The olive tree is also a popular tub plant in this country, but how hardy is the Mediterranean plant? In this article you will learn which factors you need to consider for the right winter protection.
Olive tree: hardy, but sensitive to frost
The robust olive tree is easy to care for and, to a certain extent, hardy. However, since the tree originates from the Mediterranean region, it is only accustomed to light frost down to about minus five degrees. Especially at high altitudes, the thermometer in this country can drop to minus ten degrees or less. Such temperatures can harm the olive tree. Therefore, you should always overwinter olive trees in a container.
What else you should pay attention to and how you should care for your olive tree, you will learn in the next sections.
Olive tree: winter hardiness zones for orientation
If you want to overwinter your olive tree outdoors, you should make sure beforehand that it can really survive the cold. To do this, you need to take a closer look at the location of the tree and the winter climate that prevails there. To do this, you can use the geographical winter hardiness zones as a guide.
The scale includes a total of ten zones, which in turn are divided into half-zones a and b. Each temperature zone covers a range of 5.5 degrees Celsius. The home of the olive tree is in winter hardiness zone 8:
- Zone 8a: -12.2 degrees Celsius to -9.5 degrees Celsius.
- Zone 8b: -9.4 degrees Celsius to -6.7 degrees Celsius
You can use a winter hardiness zone map to check if your garden is in one of these climate zones. For example, some regions in western North Rhine-Westphalia along the Moselle River and in the Rhine Valley fall into this mild zone. If your garden is in this or a similar location, the olive tree is hardy enough for your garden. In other zones, you will have to take additional measures for winter protection outdoors or overwinter the olive tree indoors.
Additionally, olive trees are differentiated into hardy and winter hardy varieties:
Hardy olive trees can only be left outside in winter in regions with a particularly mild climate. They are very sensitive to frost. To be on the safe side, it is therefore better to overwinter them indoors or take additional protective measures to avoid damage from winters that are too cold.
Winter-hardy olive trees, on the other hand, can survive even in heavier frosts. Varieties such as ‘Cornicabra’, ‘Forma Toscana’ or ‘Frantoio’ can withstand temperatures down to minus ten degrees even without protection. However, if the thermometer in your region often drops below minus ten degrees, you will need to provide additional winter protection.
Olive tree: protective measures in case of severe frost
During severe winter frosts, even hardy olive trees need suitable winter protection. You can easily overwinter potted plants indoors, but planted olive trees should be protected from frost damage by other means:
Protect tree disc: The olive tree’s tree disc is the area where the tree transitions into the ground. This area is particularly vulnerable. The best way to protect it from the cold is to cover it with a layer of bark mulch, straw or brushwood.
Insulate the planter: If you have planted your olive tree in a container, you can wrap it with jute. This will prevent frost from penetrating and damaging the roots.
Wrap trunk and crown: Jute is also good for winterizing the crown and trunk of the olive tree. To do this, wrap the fabric generously around the entire tree. In this way, the olive tree is not only better protected from frosty nights, you also relieve the branches of some of the snow masses. Remove the cover on frost-free days so that the leaves get some sun.
Frost protection from below: Ground frost is also a danger to container plants and their roots. The best way to protect your olive tree is to place it on a wooden pallet with an insulating layer of straw or autumn leaves underneath.
More tips on the winter hardiness of the olive tree
If your garden is in the right winter hardiness zone, your olive tree already has a good chance of surviving the winter. But if you really want to play it safe, you should follow these tips:
Buy seedlings from regional nurseries. An olive tree grown in the regional climate is more winter hardy than an imported tree.
In regions with very early and very late frosts, it is better to overwinter the olive tree indoors.
Gradually decreasing temperatures harden the olive tree.