Geraniums are not very cold-tolerant plants. Growth for even robust geraniums slows significantly at temperatures below 53.6°F (12°C)

. When temperatures drop below 41°F (5°C), their growth will come to a standstill, and frost can be fatal to them

. Geraniums can survive temperatures as low as 32°F (0°C), but night temperatures between 50° to 60°F (10° to 16°C) are best for them during the winter

. Standard geraniums can sustain light freezes, but temperatures below the upper 20s can inflict permanent damage

. Geraniums are native to South Africa, specifically the Table Mountain area, where the climate is similar to that of the steppes

. There, it rains infrequently, and the average annual temperature is 77°F (25°C)

. The temperature rarely drops below 41°F (5°C) in the winter months

. To protect geraniums from the cold

:

• Keep them close to the house wall, where they can benefit from the building's waste heat.
• Place them under a roof, where temperatures are higher than in the open air.
• Avoid placing them directly on the ground, as ground frost can still occur even when a thermometer at eye level shows positive degrees.