Yellow leaves on the lemon tree: causes and treatment

Why is my lemon tree getting yellow leaves? We explain what can cause it and how to get rid of it.

Yellow leaves on the lemon tree (citrus x lemon) are always a clear sign that something is wrong with the nutrient supply or care. The task now is to find and eliminate the cause of this yellowing, also known as chlorosis. Because over time, your lemon tree will gradually shed its leaves and may even die. Nevertheless, yellow leaves or a slight loss of leaves are not a reason to panic at first. Once the cause has been found, the tree can usually be easily cured. Even if your lemon has already lost all its leaves, it can sprout again fresh.

Recognizing chlorosis in the lemon tree

As a rule, chlorosis in lemons and other members of the rue family (Rutaceae) always looks quite similar from: Due to a lack or degradation of chlorophyll, the green leaf pigment, the leaves on the lemon tree discolour yellow. Sometimes the whole leaf is affected, sometimes only the spaces between the leaves, while the veins remain green. Untreated chlorosis severely weakens the affected plant and in some cases can even lead to the death of the entire plant.

Causes of yellow leaves on lemon trees

Chlorosis can have various causes. Every now and then some old leaves turn yellow. But if many leaves are affected at the same time, this is a clear warning signal. It can indicate different problems:

• waterlogging: Frequent watering is well intentioned, but can quickly become too much for the Mediterranean plants. If waterlogging forms, the roots begin to rot and the leaves turn yellow. Check if the soil is heavily soaked or if there is water in the planter.
• Dryness: Long periods of drought can also lead to yellow leaves. The leaves are then often slightly curved. This type of chlorosis is rare on lemon trees.
• iron deficiency: Various deficiency symptoms of the lemon tree are expressed in leaf chlorosis. Iron deficiency is most common in lemon trees. The still young leaves and shoot tips turn completely yellow to almost white from the edge of the leaf inwards. Lemons have a high iron requirement. Too high or too low a pH value in the soil binds the existing iron and the plant can no longer absorb it. A pH value between 5.0 and 7.5 is ideal for the lemon tree.
• Magnesium deficiency: Yellow leaves with green veins are typical of a magnesium deficiency in the lemon tree. The yellowing begins first on the old, lower leaves. The leaf veins remain dark green in the middle for a long time and stand out clearly. Acidic soils with a pH below 5 fix the magnesium in the soil. The plant then increasingly suffers from deficiency symptoms because it can no longer absorb the nutrient.

• Nitrogen deficiency: Lemons may lack nitrogen if they haven't been fertilized or repotted for a long time. Chlorosis begins on the lower, older leaves. After a while, these tend to fall off. The yellowing then slowly spreads upwards towards the young leaves. A lack of other elements - such as zinc or molybdenum - can also cause similar symptoms, but only occurs very rarely.
• Cold: Lemon trees need warmth and their roots quickly suffer from low temperatures in winter. If these sink too much in the winter quarters, yellow leaves form on the lemon. In this so-called winter chlorosis, the leaf veins turn yellow first. A mat or styrofoam plate under the pot protects the roots of the lemon tree from too much cold. The temperature during the winter should be around 3 to 10 °C. As the temperature increases, winter chlorosis will resolve itself.
• Wrong location: An unsuitable location can also lead to yellow leaves and leaf shedding. Drafts or a lack of light may be the causes. Especially in the winter quarters, a combination of too much heat and too little light is often responsible for discoloration of the leaves and leaf fall. But be careful: Changing the location too often also causes stress in the plant.

Combating and avoiding yellow leaves on the lemon tree

Different causes call for different actions – but how do you tackle the causes of lemon tree chlorosis?

• In case of waterlogging first of all helps to water less. Especially in the cool winter quarters, when the plant hardly evaporates any water, it should only be watered very sparingly. To prevent waterlogging, permeable soil, a drainage layer and good drainage in the pot are helpful. However, repotting the plant as an immediate measure only makes sense in spring at the beginning of the new vegetation period, as plant growth is stimulated by repotting.
• When dry the plant should be sufficiently watered, especially during the growing season in the warm months. But first make sure that dryness is really the trigger for the yellow leaves. Well-intentioned watering often only damages already weakened lemon trees when drought is not the actual cause.
• With nutrient deficiency is the right one Lemon tree fertilization decisive. Many nutrient deficiencies can be corrected using a primarily organic liquid fertilizer like ours Plantura Organic Citrus & Mediterranean Fertilizer, fix it quickly and effectively. In addition to the main nutrients nitrogen and potassium, iron is also included in addition to other minerals, so that the liquid fertilizer can also be used against iron deficiency symptoms. However, keep in mind that even if there are signs of deficiency, you should no longer fertilize from August until next spring. Preventive against nutrient deficiency is the regular Potting up the lemon.

Tip: Additional magnesium deficiencies can be remedied by spraying the leaves with a special magnesium fertilizer. Adjusting the pH value, for example by repotting in suitable soil or lightly liming, is usually sufficient.

• In case of wrong location you should of course find a new place for your lemon tree. The lemon prefers sunny, warm and sheltered locations. Cold drafts, on the other hand, can damage the lemon tree. Therefore, think carefully about whether the planned location is really suitable, because a change of location also brings new stress with it.

Prevent chlorosis on the lemon tree

The cause of iron deficiency and the associated chlorosis often lies in the soil. The soil of purchased potted plants is usually of poor quality and the plant should therefore be repotted to prevent chlorosis. For repotting, we recommend high-quality, loose soil with an optimal pH of around 5.5 to 6.5. It doesn't necessarily have to be a special one citrus soil be. Suitable potting soil can be improved with sand, bentonite or other loosening materials and thus mixed yourself.

It is much more important that as much of the old soil as possible is removed when repotting without damaging the roots. Alternatively you can use the Determine the pH of the soil, for example with a pH value measuring set. If the pH is actually too high or too low, it can be mixed with something Epsom salt lowered or carefully raised with a light application of lime.

Notice: Citrus plants in general only require small amounts of the plant nutrient element phosphate. That's why it's practical to use phosphate-reduced citrus fertilizers like ours Plantura Organic Citrus & Mediterranean Fertilizer to use, because this not only meets the needs of the beloved lemon, but also saves finite resources.

Yellow leaves and leaf fall are often accompanied by a failure to flower. In our special article you will find out why this is so and what other reasons it may have that your Lemon tree not blooming.