Geraniums - meaning the summer flowers that are often planted on balconies, not the native cranesbills - are considered to be particularly sensitive to temperature. That's not surprising either, since the plants that bloom so luxuriantly come from the south-east African desert areas and are therefore used to completely different temperatures than we are used to.
Geraniums do not tolerate temperatures below 5 degrees
Geraniums do not tolerate frost
This also means that geraniums do not tolerate frost. At best, the temperature should not fall below five to ten degrees Celsius during the growth period, because then the plant stops growing until it gets warmer again. An exception is hibernation, where the specified degrees are optimal - after all, the plant should not sprout prematurely.
Geraniums Temperature: Frost is particularly harmful at night
However, it does not harm the geraniums if the temperature falls below five degrees Celsius for a short time - provided there is no frost. In particular, the plants do not tolerate night frost, which is why they should only be planted out after the ice saints - when no more cold nights are to be expected.
tips
With appropriate weather, d. H. Outside temperatures in the two-digit range, you can put your geraniums on the balcony earlier. But then it makes more sense to bring the plants in overnight.