, but life continues as the crowded "chicks" carry on. Whatever your color preference -- greens, blues, reds, purples -- cold-hardy sempervivums exist. Cobweb houseleek (Sempervivum arachnoideum), hardy in USDA zones 3 through 10, adds a fine-fibered web to gray-green rosettes. "Krebs" desert rose hens and chicks (Sempervivum "Krebs"), hardy in USDA zones 4 through 9, withstands temperatures of minus 30 degrees. Its evergreen rosettes meld blue, green, silver and pink.
Unlike the invasive, warm-climate ice plant (Carpobrotus edulis), hardy in USDA zone 8 through 11, cold-hardy ice plants (Delosperma spp.) bring their silvery, succulent foliage and brilliant flowers to cold-climate gardens and high elevations. Mesa Verde ice plant (Delosperma "Kelaidis") tops a mass of frosty succulent leaves with salmon pink flowers. "Fire Wonder" ice plant (Delosperma "Fire Wonder") adds oversize reddish-orange-and-yellow blooms. Both survive winters in USDA zones 4 through 10. Cooper's hardy ice plant (Delosperma cooperi) withstands lows from USDA zones 5 through 11. Though it draws the line at 20 degrees below zero, Cooper's ice plant wins praise for its non-invasive adaptability and brilliant magenta blooms.
No list of cold-hardy succulents is complete without at least one cactus. Cactuses are succulents, but they don't store water in their leaves. Their modified leaves, also known as spines, fend off intruders instead. Cactuses store water in their succulent stems. The reigning king among cold-hardy cactuses is brittle prickly pear (Opuntia fragilis), the northernmost cactus species in the world. From near the Arctic Circle all the way through Texas, it withstands temperatures from 58 degrees below zero to 131 degrees above zero, spanning USDA zones 1 through 13. It rapidly lowers its water content when bitter cold comes, but bounces back with abundant pink and yellow blooms. Several cold-hardy cactuses thrive where winters regularly register 20 to 25 degrees below zero.