Around the Mediterranean, temperatures tend to be mild in winter. Severe frosts, snow and ice are extremely rare here. So it's no wonder that the Mediterranean oleander cannot tolerate the cold and therefore overwinters best in a cool, but frost-free place. However, the plant should not remain in winter quarters longer than absolutely necessary.
When can you put oleander outside?
After overwintering, oleander should be slowly acclimated to the sun at 5 degrees Celsius between the beginning and middle of April and placed outside for hours at a time. For specimens that have overwintered at warmer temperatures (from 10 degrees Celsius), this should be done from early to mid-May to protect sensitive shoots.
The colder the oleander overwinters, the sooner it can be cleared out
Oleander should overwinter as coolly as possible at temperatures around five degrees Celsius. Plants that are brought over the cold season at these temperatures can also be left in a darker place and oleanders that have overwintered earlier can be moved outside. Oleanders that have overwintered in a cool place can – depending on the weather – be put out between the beginning and middle of April – but initially only for an hour at a time. You should also protect the pots from the cold overnight with bubble wrap (€49.00 on Amazon) or something similar. Specimens that have overwintered at temperatures of ten degrees Celsius or more should only be allowed outside from around the beginning to mid-May. These oleanders have often already formed new shoots that are very sensitive to cold.
Oleander slowly get used to the sun
When clearing out the winter quarters, you should also not immediately put the oleanders in their usual place in full sun. The plant is no longer used to the effects and could suffer sunburn. It is also possible that it reacts to the sudden shock by dropping its leaves. Instead, initially place the oleander in a shady spot, as close as possible to a warm house wall, and slowly increase the amount of sunlight from day to day. If cold snaps are expected, it is best to put the plant away or pack it warm to protect it from frost. Otherwise they can suffer damage from the frost (e.g. dried leaves and shoots).
Cloudy or rainy days are ideal for clearing out
To protect the oleander from the harmful effects of the sun (keyword: UV light), preferably pick it up on a day with an overcast sky oron a rainy day from winter quarters. This gives the plant more time to get used to the new location and the shock of the change is not too severe.
Tip
The rule of thumb for overwintering oleanders is always: put the plants in their winter quarters as late as possible and take them out again as early as possible.