With their silvery foliage and picturesque growth, olive trees (Olea europaea) truly exude a Mediterranean flair in the garden. And in summer, the heat-loving shrubs also feel at home in more temperate climates. However, the cold, wet winter, which also occurs in Europe, is a problem for them. But the olive tree can also be overwintered in this country – as long as a few important points are taken into account.
Is the olive tree hardy?
As a Mediterranean plant, the olive tree prefers mild temperatures and is therefore only considered hardy to a limited extent. Light frosts with temperatures around -5 °C can usually be survived by an olive tree without damage. For young plants, colder winters and longer periods of frost, however, effective winter protection is necessary.
- wintering planted olive trees
Every now and then we come across a proud, old olive tree in Europe that was probably planted many years ago. But it is not so easy to decide whether you should try planting it out. Although Olea europaea is one of the more cold-tolerant species from the Mediterranean region, it is by no means absolutely hardy.
A rough rule of thumb for olive trees planted in the garden is that they tolerate temperatures of about -5 to -10 degrees for short periods.
So even in regions with mild winters, there is still a risk that olive trees planted in the garden will suffer frost damage – and even one frosty cold night can sometimes be enough. However, you can prevent this with conscientious winter protection, especially in the first few years after planting.
Note: The older the tree gets and the more it has been able to take root, the less sensitive it usually becomes to frosts.
Before the first night frosts are to be expected, you should act and pack the olive tree away for winter. Protect the tree disc as well as the trunk and crown. The trunk of the olive tree can be packed thickly with air- and light-permeable plant fleece and is then winter-proof. The crown is also wrapped in fleece. You can spread organic material on the tree disc, for example brushwood or a generous layer of leaves.
- overwinter the olive tree: Frost-free winter quarters for potted plants
Do you live in a region with harsh winters or is the risk of frost damage simply too high? Then there is always the option of cultivating it as a tub plant. In this way, the olive tree can easily be moved to a frost-free winter location. Important: The plants should remain outside until the first frost actually sets in.
When overwintering, the olive tree should be kept as bright and cool as possible, at temperatures of around 5 to 10 degrees Celsius. Unheated staircases or conservatories, a bright garage or a greenhouse that is kept cold are conceivable. Ventilate the room regularly and water only moderately during this time. The cooler the environment, the less water the olive tree needs.
If only a very dark room is available, the temperature should be very low throughout. It can then happen that the olive tree drops its leaves over the winter. Normally, the tree will sprout again the next spring. However, this is not an optimal solution.
Check the winter quarters for pests
Dry air in the winter quarters can sometimes be a problem for olive trees, which are actually so robust. Mealybugs and spider mites thrive in a warm, dry environment. Therefore, make sure that the temperatures are not too high.
Tip: If you discover pests on twigs or leaves, act quickly. Wipe off the affected areas thoroughly and then spray the tree with water.
- overwintering potted plants outdoors
If it is not possible to overwinter the olive tree indoors, the pot and crown must be protected as well as possible. Smaller pots should be placed in a cardboard box or wooden crate and additionally padded with straw or leaves. In addition, wrap the crown and trunk in air- and light-permeable fleece.
More tips for overwintering olive trees
Waterlogging is a particular problem for olive trees in winter and can even cause more problems than the cold. In the winter quarters you should therefore water little. If the tree is to be overwintered outdoors, it is best to keep it under a roof if possible. Good drainage is important for planted specimens. Yellow leaves in winter often indicate too much moisture. Although olive trees can overwinter outside in mild winters, in most cases it is advisable to bring the plant into a permanent winter home. Frequent moving is not good for the trees in winter. Young trees are generally more sensitive to frost, but there is still the potential for them to get used to the cooler climatic conditions over the years.