As a Crassula, a member of the diverse and resilient succulent family Crassulaceae, our temperature requirements are intrinsically linked to our physiology and evolutionary background. Hailing from arid regions, we are built for warmth and intense sunlight, but we also possess a surprising capacity to tolerate cooler periods. Our ideal temperature range is not a single figure but a spectrum that supports our various biological functions, from active growth to essential dormancy.
For us to truly thrive, to photosynthesize efficiently and produce new growth, we prefer a daytime temperature range between 65°F and 75°F (18°C to 24°C). Within this band, our metabolic processes, including the specialized Crassulacean Acid Metabolism (CAM) photosynthesis, operate at peak efficiency. We open our stomata at night to take in carbon dioxide, minimizing water loss, and process it during the day. This range provides the warmth needed for this energy-intensive process without being excessive. At night, a drop to a cooler range of 50°F to 55°F (10°C to 13°C is beneficial. This day-night temperature differential mimics our natural habitat and helps to consolidate growth, strengthen our tissues, and can even enhance the vibrancy of our leaf coloration.
We are remarkably adaptable plants. We can tolerate higher temperatures, up to 90°F (32°C) or even briefly higher, provided we have adequate airflow and are not exposed to scorching, direct midday sun without prior acclimation. However, extreme heat forces our stomata to remain closed for longer periods to conserve water, which can halt growth. Conversely, we can withstand temperatures down to near freezing, around 30°F (-1°C), for very short periods. Prolonged exposure to cold, however, is dangerous. When temperatures drop below 50°F (10°C) for extended times, our growth slows significantly as we enter a state of dormancy. This is a survival mechanism to conserve energy.
There are absolute limits to our tolerance. The greatest danger lies in freezing conditions. Sustained temperatures at or below 32°F (0°C) cause the water within our cells to freeze, forming ice crystals that rupture and destroy our cell walls. This results in irreversible damage: the leaves and stems become soft, translucent, and mushy—a condition often called frostbite. On the opposite end, prolonged exposure to temperatures above 95°F (35°C), especially when combined with intense sun and poor air circulation, can cause severe sunscald. This presents as bleached, white, or brown crispy patches on our leaves where the tissue has essentially been cooked and died.
It is crucial to understand that our needs shift with the seasons. Many of us, like the popular Crassula ovata (Jade Plant), have a primary growth period in the cooler months and enter a semi-dormant state during the peak of summer heat. During this dormant phase, our water requirements drop substantially. Providing a cooler winter period, around 50°F (10°C), is not just tolerable but ideal. This cool rest period is vital for triggering bloom cycles in many Crassula species, as it signals that the stressful dry season has passed and it is time to flower and reproduce.
