Due to the lack of light in winter, lemons should always be stored cool but frost-free. At temperatures below 12 °C, the plants largely stop their root activities and require less light and nutrients, which means they can withstand the unfavorable light conditions much better. Loss of leaves towards the end of winter dormancy is not uncommon.
The optimal climate
Lemons kept in a tub overwinter best at temperatures of around five °C, although the thermometer can rise to up to 15 °C during the day. At night, around nine to twelve °C is optimal. These temperatures correspond to the natural site conditions of the lemon tree, although temperatures higher than 12 °C are not recommended in the long term. In this case, the tree would wake up from hibernation.
Provide sufficient light
Since lemons are evergreen, however, they need a certain minimum amount of light to maintain their vital functions, even during a cold winter. The light intensity that is usual in winter at this latitude is not sufficient for photosynthesis and thus for the formation of new assimilates - only a maximum of eight hours of daylight, filtered through the window glazing on top of that, has the effect on lemon trees like a permanent night. Therefore, lemons that have been overwintering in the living room often drop their leaves in spring or even react with dying branches because they have no energy reserves left.
What to do with light leaves?
Chloroses, lightening of leaves with leaf veins that remain green, are frequently observed deficiency symptoms. The reason for this is the cold nighttime temperatures during sprouting in spring and autumn, which make it difficult for the roots to absorb nutrients. A large or even complete loss of leaves, on the other hand, is almost always the result of a location that is too warm and/or too dark in winter. However, the plant usually drives out again.
High humidity in winter quarters
The third factor that affects the plants is humidity. Increased humidity in the winter quarters has both advantages and disadvantages.
Benefits of high humidity
- The reproduction rate of spider mites, which love dry climates, is greatly slowed down.
- If the buckets are not watered much in winter and a root ball dries up completely without being noticed, the plant still has the chance to get the necessary water via the leaves - drying damage is more easily prevented.
Disadvantages of high humidity
- The risk of gray mold rot (botrytis) appearing on immature shoots, wounds and young fruits is very high. If the shoot parts are not removed quickly, the fungus will continue to migrate up the branch towards the trunk.
- Any snails that have been brought in with you are encouraged by the humidity.
- If you prefer to overwinter the plants in an air-dry place, the risk of mites can be minimized by treating pests in autumn.
tips and tricks
Plant lamps should be installed as additional lighting in winter. Also pay attention to the heat generated by the lamps - neon lamps are recommended here, not least for cost-saving reasons.