Succulents are plants uniquely adapted to store water in their fleshy leaves, stems, or roots, and are often associated with warm, arid climates. Whether these plants can survive snow and freezing temperatures depends entirely on the specific species and the severity of the cold event. While snow can sometimes act as a temporary insulator, the freezing temperatures pose a significant threat to most succulents. Survival is determined by a plant’s inherent tolerance to cold, known as cold hardiness.
Understanding Cold Hardiness
Succulents are broadly categorized into two groups based on their ability to withstand low temperatures: tender and hardy varieties. Tender, or “soft,” succulents originate from tropical or subtropical regions where frost is virtually unknown. They possess little tolerance for freezing conditions, suffering damage when temperatures drop below 32°F (0°C). These types include popular houseplants like Crassula (Jade Plants), Echeveria, and Aeonium.
Hardy succulents are native to temperate or mountainous environments and can survive significant periods below freezing, often down to -20°F. They achieve this by going dormant and accumulating cryoprotectants, natural compounds that help prevent freezing inside the cells. Well-known examples include most species of Sempervivum (Hens and Chicks) and many Sedum (Stonecrop) varieties. These hardy types are often better off remaining outdoors in winter, as moving them inside can disrupt their natural cold-acclimation cycle.
The Mechanism of Freezing Damage
The danger of freezing to tender succulents lies in the large volume of water stored in their tissue. When temperatures drop below freezing, water outside the plant cells freezes first, forming ice crystals in the extracellular spaces. This process causes water stored inside the cells to move outward to equalize the pressure gradient.
This outward movement causes severe cellular dehydration, damaging the delicate cell membranes and leading to cell death. This is known as “freeze-thaw” damage, where rapid desiccation or the expansion of water inside the cells causes the cell walls to rupture. The visible result of this cellular collapse is tissue that appears translucent, mushy, or blackened. Furthermore, excess moisture from melting snow or ice promotes fungal diseases and root rot once the plant is compromised.
Preparing Succulents for Winter
Preventative action is the most effective way to ensure the survival of non-hardy succulents during the winter months. The primary step for potted, tender varieties is to bring them indoors before the first expected frost, ideally when nighttime temperatures consistently fall below 50°F. Placing them near a south or west-facing window helps them receive maximum sunlight during their winter dormancy.
For all succulents, reducing watering frequency during the fall and winter is necessary, typically to once every three to four weeks, allowing the soil to dry completely. A dry plant is more cold-tolerant than a water-saturated one, as less water is available to freeze and damage the tissue. For borderline-hardy plants remaining outside, temporary protection can be provided by covering them with a frost cloth, burlap, or a blanket overnight when frost is predicted. This covering should be removed in the morning to prevent overheating.
Assessing and Treating Frost Damage
Following a frost or snow event, patience is required, as the full extent of the damage is not immediately clear. Do not move or touch the plant while it is still frozen, as this worsens damage to the fragile, ice-laden cells. Wait until temperatures have risen and allow 24 to 48 hours for the plant to acclimate and for the damaged tissue to clearly define itself.
Frost-damaged tissue will appear dark, mushy, or translucent, signifying the irreparable collapse of the cells. Once the full damage is apparent, use a sharp, sterilized cutting tool to prune away all compromised parts. Cut slightly into the healthy, green tissue to ensure all rot is removed. The tool should be sterilized with alcohol between cuts to prevent spreading pathogens. The remaining healthy plant should then be kept dry in bright, indirect light to encourage healing and new growth.