When the olive tree suddenly loses most of its leaves, it is usually a warning signal. Here’s how to find out what’s wrong with your Mediterranean plant.
Olive trees (Olea europaea) are Mediterranean plants and love warm temperatures and dry soils. In temperate climate, the growing conditions for the olive are therefore not optimal. In most areas, olive trees can only be grown in pots, as the evergreen plants cannot survive harsh winters outdoors. Occasionally, the plant may lose its leaves. This can have several reasons.
Reasons why an olive tree loses its foliage
The olive tree is too dry
Although the olive tree is used to dry locations and well-drained soil from its southern European home, this does not mean that it likes to dry out completely. Especially in pots, the plant evaporates a lot of water in midsummer and so it happens quickly that the entire root ball dries out and the tree loses its leaves as a result. Therefore, especially in full-sun locations, make sure that the olive tree always has enough water without soaking the root ball. If it regularly happens that the soil dries out too much, you should give the olive tree a larger pot and add a substrate with water-retaining properties.
Waterlogging leads to leaf loss
However, worse than drought for the olive tree are wet feet. In this case, the leaves first turn yellow and then fall off. Therefore, to avoid waterlogging in the pot, be sure to include a drainage layer when planting and do not leave the olive tree in the water-filled saucer. Place the pot on clay feet so that the root ball is also ventilated from below. Waterlogging occurs especially in spring and fall when the tree is not yet in full sap and the gardener is too generous with watering, or in summer when the olive has been in the rain for a while. If the root ball is permanently too wet, the fine roots will rot and the olive tree will no longer be able to absorb water despite an abundant supply. Then the olive tree loses abundant leaves.
Especially in winter, the olive tree needs very little water. A glass full every two to four weeks is usually sufficient, as the tree is in winter dormancy during this time. If the olive tree has been standing in wet substrate for a few days, you should repot it in dry soil.
Problems in the winter quarters
Most often, the olive tree loses its leaves in the winter quarter. This is usually due to a mismatch of light output and temperature. The optimal wintering for the olive tree takes place at 5 to 8 °C / 41 to 46 °F in a room that is as bright as possible, for example, in an unheated winter garden or a glass house with a frost protection. If it is too dark for the olive tree, it will drop its leaves, as these consume more energy than they can supply through photosynthesis. However, leaf drop in the winter quarters is not a disaster. The olive tree is very regenerative and will sprout again the next spring. You can also overwinter your olive tree in a cool, dark place if a bright spot is not available, but then expect it to lose all of its foliage. Water a defoliated tree minimally, as it uses virtually no water.
In May, put the olive tree back outside in a sheltered spot and it will soon begin to sprout new leaves. If you do not have any cool winter quarters available at all, you can also place the olive tree in a warm place all year round. In this case, however, you will need a plant lamp to provide the tree with sufficient light during the winter months. However, this type of wintering is not recommended in the long term, because over the years the flowering and fruiting will suffer if the plant never gets a rest.
Nutrient deficiency as the cause of the loss of leaves.
This cause is rather rare and occurs exclusively in potted olive trees. Basically, the olive tree is not very hungry for nutrients. A small dose of liquid fertilizer every four weeks in summer is quite sufficient. However, if the olive tree has not been fertilized or repotted for several years, a nitrogen deficit may indeed occur. This first shows itself in a complete yellowing of the leaves, which eventually trickle to the ground. However, do not combat the nutrient deficiency with double the amount of fertilizer, but give the tree a single dose regularly between March and September. After a certain regeneration period, the olive tree will recover and sprout new leaves.
Olive trees suffer silently
The olive tree is slow-growing and therefore often reacts to care failures with a delay of several weeks. If you can not find an acute reason for the leaf fall, think a few days in the past. If there was a move, a lot of rainy weather or heavy cloud cover, these could also be reasons for leaf drop. Although the olive tree is an absolutely low-maintenance and undemanding co-inhabitant, you should always keep a watchful eye on the plant.