Oleander (Nerium oleander) is a native to the mild winter Mediterranean countries. You can find out whether the lush flowering shrub tolerates frost and what temperatures are optimal for its growth by reading this article.
Table of Contents
Mediterranean flowering plant
In many Mediterranean countries, magnificent oleander bushes are known, which grow several meters high and give off a wonderful scent when they are in bloom. In Germany, however, the Mediterranean shrubs are mostly cultivated in tubs, as they are sensitive to cold and do not survive a typical German winter. Like many other Mediterranean species, oleander does not tolerate frost and is therefore not hardy. Only low minus temperatures of around minus five degrees Celsius are tolerated for a short time, although this information is not guaranteed. How much frost your oleander bush can withstand is very individual and depends on various factors:
- Location: sheltered versus exposed
- Variety: sensitive to frost vs. -insensitive
- Age: older bushes vs. younger
In principle, older specimens in sheltered locations are somewhat less sensitive to low temperatures than young oleander bushes in an exposed location.
Do not overwinter outdoors
Permanent temperatures below two degrees Celsius – in this case permanent means over a period of several days or even weeks – are not tolerated by the Mediterranean flowering shrub.
Even a single very cold night can cause frost damage. These are expressed in brown, apparently dried out twigs and shoots. In principle, these are not a problem and can simply be cut back. However, this only makes sense as long as the roots have not suffered any damage. Therefore, you should always cultivate the plant outside of its traditional habitat in tubs. Then you can bring it in when needed and overwinter frost-free.
Insensitive varieties
Occasionally one reads about “hardy” oleanders, which can withstand temperatures as low as minus 12 or even minus 22 degrees Celsius and can therefore be planted out in the garden without any worries. In fact, there are some new breeds that are much more robust and that temperatures of less than minus five degrees Celsius hardly bother. However, this information only applies to short periods of frost and under certain conditions. These varieties are not frost-resistant and therefore hardy in the true sense of the word. They’re just less sensitive. Ground frost and snowfall in particular make life difficult for these oleanders. This in turn leads to frost damage above ground or, if the roots are affected, to the death of the plant.
Nevertheless, it can make sense to choose such varieties. You can leave them outside for longer or remove them from the winter quarters earlier, thus minimizing the risk of winter damage. The following oleander breeds are considered to be particularly robust:
- ‘Atlas’: tolerates temperatures down to minus 20 degrees Celsius
- ‘Calypso’: down to minus 12 degrees Celsius
- ‘Cavalaire’: down to minus 22 degrees Celsius
- ‘Hardy Red’: down to minus twelve degrees Celsius
- ‘Italia’: down to minus 17 degrees Celsius
- ‘Jannoch’: down to minus twelve degrees Celsius
- ‘La Fontaine’: down to minus twelve degrees Celsius
- ‘Margarita’: down to minus 15 degrees Celsius
- ‘Provence’: down to minus 16 degrees Celsius
- ‘Villa romaine’: down to minus 15 degrees Celsius
If you want to plant one of these varieties in the garden, choose a sheltered spot without drafts. However, deep frost and bright sunshine can be problematic for these varieties: The oleander dies of thirst because it evaporates water but can no longer absorb moisture due to the frost.
frequently asked Questions
You should leave pot oleanders outside for as long as possible, ie with appropriate protection, the pot can remain outdoors in mild temperatures to just below freezing point. You should only move the plant to its winter quarters when it gets really cold, when the ground and/or frost sets in.
The optimal hibernation temperature is between two and ten degrees Celsius, depending on the amount of light available. In principle, you can hibernate oleanders in the dark, but then it must be as cool as possible. However, a brighter place is better (e.g. in a stairwell or unheated conservatory) where the plant is not exposed to drafts or the glaring midday sun.
