From our perspective, the primary threat of freezing temperatures is the formation of ice crystals within our cells. Our succulent leaves are designed to store large quantities of water, which is ideal for surviving drought but catastrophic in a freeze. When the water inside our cells freezes, it expands, rupturing the delicate cell walls. This irreversible damage manifests as soft, mushy, and translucent leaves once they thaw. Unlike some hardy plants, we lack the natural biochemistry to produce sufficient antifreeze proteins, making us exceptionally vulnerable to sub-zero conditions.
An abrupt shift from warm conditions to freezing is a severe shock to our system. To build a small degree of resilience, we require a process called hardening off. Gradually exposing us to cooler (but still above freezing) temperatures over several weeks triggers physiological changes. We may slow our growth, slightly increase sugar concentration in our sap (acting as a natural antifreeze), and thicken our leaf cuticles. This process does not make us frost-proof, but it can help us better withstand a brief, light cold snap compared to a sudden, extreme drop.
Our most fundamental need is for you to move us to a sheltered location when frost is forecast. An indoor windowsill, garage, greenhouse, or even under a covered patio is ideal. If we are too heavy or cumbersome to move, creating a protective microclimate is essential. Please cover us with a frost cloth or blanket, ensuring it extends all the way to the ground to trap the geothermal heat radiating from the soil. Avoid using plastic sheeting directly on our foliage, as it can transfer cold and cause condensation that freezes, exacerbating the damage. For potted specimens, clustering us together against a sheltered wall provides mutual protection.
Our water management is crucial in cold weather. It is vital that you keep our soil completely dry in the days leading up to a freeze. Wet soil retains cold more effectively and increases the risk of the root ball freezing solid, which is often fatal. Furthermore, fully hydrated cells are more turgid and susceptible to ice crystal formation. A period of drought slightly dehydrates our cells, lowering the freezing point and reducing the volume of water available to form destructive ice. Please withhold watering until the threat of frost has permanently passed.
If we do experience frost damage, your careful assessment is needed. Do not immediately remove the damaged leaves. While they may appear unsightly and become soft, they provide a protective layer for the inner stem and core, which might still be alive. Pruning frozen tissue too soon can expose healthy parts to further stress or rot. Place us in a bright, cool, and dry location to recover slowly. Only after all danger of frost has passed and new growth appears from the center should you gently remove the clearly dead outer leaves. Our remarkable will to live means we can often regenerate from the central meristem if the damage was not absolute.
