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Olive trees are becoming increasingly popular in Germany because they conjure up a Mediterranean flair on balconies and in the garden. They are relatively expensive to buy, so it's annoying when they end after the gardening season and freeze to death in the winter because they've been left outdoors. Hardy olive trees would be the solution to the problem. But does it exist? The plant expert answers the question.
Hardy olive trees?
Yes and no is the answer to the question of whether there are hardy olive trees. Varieties are available that are very sensitive to frost. These usually come from tropical areas where summer temperatures prevail all year round, such as in the Dominican Republic or large parts of Tunisia. The olive trees from there would not cope with the Central European climate in winter.
However, there are olive trees that have limited frost tolerance. These come mainly from the Mediterranean region, primarily from Spain and the Pyrenees. There, the temperatures in some regions fluctuate to lower levels. Olea europaea species derived from these species acclimate better in Central Europe and can tolerate sub-zero temperatures - but only with insulating protection against the cold.
Suitable hardiness zones
In mild regions, such as in wine-growing regions, conditionally hardy olive trees easily survive the cold season in the garden or on the balcony. Experience shows that temperatures down to -10 °C with cold protection do not bother them in other regions either. This means that "hardy" species are suitable for hardiness zones between 8 and 13 when provided with cold protection. As special breeds, a few specimens are cold-tolerant down to -20 °C or more. This corresponds to the maximum winter hardiness zone 6b.
notice: The winter hardiness zone is an international area classification based on the lowest annual average temperatures. Winter hardiness zones start at 1 with up to -51.1 °C and end at 13 with up to 21.1 °C.
risk of confusion
Caution is advised when buying an olive tree when it comes to labeling the frost resistance, because "winter hardiness" or "winter hardiness" can be mentioned here. One cannot be equated with the other.
winter festival
If an olive tree is described as winter-hardy, it can usually only cope with light frosts around 0 °C. Minus temperatures of up to 5°C usually do not cause any damage to plants as long as the temperature drop is only short-term. If the cold lasts longer, but protection from the cold does not help either and the hardy specimens must be resettled in a frost-free winter quarters. Only in mild regions can they remain outdoors in a cold and wind-protected location with thick protective insulation.
hardy
Hardy olive trees differ from hardy specimens in that they can withstand stronger and longer periods of frost. Frostbite damage is not to be expected, at least not to the extent that it leads to the death of the plant, as can be the case with hardy olive trees.
cold protection
Protection from the cold should be a must nowadays, even for hardy olive trees, because the Central European and German winters are becoming increasingly unpredictable. Temperatures above 0 °C can quickly drop far below the maximum frost tolerance of the hardy Olea europaea varieties. Ideal protection against the cold or optimal preparation for the winter can be achieved as follows:
- Fertilize Kalimagnesia at the end of the growing season - accelerates lignification, which provides greater resistance to cold
- Cover the surface of the earth with a thick layer of pine needles, leaves or straw
- Remove bark mulch under the insulating layer because of the risk of mold
- Cover the olive tree with fleece
- Alternatively, brushwood can be used
- Cover the bucket generously with plastic film so that the walls absorb the cold
- Alternative: Dig out the garden soil, place the bucket in it and fill in the side cavities with excavated soil
- Be sure to place the bucket on an insulating base - cardboard, styrofoam or wood is suitable
- Provide wind protection
- If possible, choose a bright, sunny location
- Avoid excessive wetness
- Ensure that the Olea europaea goes into winter healthy (more defenses and resistance)
tip: You should never make the mistake of letting an olive tree move into your living room for the winter. The lighting conditions there are too dark, there is usually a lack of humidity and the heat is not tolerated at all. An unheated, light-flooded conservatory is ideal when it gets too cold in the garden for partially hardy species.
Hardy Olive Tree Species
Real olive tree
The real olive tree (Olea europaea subsp. europaea) is the best-known and most widespread olive tree in Germany. It is considered one of the oldest plants among the olive trees. It includes numerous different varieties, some of which are hardy and tolerate temperatures down to -10 °C. They reach growth heights of up to 20 meters. They usually get gnarled with age. The most common varieties include:
- "Lessini" - very resistant to diseases - the best-known variety from Tuscany, Italy
- "Joven" - from Spain - does not need protection against the cold down to -5 °C
- "Forma Toscana" - from Italy - limited offer as it falls under cultural heritage
- "Plato" - from Spain - small in stature - ideal for planting in pots and tubs
- "Cuenco Diam - from Spain - winter protection recommended from -5 °C - usually offered as a round standard
More olive trees
- Arbequina - from Spain - silvery leaves - dark brown fruits with high oil content
- Cornicabra - from Spain - tested winter hardiness down to -13 °C - is one of the hardiest olive trees
- Empeltre - from Spain - fruit known for its mild oil with a sweet aroma
- Frantoio - from Italy - very resistant to diseases - low harvest - slim growth habit
- Hojiblanca - from Spain - formerly only cultivated for oil production, today very popular as a table olive
- Manzanilla Cacerena - Spain's most important table olive - high yield - hardy to -8 °C
- Nevadillo de Jaen - from Spain - dense growth - hardy to -10 °C
- Picual - from Spain - is one of the hardiest olive trees - is mainly grown for oil production
tip: Olive trees planted in pots feel the cold much more than the specimens planted in the garden. With these, it is advisable to already provide them with protection against the cold at temperatures just before freezing point.
Hardiest Olive Trees
The following varieties and species have proven to be even more frost-resistant. They can cope with temperatures of at least -20 °C and sometimes even colder conditions.
- "Aglandau": comes from France, Ukraine and Azerbaijan - carries popular, very aromatic oil and table olives
- "Bouteillan" - from the French Provence - is known for its resistance to cold - very productive
- "Moufla" - originally from southern France - hardy to -24 °C
- "Olivastra Seggianese" - from Tuscany in Italy - very easy to care for and easy to grow - olives are characterized by a fruity, slightly sweet aroma - today also at home in Germany and cultivated primarily for olive oil
- "Rougette de l'Ardèche'" - from south-eastern France - is the most cold-tolerant olive tree among French species - provides tasty, juicy table fruits - is ideal for oil production
Conditionally hardy/winterproof
19. "Ascolana" - comes from central Italy - tolerates short-term temperatures down to around -4 °C (USDA zone 9b)
Rare Varieties
20. Kalinjot - from Albania - well known for olive oil - hardy between -8 °C and -10 °C - specimens are very difficult to obtain in Germany
21. Kokërrmadh Elbasani - from Albania - hardy to -15 °C - very susceptible to diseases - harvest of table and oil olives
Hardy young plants
Young olive trees of hardy varieties should not stand outside in low minus temperatures for the first and, if necessary, the second winter. Because they are much more sensitive and their winter hardiness is not as pronounced as their adult counterparts.
species unknown
It is not always easy to distinguish between the different types of olive trees. If the olive tree plant in the garden or on the balcony was not bought with a name on it, or if the species/variety name has been forgotten, plant lovers cannot know whether their native specimen is hardy. Of course, you can call in an expert to have the plant clearly identified, or play it safe and let the olive tree hibernate at plus 5 °C.