In summer it glows red, pink or white from afar from numerous balconies - it's geranium season! The popular summer flowers are ideal for keeping in containers and beautify many balconies and gardens. However, the plants are quite demanding in terms of temperature and location - the sensitive plants cannot tolerate frost at all.
Can geraniums tolerate frost?
Geraniums are sensitive to frost and can suffer damage at temperatures below 10°C, especially during night frosts. They should only be planted in pots or balcony boxes after the ice saints in mid to late May and brought into winter quarters in October before the first frost.
Geraniums need sun and warmth
Geraniums grow wild in the dry and warm climate of Southeast Africa - the cultivated ornamental geraniums in our native regions also need a similar climate. The plants react to temperatures below 10 °C by stopping growth and die in the event of light frost. The location should also be as sunny and protected from rain as possible, because geraniums react to excessive moisture and a lack of light with lazy flowering and various diseases.
There are no hardy “geraniums”
Sometimes “hardy” geraniums are offered in various shops. As a rule, however, this is not the species Pelargonium - which is also botanically correctly called Pelargonium in German - but rather the storksbills (lat.geranium). Although these are related to pelargoniums, in contrast to the flowers from Africa they are actually not very sensitive to frost and are hardy. If, on the other hand, “hardy” pelargoniums are offered, they can only tolerate very low temperatures for a very short time.
The right date for planting out
Due to their sensitivity to frost, geraniums should only be brought outdoors when no cold snaps or even frost are expected - night frosts are particularly dangerous. The flowers can tolerate temperatures of up to five degrees Celsius for a short time; at lower temperatures you should bring the plants indoors. According to an old farmer's rule, geraniums and other summer flowers belong outside after the ice saints in mid-May at the earliest, but better from the end of May.
Bring geraniums to their winter quarters in good time
What applies to spring is of course also relevant in autumn: Geraniums should be relocated to their winter quarters for the winter before the first frost - this point is usually in mid-October, but at the latest at the end of October. The plants should be heavily pruned and overwintered cool and frost-free at temperatures between five and ten degrees Celsius. As long as you have removed all the leaves, geraniums can also be stored in a dark cellar over the winter.
Tip
If there are cooler nights ahead in May but you no longer want to bring the geraniums into the house, then it is best to place the balcony boxes or pots directly against the house wall and cover the plants with an insulating fleece. If necessary, a thick layer of newspaper can also keep out some of the cold.