Cyclamen, particularly the popular Cyclamen persicum hybrids, are cherished for their elegant, upswept flowers and marbled foliage. To truly thrive as a houseplant and replicate the conditions of their native Mediterranean and Middle Eastern habitats, providing the correct temperature is paramount. From the plant's physiological perspective, temperature directly influences metabolic rates, respiration, photosynthesis, and overall vitality.
For a cyclamen plant, the ideal temperature range for active growth and sustained flowering is between **60°F and 68°F (15°C and 20°C)** during the day. Within this relatively cool bracket, the plant's biochemical processes operate at peak efficiency. Photosynthesis proceeds effectively without being hampered by excessive heat, which can cause the stomata to close to conserve water, thereby limiting carbon dioxide intake. This range also supports strong cell development, resulting in sturdy flower stems (scapes) that can hold the blooms upright without wilting and robust leaf growth. Nighttime temperatures are equally critical and should ideally drop to between **50°F and 55°F (10°C and 13°C)**. This daily drop mimics the plant's natural environment and is crucial for reducing respiratory loss of sugars accumulated during the day, allowing more energy to be directed toward flower production and longevity.
Temperatures consistently above **70°F (21°C)** trigger a stress response in the cyclamen. The plant perceives this as the onset of its native summer drought, its natural dormant period. In response, it will begin to senesce: flowering will cease abruptly, buds will yellow and drop without opening, and leaves will start to yellow as the plant redirects resources downward to its tuber in preparation for dormancy. High heat also accelerates the plant's respiration rate, causing it to consume its energy reserves much faster than it can create them through photosynthesis. This leads to a general weakening of the plant, making it more susceptible to spider mite infestations, which thrive in hot, dry conditions.
While cyclamen are cool-climate plants, they are not frost-hardy houseplants. Prolonged exposure to temperatures below **50°F (10°C)** will significantly slow growth and can lead to chilling injury. Temperatures at or below **40°F (4°C)** can cause severe cell damage, manifesting as soft, blackened foliage and collapsed flowers, often leading to the death of the plant. It is important to distinguish this cold damage from the plant's natural life cycle. A gradual cooling in autumn is a normal environmental cue, but a sudden, severe cold shock is destructive. Placing a cyclamen in a drafty window or against a cold pane of glass in winter can easily expose it to these damaging temperatures.
Understanding the cyclamen's life cycle is key to long-term care. After its main flowering period, typically in late spring, rising temperatures and longer days will signal the plant to enter dormancy. The leaves will yellow and die back as the plant conserves energy within its tuber. To support this process, it is best to place the pot in a cool, dark location for 2-3 months and withhold water. To break dormancy and initiate new growth, the tuber requires a period of cool temperatures. Bringing it back into a cool environment of **50-65°F (10-18°C)** will encourage fresh leaf growth, beginning the cycle anew.
