Even in the Mediterranean homeland of the oleander, it can get very cold in winter. However, this is not the rule, so that the shrub - like other Mediterranean plants - is used to rather mild temperatures in the cold season. Slight minus degrees are still tolerated, but if the thermometer falls well below zero, it is better to bring the plant indoors.
The oleander comes from the warm Mediterranean region
Oleander is not hardy
Like so many Mediterranean plants, oleander is not frost-resistant and therefore not hardy. Slight frost down to about minus five degrees Celsius is generally tolerated, but only for a very short time - the shrub quickly suffers frost damage, which manifests itself in brown, dried-up leaves and shoots. Leave the oleander outside in late autumn or in mild winters, but provide it with protection from the cold at night (e.g. a garden fleece) or, if the temperatures are to drop sharply, bring it into a cool but frost-free room.
Properly wintering oleanders
Basically, the oleander should stay outdoors for as long as possible and only be moved to the winter quarters when the temperatures fall well below zero. How much frost an oleander tolerates cannot be determined by specific degrees, but depends on the individual plant. Some oleander varieties (e.g. 'Papa Gambetta', 'Italia' or 'Lutein Plenum') are considered to be particularly frost-resistant, while others are much more sensitive to cold. Older plants are also more robust than young ones. However, a frost-free hibernation is advisable for every specimen.
tips
In summer, on the other hand, it can't be warm enough for the oleander, because it only shows its blossom splendor when there is a lot of sun and warmth. If, on the other hand, it is cold and rainy, the hoped-for flowering can simply fail. In this case, put the oleander in a conservatory - if there is one - and ensure sufficient brightness with plant lamps.