Even experienced gardeners can face such a nuisance as the yellowed leaves of tomatoes in a greenhouse. The reasons for this are completely different. It is very important to determine the source of the problem in time in order to find a solution and enable the tomatoes to grow and develop. Let us see why the leaves of tomatoes planted in the greenhouse turn yellow and determine possible solutions to this problem.
- Failure to meet landing dates
- Why leaves of tomatoes in a greenhouse turn yellow, root damage during transplantation
- The appearance of pests of tomatoes in the greenhouse
- Wrong watering of tomatoes in the greenhouse
- Lack of minerals
- The defeat of tomato diseases
Failure to meet landing dates
The reason why the leaves turn yellow in tomatoes may be non-compliance with the basic rules of transplantation. Here either the volume of land is not enough, or the seedlings were taken too overgrown.
Transplanting tomato seedlings in the greenhouse, you need to ensure that their root system does not form a lump, otherwise the plant will quickly begin to wither. 
The reason for this phenomenon is usually the fact that tomato seedlings had too little space in the container, they outgrew and therefore gradually began to die off.
While the culture was in the pot, it was imperceptible, but in the greenhouse, after planting, the leaves and the process begin to die out along with the roots. To avoid such trouble, you need to ensure that the seedlings do not overgrow in the container.
To do this, take a weak concentration of fertilizer solution. At the same time for one liter of water you need to take at least 10 g of top dressing. In this case, even if the affected parts of the plant die out, the new ones will develop quite well. But it is necessary to be prepared for the fact that the growth of culture for a few weeks will be delayed.Why leaves of tomatoes in a greenhouse turn yellow, root damage during transplantation
The reason why tomatoes turn yellow after transplantation can also be all sorts of mechanical damage to their root system.
This should not cause much excitementbecause the culture will take root in time, adventitious roots will appear, and, as a result, the color of the foliage will gradually recover. 
The appearance of pests of tomatoes in the greenhouse
Yellow leaves of tomatoes in the greenhouse is also due to pests. Wireworms, nematodes, and bears that live on the roots of the plant can live in the soil, causing damage to them. In such cases, you need to take action as soon as possible.
As for the wireworm, “Basudin” will help get rid of it. If the tomatoes turn yellow in the greenhouse because of nematodes, the ground should be completely replaced, since it is rather hard to fight them.Wrong watering of tomatoes in the greenhouse
In tomatoes in the greenhouse, the leaves also turn yellow due to improper watering, what to do about it, we will tell further. There are a number of requirements that must be observed when growing tomatoes.
- Soil moistening frequency. Tomatoes do not like daily watering. More preferable abundant, but rare soil moistening. Excessive watering will provoke the appearance of fungus on the site.
- Watering method. If the leaves of the tomato seedlings turned yellow, then perhaps watering was carried out not under the shrub, but on the leaves. In this case, they will turn yellow. It is important that water irrigates the soil, but not the leaves.
- Greenhouse moisture level. When deciding to grow tomatoes indoors, you need to be prepared for the fact that you need to monitor the indicator of humidity. Evaporation in greenhouse conditions is much slower than in open ground, and therefore the humidity will be much higher.
Lack of minerals
Another reason why tomato leaves turn yellow may be the usual lack of trace elements in them, because for tomatoes this factor is quite important.
- Lack of nitrogen. Tomato plants that suffer from nitrogen starvation usually look weak, their stems are thin, and the leaves are small. This nuisance can be solved by applying manure to the soil or fertilizers containing nitrogen in its composition. If manure is used, it should be diluted with water (1:10), and water the tomatoes with the prepared solution.
- Manganese deficiency. If tomato leaves turn yellow due to a shortage of manganese, what to do, we will tell further. In such plants, the leaves become light yellow in color, young leaves first suffer, and later older ones are also affected. Fertilizing the soil with a solution of mullein (1:20), as well as manure mixture (1:10) mixed with ash can solve this problem.
The defeat of tomato diseases
In the case when the root system of tomatoes is not damaged, pests are not observed, and the soil is sufficiently saturated with minerals,the cause of yellowing foliage can be a fungal disease.
- Fusarium. The disease manifests itself on the leaves of tomatoes in the form of a change in color and decrease in elasticity. This disease is spread through infected seeds or garden tools. If the fungus settles in the soil, then it can remain in it for quite a long time. The ideal conditions for its existence is a high temperature and an excess of moisture due to the daily abundant watering. Fusarium can manifest itself at any stage of tomato growth. It happens that the lower leaves turn yellow not only in mature plants, but also in tomato seedlings. The reason for this is the same fungus. If tomato seedlings or an adult plant have turned yellow, then the answer to the question of what to do is the use of various antifungal preparations. Best will cope "Trichodermin" and "Previkur."
- Late blight. On the foliage, this disease manifests itself as brown spots, which can gradually shift to the fruit. To prevent such a problem, you need to properly water the plant, not allowing water to fall on the leaves. You can fight the fungus with Bordeaux liquid, TATTO and Infinito preparations.
It is very important to be able to identify it in time in order to take appropriate measures as soon as possible and to ensure further high quality and quantity of the crop.
