The survival of outdoor succulents during winter depends on protecting them from two primary threats: freezing temperatures and excessive moisture. Succulents store water in their leaves and stems, making their tissues vulnerable to bursting when the internal water freezes. Successful overwintering requires careful preparation and targeted protection strategies to ensure the plants remain both dry and insulated until spring.
Understanding Succulent Hardiness
The ability of a succulent to survive outdoors is defined by its cold hardiness, which separates species into two major groups. Hardy succulents, such as those in the Sempervivum (Hens and Chicks) and many Sedum genera, are native to mountainous regions and can tolerate freezing temperatures, sometimes down to -30°F, especially when dormant and kept dry. These species have specialized adaptations that allow them to endure snow and frost.
Tender, or soft, succulents like Echeveria, Crassula (Jade Plant), and Aeonium cannot tolerate temperatures below freezing and must be protected from frost. By knowing the lowest expected temperature for your zone, you can select the appropriate species or plan for necessary winter protection.
Succulents enter winter dormancy when exposed to cooler temperatures and reduced light, slowing their growth and reducing their need for water. This dormant state is crucial because a plant that is dry and metabolically inactive is significantly more cold-tolerant than one that is actively growing and plump with water.
Preparing the Environment (Soil and Location)
Preparation for winter must focus on mitigating the risk of root rot caused by persistent moisture, which is often more destructive than the cold itself. The planting medium must be extremely well-draining, requiring a high proportion of inorganic grit like pumice, coarse sand, or gravel, to prevent water from lingering around the roots. For potted succulents, ensuring the containers have large, unobstructed drainage holes is paramount, and terracotta pots are often preferred as they allow moisture to evaporate through the sides.
Strategic placement can significantly improve a plant’s chances of survival by leveraging natural microclimates. Positioning succulents on a slight elevation or slope encourages water runoff, preventing pooling. Choosing a location against a south-facing wall maximizes sun exposure and warmth retention, as walls can radiate stored heat back onto the plants at night. For potted specimens, moving them under the eaves of a roof or an overhang provides a permanent shield from direct winter rain and snow. Before the cold season begins, gently remove any dead or fallen leaves from around the base of the plant, as this organic debris can trap moisture and encourage fungal growth.
Active Cold and Moisture Protection
As cold weather approaches, completely cease watering to allow the soil to dry out fully, forcing the succulent into cold-tolerant dormancy. Once the soil is bone-dry, the plant can better withstand lower temperatures because there is less internal water to form ice crystals that burst cell walls. This cessation of water should begin well before the first expected frost, allowing time for the plant to dry out.
When a severe frost or prolonged cold snap is predicted, coverings become necessary for all but the most hardy, in-ground varieties. Frost cloth, spun nylon floating row covers, or even bedsheets can be draped over the plants to trap ground heat and prevent frost crystals from forming directly on the foliage. These materials must be breathable and should not be left on indefinitely, as they can block too much light and prevent proper air circulation, especially on milder days. For more intense protection, a cold frame or plastic sheeting can be erected over the area, but this must be vented during the day to avoid overheating and to allow moisture to escape, preventing a damp, rot-prone environment.
Identifying and Treating Winter Damage
After a severe cold event, it is important to accurately identify the type and extent of the damage before taking action. Freeze damage appears as translucent, water-soaked, or mushy spots, which quickly turn black or brown as the plant cells die from the expansion of ice crystals. In contrast, rot, typically caused by cold, wet conditions, starts at the base or roots and causes the stem and lower leaves to become soft, dark, and often foul-smelling.
Damaged tissue should not be removed immediately while cold weather is still a threat, as pruning too early can create open wounds that expose the remaining healthy tissue to further frost or pathogens. Wait until the danger of hard frost has completely passed, usually in early spring, before using sterilized tools to cleanly cut away any blackened or mushy portions down to healthy, firm tissue. Once the damaged material is removed, allow the cuts to callous over before considering a resumption of the watering schedule. New growth in the spring will indicate that the plant’s core and root system have survived and are ready to recover.