The olive tree only unfolds its Mediterranean flair with the right care. We show how, when and with what to properly fertilize your olive tree.
Olive trees (Olea europaea) originally grow in the Mediterranean region on barren, nutrient-poor and stony soil. They are very hardy and fairly undemanding. Due to the climate, most olive trees are cultivated in pots in our latitudes. Here the volume of soil and thus the supply of nutrients is very limited and regular fertilization is also necessary for the slow-growing trees and shrubs. When fertilizing olive trees, you should adapt to the individual nutrient requirements of the Mediterranean plant: the time of year, the age of the olive tree and the location determine the need for nitrogen, potassium and Co. An adapted fertilizer application at the right time is therefore essential for he althy growth and resistant Plants.
When do you fertilize olive trees?
Olive trees are only fertilized during the growth phase between April and September. When the olive tree hibernates during the cold season, fertilization is stopped entirely. Olive trees should be repotted every few years and transplanted into fresh, nutrient-rich potting soil. In the first few months after repotting the olive tree, no fertilization is necessary, unless deficiency symptoms appear. If an olive tree does not show any symptoms of deficiency and is growing he althy, it usually does not need to be fertilized.
Young olive trees up to the age of two years should only be fertilized to a very limited extent, if at all. A quarter to a third of the recommended amount of fertilizer is sufficient for them. Seedlings and cuttings are not fertilized at all.
Tip: In the case of planted trees, you can ensure increased winter hardiness by applying potassium fertilizer in the fall. The potassium helps harden the shoots and makes them less sensitive to frost.
At a glance: When should you fertilize an olive tree?
- Potted olive trees are fertilized during the growth phase between April and the end of September.
- Freshly repotted olive trees need in the firstMonths no fertilization.
- Olive trees that have been planted out usually do not need fertilizer, but autumn fertilization with potassium fertilizer increases winter hardiness.
- During the hibernation, the olive tree is not fertilized.
Detecting deficiencies in the olive tree
- Nitrogen deficiency: Even frugal olives can develop a nutrient deficit. This is usually due to a nitrogen deficiency. This is noticeable by yellowing of the leaves and stunted growth. If the plant has not been repotted or fertilized for a long time, a nitrogen deficiency is likely.
Note: Excessive watering and waterlogging of the roots can also trigger these symptoms. So before you reach for the fertilizer, you should check whether the water has been standing in the saucer for days or whether the soil has been wet for a long time. - Potassium deficiency: Potassium deficiency causes the leaf tips to dry up and even entire shoots to die off.
- Calcium deficiency: Olives prefer a slightly alkaline soil with a pH of 7 - 8. If the pH is too low, calcium deficiency can occur. This manifests itself in a yellowing of the leaves from the tip. The entire leaf is increasingly discolored and the veins are also lightening. Lime containing calcium increases the pH value and at the same time supplies the missing nutrient. However, first check the pH of the soil.
- Phosphorus deficiency: A pronounced phosphorus deficiency in olives and shows up as a reddish coloring of the leaves, but is extremely rare.
Fertilizer for olive trees: how much and how much to fertilize?
Special fertilizers for olive trees, lemons and co. have an optimal composition of nutrients for Mediterranean plants. They are usually commercially available under the name citrus fertilizer. If you don't want to buy a special olive tree fertilizer, you can use a balanced NK fertilizer. Phosphorus is required for flowering and fruit formation, but is usually contained in sufficient quantities in high-quality potting soil. Ideally, the fertilizer used should also contain traces of other nutrients, such as boron, iron, manganese, molybdenum and zinc. In high-quality potting soil, these trace elements are usually available in sufficient quantities until the next repotting.
Noteis also that an olive tree that gets a lot of light and heat grows faster than in unfavorable locations. It therefore consumes more nutrients here, which are reflected in a higher need for fertilizer. The type of fertilizer is also decisive for the frequency of fertilization.
Summary: How and how much should you fertilize an olive tree?
- Special citrus fertilizers are suitable in composition for olives and most other Mediterranean plants.
- Alternatively, universal fertilizers with an emphasis on nitrogen (N) and potassium (K), ideally with other micronutrients, can be used.
- Fertilization depends on age, location and type of fertilizer.
Fertilize olive trees primarily organically
Especially in the frugal Mediterranean trees, an organically emphasized nutrient supply is advantageous. The nutrients are stored in the soil and gradually made available to the roots. Fertilizers with a high proportion of organic matter, such as compost or liquid fertilizers that are easy to apply, such as our Plantura organic citrus & Mediterranean fertilizer, therefore have a gentle mode of action. Not only soil life benefits from the application of these fertilizers. There is also hardly any risk of over-fertilization. The use of plant residues from the food industry protects the environment and valuable resources. Olives are fertilized with our liquid fertilizer about every two weeks via the irrigation water. For this purpose, 15 - 25 ml of the fertilizer is mixed with 5 liters of water and the olive tree is then watered as required.
Fertilize olive trees with minerals
If the olive tree suffers from a severe lack of nitrogen, mineral fertilizers such as blue grain can quickly remedy the situation. This can be seen, among other things, in stunted growth or leaf fall after chlorosis. The nutrients are water-soluble in mineral fertilizers and are contained in a form that is directly available to the plant. In the long run, however, the administration of mineral fertilizers is not recommended. Especially with frugal plants like the olive tree, the risk of over-fertilization is high and the sensitive plant roots can be damaged. Heavy watering or rain also carries the risk of the water-soluble fertilizers being washed out. Furthermore, mineral fertilizers are usually associated with high energy consumption and costs for the environment.
Fertilize the olive tree with home remedies such as coffee grounds
Coffee grounds are a daily waste product in many households, but they still have a high nitrogen content. In small doses and superficiallyincorporated, this is slowly released. However, if you choose to fertilize your olive tree with coffee grounds, you should keep in mind that as they decompose, they lower the pH of the soil. Soil acidification can be remedied by fertilizing with crushed egg shells, which increase the soil pH.
Unusual fertilizers such as nails and hair can also be used in the garden as a substitute for horn shavings.
Home remedies include also plant extracts such as nettle manure. In addition to numerous micronutrients, fermented broths often contain not insignificant amounts of nitrogen and can even be used undiluted against pests such as aphids (Aphioideae). In the case of planted specimens, comfrey manure (Sympthytum officinale) can also serve as a source of potassium in autumn to increase winter hardiness.
Fertilize olive trees: recognize over-fertilization
Over-fertilization represents a much higher risk compared to insufficient supply. Over-fertilization often manifests itself in the form of burn symptoms, the so-called nutrient burn. Shortly after fertilization, the leaves develop yellow-brown tips and edges, which increasingly migrate inwards and cause the entire leaf to dry out. The leaves can sometimes curl up. Affected leaves usually fall off quickly. If only slightly overfertilized with nitrogen, the olive tree develops long, thin shoots and hardly ever forms flowers, but mainly leaves. Remedy in acute over-fertilization - for example through fast-acting mineral fertilizers - creates the repotting in fresh potting soil. As much of the over-fertilized soil as possible should be removed from the root ball or rinsed off.
Another important care measure for olive trees is the right cut. Find out how and when to prune olive trees in our special article.