Succulents, with their striking forms and ability to store water, have become popular plants. These desert-adapted species are prized for their low maintenance needs and drought tolerance. Whether these fleshy plants can endure the cold of winter outside depends entirely on the plant’s specific genetics and the local climate conditions it faces. Understanding the difference between plant types and your environment is necessary to successfully keep succulents outdoors year-round.
The Role of Hardiness Zones and Temperature
The ability of any plant to survive winter is determined by the climate where it is grown. The United States Department of Agriculture (USDA) Hardiness Zone system is a standardized map that divides North America into zones based on the long-term average annual extreme minimum winter temperature. Knowing your zone is a fundamental step in deciding if a succulent can remain outside.
The critical temperature for most non-hardy succulents is freezing, or 32°F (0°C). When the water stored in their leaves and stems freezes, it expands, causing the plant’s cell walls to rupture and resulting in irreparable damage. Many “soft” succulents begin to show signs of stress, such as discoloration, when temperatures consistently drop below 40°F (4°C). Prolonged exposure below this threshold, especially when combined with moisture, will likely lead to plant death.
Identifying Succulent Types That Survive Winter
Succulent species are broadly categorized into two groups based on their cold tolerance: hardy and soft (tender) varieties. Hardy succulents originate from regions that naturally experience freezing temperatures and have developed mechanisms to survive the cold. Many of these can withstand temperatures as low as -20°F (-29°C), placing them in USDA Zones 5 or 4.
The most reliable hardy genera include Sempervivum (Hens and Chicks) and many species of Sedum (Stonecrop). These plants often enter a state of dormancy during winter, sometimes changing color or losing leaves, and they require a period of cold to thrive long-term. Some varieties of Orostachys are also known for their impressive cold tolerance, surviving well into sub-freezing conditions.
Conversely, soft succulents are native to warmer climates where frost is rare or non-existent. These plants, which include the popular Echeveria, Crassula (Jade Plant), Kalanchoe, and most Cacti, are extremely susceptible to freeze damage. If you live in a region with any risk of frost, these tender varieties must be brought indoors or provided with substantial protection to survive the season.
How to Prepare Outdoor Succulents for Cold Weather
For hardy succulents or those in borderline zones, preparing the plants for winter involves managing moisture. Excellent drainage is paramount for survival, as cold, wet soil leads to rot and freezing. Ensuring the planting bed or container uses a gritty, well-aerated soil mix prevents water from pooling around the roots.
Watering should be significantly reduced or eliminated entirely starting in late fall, as most hardy succulents enter a dormant phase. Keeping the soil relatively dry throughout the cold months helps the plant concentrate its internal compounds and resist freezing. If heavy winter rains are expected, temporary overhead protection, such as a clear plastic sheet or a cloche, can be used to keep the soil from becoming waterlogged.
Physical protection can provide a significant temperature buffer, especially during brief cold snaps. Positioning plants against a south-facing wall or under the eaves of a house creates a microclimate that retains more heat. Covering individual plants with a breathable material like horticultural fleece or a frost cloth can raise the ambient temperature by several degrees. Avoid using non-breathable plastic, which traps moisture and causes harm.
Spotting and Treating Cold Damage
Freeze damage in succulents typically manifests as a visual change in the plant’s tissues. Immediately after a freeze, the affected leaves may appear translucent, water-soaked, or wilted. They often turn black or dark brown as the damaged cells collapse, indicating the internal water has frozen and burst the cell walls.
If cold damage is suspected, avoid immediate pruning or watering. Pruning damaged tissue creates an open wound vulnerable to infection and stress. Instead, wait until the threat of frost has completely passed and new growth begins to emerge, typically in the spring.
Once new growth is visible, use clean, sharp shears to cut away the dead, blackened parts of the plant, cutting back to healthy tissue. Avoid watering until the cuts have calloused over. Then, resume a light watering schedule to encourage recovery, allowing the plant to focus its energy on new growth.