Which Succulents Are Cold-Hardy?

Succulents add interest to any garden because of their variety of unusual shapes, colors, textures and sizes. Drought-hardy by nature, succulents can be adapted to containers, ground covers and rock gardens. Some succulents must be protected from freezing temperatures; these are referred to as tender or soft succulents. However, there are a number of species that tolerate freezing temperatures, some as low as minus 40 degrees Fahrenheit , which corresponds to U.S. Department of Agriculture plant hardiness zone 3.

Succulents are plants with thickened, fleshy leaves and stems for storing water. Botanically, cacti are considered succulents; however, gardeners and horticulturists generally do not include cactus in that definition. Succulents have adapted to dry, semi-desert climates all over the world, such as high mountains, dry tropics and temperate coasts. They typically have shallow roots that allow them to quickly absorb water after a light rain. The plant uses the stored water during the dry season. Hardy varieties include hens and chicks (Sempervivum spp.), stonecrops (Sedum spp.), ice plants (Delosperma spp.) agaves (Agave spp.) and yuccas (Yucca spp.).

Sempervivum means "live forever" – a testament to its hardiness. It is also popularly referred to as hens and chicks because it usually grows in low mounds with young plants or "chicks" sprouting up around the perimeter. Each plant is rosette-shaped with shadings of reds, pinks and greens depending on the species. The chicks can be cut and used to start new plants: Cut the stem to 1 inch, place the plant in shade for two days, then plant and water. Cold-hardy varieties include: "Green Wheel" hens and chicks (Sempervivum "Green Wheel"; USDA zones 4 through 9); cobweb houseleek (Sempervivum arachnoideum; USDA zones 3 through 10) and "Black" hens and chicks (Sempervivum "Black"; USDA zones 4 through 9).

With more than 600 species, sedums or stonecrops have a number of growth habits from low-spreading plants for ground cover to upright plants with spikes of pink flowers suitable for cutting. Masses of low-growing sedum are sometimes used as living roofs to provide buildings with insulation from the sun. There are a large number of cold-hardy sedums, which include: "Autumn Fire" (Sedum "Autumn Fire"; USDA zones 3 through 9); Corsicum (Sedum corsicum; USDA zone 4) and Grisbachii (Sedum grisbachii; USDA zone 4).

Delosperma, commonly known as or ice plant, is readily seen along the California coast where it has a low growth habit and forms extensive mats with flowers of white, pink or yellow in spring and summer. The cold-hardy varieties of iceplant have a more restrained growth pattern and form smaller mats, but the masses of aster-like flowers have the same lively colors as the coastal versions. Cold-hardy ice plants include: Mesa Verde (Delosperma Mesa Verde; USDA zones 5 through 7); "Jewel of the Desert Moonstone" (Delosperma cooperi "Jewel of the Desert Moonstone"; USDA zones 5 through 10) and hardy yellow (Delosperma nubigunum; USDA zones 4 through 7).

Agaves and yuccas are larger, upright succulents with a painfully sharp point on their leaves. Both grow singly or in groups and produce flowers on tall spikes in the spring. Examples of cold-hardy agaves are New Mexico century plant (Agave parryi var. neomexicana; USDA zones 5 through 10) and Harvard’s century plant (Agave havardiana: USDA zones 5 through 10). Examples of yuccas are blue beaked yucca (Yucca rostrata; USDA zones 5 through 10) and golden sword yucca (Yucca filamentosa "Golden Sword"; USDA zones 4 through 9).