Even in the Mediterranean home of the oleander, it can get very cold in winter. However, this is not the rule, so the shrub - like other Mediterranean plants - is used to mild temperatures in the cold season. Slightly sub-zero temperatures are still tolerated, but if the thermometer falls well below zero, it is better to overwinter your oleander indoors.
What temperatures can an oleander tolerate?
Oleander tolerates mild temperatures, but temperatures below -5°C can cause damage. Frost-free wintering at 5-10°C is ideal. In summer, oleander thrives best in lots of sun and warmth.
Oleander is not hardy
Like so many Mediterranean plants, oleander is not frost-resistant and therefore not winter-hardy. Light frost of around minus five degrees Celsius is usually tolerated, but only for a very short time - the shrub quickly suffers frost damage, which manifests itself in brown, dried leaves and shoots. Leave the oleander outside in late autumn or in mild winters, but provide it with protection from the cold at night (for example a garden fleece (€6.00 on Amazon)) or, if the temperatures are expected to drop significantly, overwinter your oleander in a cool but frost-free room.
Overwintering oleander properly
Basically, the oleander should stay outdoors as long as possible and only be moved to winter quarters when the temperatures drop well below zero. How much frost an oleander can tolerate cannot be determined by specific degrees, but depends on the individual plant. Some oleander varieties (for example 'Papa Gambetta', 'Italia' or 'Lutein Plenum') are considered particularly frost-resistant, others are much more sensitive to cold. Older plants are also more robust than young ones. However, frost-free wintering is advisable for every specimen if possible.
Tip
In summer, on the other hand, it cannot be warm enough for the oleander, because it only shows its flowers when there is a lot of sun and warmth. However, if it is cold and rainy, the hoped-for flowering may simply fail. In this case, move the oleander into a winter garden - if available - and ensure sufficient brightness with plant lamps.
