The oleander (Nerium oleander) is originally native to the Mediterranean region. The winters there are mild with temperatures that rarely fall into the sub-zero range. For this reason, the popular but cold-sensitive flowering shrub cannot tolerate the typical German winter with frost, snow and ice.
How does oleander tolerate subzero temperatures?
Oleander can tolerate temperatures down to around -5°C, although older plants and certain varieties such as 'Villa Romaine' or 'Album Plenum' are more robust. For protection outdoors in winter, the planter should be insulated and placed near a warming house wall.
Overwintering oleander properly
For this reason, you should not overwinter oleander outdoors, at least not when temperatures permanently drop below zero. Theoretically, the Mediterranean ornamental shrub can tolerate temperatures below zero to around five degrees Celsius, although this information is not guaranteed - the actual robustness depends largely on the age of the plant, the type of overwintering and the plant pot. Basically, older specimens are significantly less sensitive to cold than younger ones. Oleander can also be hardened to a certain extent by overwintering the shrub at temperatures of around five degrees Celsius - of course above zero. Furthermore, certain oleander varieties are considered to be less sensitive to cold than others, for example 'Villa Romaine' or 'Album Plenum'.
When is the best time to bring oleander into your home
The general rule for oleander is to put it into its winter quarters as late as possible and put it out again as early as possible. It will be high time to clear up when the temperatures drop permanently below around minus five degrees Celsius and snowfall may be forecast. As soon as the weather becomes milder again, you can take the shrub outdoors again - ideally leave the pot near the winter quarters so that you can quickly move the plant back into the shelter if necessary. Cold-overwintered oleander can go outside from around the beginning to mid-April. However, specimens that have spent the cold season at ten degrees Celsius or more should remain in the cold protection room for another month.
Protect oleander outdoors from sub-zero temperatures
It is very important to always protect oleanders from the cold outdoors. Place the planter wrapped in bubble wrap (€49.00 on Amazon) or similar near a heat-emitting house wall, if possible on an insulating base made of Styrofoam.
Tip
If the oleander only freezes back above ground, it can be saved by severe pruning. In this case, the plant usually sprouts again. However, there is no hope if the roots were exposed to sub-zero temperatures and therefore froze.
