Lithops, commonly known as "living stones," are succulent plants native to arid regions of southern Africa. They thrive in environments with extreme heat, low humidity, and minimal rainfall. Their unique appearance and survival strategies, such as water storage in their thick leaves, make them highly adapted to desert conditions. Understanding their natural habitat is crucial to determining whether they can survive winter outdoors in the U.S.
Lithops are not naturally cold-hardy plants. In their native range, temperatures rarely drop below freezing, and they are accustomed to warm, dry winters. Most Lithops species can tolerate brief dips to around 40°F (4°C), but prolonged exposure to temperatures below this threshold, especially freezing conditions, can be fatal. Their cells are not equipped to handle frost, which can cause irreversible damage to their water-storing tissues.
The U.S. encompasses a wide range of climates, from tropical to arctic. Whether Lithops can survive winter outdoors depends heavily on the specific region:
Southern States (e.g., Florida, Texas, Arizona): In USDA hardiness zones 9-11, winters are mild, with temperatures rarely falling below freezing. Lithops may survive outdoors here if protected from excess moisture and occasional cold snaps.
Northern and Central States (e.g., New York, Colorado, Illinois): In zones 6 and below, winter temperatures regularly drop below freezing, making outdoor survival impossible for Lithops without significant protection.
Even in warmer regions, winter rainfall or snowmelt poses a significant threat to Lithops. These plants enter a dormant phase during winter and require little to no water. Excess moisture can lead to root rot or fungal infections, which are often more deadly than cold temperatures alone. Proper drainage and shelter from rain are essential if attempting to keep Lithops outdoors in mild climates.
For gardeners in marginally suitable zones (e.g., USDA zone 9), the following measures may improve Lithops' chances of surviving winter outdoors:
Mulching: A layer of gravel or sand can help insulate the soil and reduce moisture retention.
Covering: Use frost cloth or a temporary greenhouse structure to shield plants from frost and rain.
Elevated Planting: Growing Lithops in containers or raised beds ensures better drainage and allows for easy relocation during extreme weather.
In regions with harsh winters, Lithops should be grown indoors or in greenhouses where temperatures can be controlled. A sunny windowsill with minimal watering during dormancy mimics their natural winter conditions. This approach eliminates the risks associated with cold and moisture, ensuring the plants remain healthy year-round.
While Lithops are remarkably resilient in their native arid environments, their ability to survive winter outdoors in the U.S. is limited to the warmest regions with careful protection. Gardeners in colder climates should prioritize indoor cultivation to ensure these unique plants thrive.
