Planting tomatoes in the greenhouse, we want to get a big harvest and at the same time to justify the costs of cultivation.
Many novice gardeners, buying early highly productive varieties, forget that hybrids and varieties with high yields need to create ideal conditions in which timely feeding plays an important role.
Today we will understand the dressing of tomatoes in the greenhouse, and also talk about what fertilizers and when to use.
Fertilizers for tomatoes in the greenhouse: the basics of proper feeding
Let's start with the basics and talk about what kind of fertilizer is needed for tomatoes grown in the greenhouse. We will discuss the elements on which growth and development depends, as well as the size and taste of the fruit.
Macronutrients
Many gardeners and gardeners do not know that macronutrients are the usual NPK group, which includes nitrogen, phosphorus and potassium. These elements are necessary for all plants in the garden, in the garden and, of course, in the greenhouse.
Therefore, let us now understand what each element is responsible for, and how it affects the growth and development of the plant.
This macro is needed by plants in order to form a green aboveground part. In this excess of nitrogen leads to the fact that the plant begins to form too many leaves, processes and lateral stems to the detriment of fruiting. 
The absence of nitrogen leads to the fact that the green part is formed dwarf, the leaves are small and have a nondescript appearance, as if the light does not fall on them.
The element is responsible for the formation of the root system and fruiting. A sufficient amount of phosphorus reduces the time of transition to the formation of fruits, thereby reducing the time from planting to harvest.
Check out the undersized varieties of tomatoes for greenhouses.Also, importantly, phosphorus improves the immunity of plants, so cultures that receive a sufficient amount of this element are less likely to get sick and are affected by pests.
Overabundance of phosphorus leads to a lack of zinc, as it prevents the absorption of this trace element.
The most important food element, which is responsible for the resistance of the plant to adverse conditions, contributes to a better and faster maturation of products. 
It also increases the resistance to fungal diseases, which is very important in a greenhouse.
These macronutrients are the basis of mineral fertilizers for tomatoes in the greenhouse, so they are not only interrelated, but also play a major role in the formation of a full aerial part and good tasty fruits.
The absence or shortage of one of the elements entails a chain reaction, which ultimately leads to a decrease in yield.
Trace elements
Speaking about mineral fertilizers, we always imagine 3 main components on which growth and development depends, as well as yield. However, these processes are influenced by trace elements, as well as their number.
Of course, their role is not as important as macronutrients, but their absence will affect the general condition of the plant.
Necessary for the synthesis of enzymes, stimulates the development and formation of ovaries. It is also used to treat many diseases, so its introduction in the form of top dressing will help strengthen the immune system.
It plays a crucial role in the process of photosynthesis, so its absence causes the death of leaf plates, which are covered with dry spots.
Responsible for the biosynthesis of vitamins, is involved in metabolism.
The element increases the intensity of the formation of chlorophyll, therefore it is necessary in a small amount throughout the entire growth and development of the plant. 
Controls the exchange of macronutrients. Stimulates the fixation of nitrogen in the air.
It is a material for the synthesis of amino acids and in the future - proteins. Plays an important role in the transport of substances inside the plant.
Although calcium is considered by many gardeners to be a trace element, diminishing its importance, its amount in the soil should be the same as the number of macronutrients. Calcium is responsible for plant nutrition, ensuring a normal metabolism.
Did you know? Guano (bird excrement) has long been used as a universal fertilizer. For feces even fought, shedding blood. In the United States, a law was passed on guano, which allowed us to add any territories not occupied by another state where large amounts of bird excrement were found.
Features of greenhouse soil
For a gardener who has planted crops in open ground for years, it will be difficult to adapt to the conditions of the greenhouse, as the covered ground requires not only more attention, but also great efforts and financial costs. Next, we will understand what should be the soil in the greenhouse. 
To begin with, the greenhouse soil requires regular replacement of the upper layer. This is necessary in order to remove pathogens, as well as pests that often winter in the substrate.
However, they can not leave the greenhouse, as it is a closed room. Replacing the soil is needed for the reason that it is exhausted.
If you want to get a good harvest every year, then you need to replace the soil every time with a new, quite fertile one.
Now for the parameters of the substrate. The depth of the humus layer should be at least 25 cm. The acidity of the soil, depending on the crop, should be within strict limits.
Learn how to make a greenhouse according to Mitlayder and a "Signor Tomato" greenhouse with your own hands.In our case, the optimum pH value is 6.3-6.5. The percentage of organic matter in the greenhouse soil should be equal to 25-30. A lower content of organic matter significantly affect the yield of tomatoes.
Also important is the volume of air. From this indicator depends on how well the roots will be aerated, that is, to breathe. This show should be equal to 20-30%. It is not always possible to start a large amount of chernozem, and for some crops such soil will be unacceptable, so consider the ideal soil mix for greenhouses, which includes leaf, sod, loamy (in small quantities), peat land, as well as soil from an open garden plot and humus .
Sand, sawdust or straw can be added to the composition - the main thing is that the soil should be loose, light and fertile.
Important! We need the soil from the plot in order to “deliver” the necessary microflora to the greenhouse.
What fertilizers do tomatoes need?
Regardless of how fertile the substrate fertilizers for tomatoes in the greenhouse play an important role, so feeding must be carried out.
Speaking about what fertilizers tomatoes need, it is worth remembering what we wrote at the beginning of the article. 
Any plant needs both organic and mineral water, therefore, in fact, it will be necessary to feed everyone, but in different doses and quantities.
It is worth noting that the tomato "pulls out" more potassium and nitrogen from the soil, but a sufficient amount of phosphorus is needed to form large and tasty fruits.
This element is best made in the form of granular superphosphate, so that the maximum part of the element is available to the plant in the desired simple form.
Much also depends on nitrogen and potassium, but these are the elements that, as mentioned above, are absorbed most quickly and best by the plant, so it’s certainly not worth saturating the soil with them, otherwise you will get “two-meter-long” bushes that will grow tomatoes with cherry and will be a concentrate of nitrates.
In order for the plant to receive nitrogen in the most "comfortable" form, it is better to use ammonium nitrate or another ammonia variant. 
It turns out that before picking the plants into the greenhouse, we need to purchase the main macronutrients in the form described above, to purchase a small amount of organic matter, as well as several packages with trace elements that are used specifically for tomatoes.
Mineral or organic fertilizer?
Tomatoes should receive a variety of top dressing when grown in a greenhouse, therefore, it is difficult to say what is more important - organic or mineral water, but we will try to figure it out.
So, we found out that without mineral fertilizers, our tomatoes, even being high-yielding, will not make us happy because they simply will not get those elements that are necessary for growth.
To make it easier to understand, it is worth comparing plant nutrition with human nutrition. Although this is a fairly rough comparison, however, nitrogen, phosphorus and potassium can be compared with proteins, fats and carbohydrates.
In the process of feeding, we need these elements as well as the plants need an NPK complex.
If a person goes in for sports, he calculates the amount of proteins, fats and carbohydrates in order to gain an ideal mass, or vice versa - lose those extra pounds. 
To do this, in addition to the usual food, it consumes special additives, which, like mineral fertilizers, contain only some elements.
At the same time, a person cannot live only on artificial additives, and he still needs good nutrition, just like plants. Tomatoes will not grow only on mineral fertilizers, if they are planted in the sand.
Therefore, culture needs both mineral water and a sufficient amount of organic matter, the only question is when organic fertilizer should be applied.
If mineral water is brought in the right form during the growth process, then it immediately “supplies” all the necessary elements to the tomatoes that support growth and development, as well as affect the size of the berries. In this case, organic matter, embedded in the ground, will not give the tomatoes anything until it declines.
As a result, we can conclude that organic matter needs to be laid in the soil at least a quarter before the pickling of the seedlings is performed, so that the fertilizers can decompose into simpler elements available to the crop. It is important to remember that tomatoes do not like a large amount of organic matter. If the soil is strongly “oily” from an excess of humus or compost, then such a substrate will be less granular, heavier and, as a result, uncomfortable for tomato.
When and what spend feeding
We now turn to the discussion of the period during which fertilizers need to be applied and how to properly conduct them.
Top dressing scheme for closed ground
During the season you need to fertilize 3 times:
- The first fertilizer is applied 2 weeks after picking the seedlings for shelter. We need to dilute the following composition in 100 liters of water: 200 g of ammonium nitrate, 500 g of double superphosphate, 100 g of potassium chloride.
- The second dressing needs to be poured at the root at the time of formation of the ovaries. For the same 100 liters, we take 800 g of superphosphate and 300 g of potash nitrate.
- The third dressing is carried out during fruiting. At the same displacement we take 400 g of double superphosphate and 400 g of potash nitrate.
You can also use special complex fertilizers that are designed specifically for feeding tomatoes. 
Such complexes have a full-fledged balanced composition, which makes it possible to immediately apply all fertilizers, and not to mix, during which you can make a mistake.
Three feeding - this is the minimum from which you want to make a start when growing tomatoes in the greenhouse.
If you produce two or even one dressing, then the effectiveness of fertilizers will decrease by several times, because you, having supported the tomatoes at one stage and increased their needs, leave them without “food” at other stages.
As a result, the plant will not be able to produce food of green mass and fruit ovaries, because of which it can get sick or give a poor harvest.
Did you know? At the beginning of the XIX century, farmers did something that wasn’t embedded in the ground. as a fertilizer: feathers, fine sea sand, dead fish, mollusks, ash, chalk, and also cotton seeds. Only some fertilizers that really worked have survived.
Fertilizers in the germination of seeds and growing seedlings
If you buy really high-quality seed, which belongs to productive varieties or hybrids, then you should not carry out any preparatory actions, as this will not do anything. 
Firstly, the manufacturer has already carried out disinfection, therefore, it does not make sense to “bathe” the seeds in potassium permanganate, and secondly, the germinating seeds will germinate like this if there is a good substrate, regardless of whether you have first germinated them or not.
Important! If you sow the collected seeds, then you must “pickle” them in a solution of potassium permanganate.
The first fertilizer we will make only after the pick. Prior to this, tomatoes will draw all the nutrients from the soil, so prepare a good peat-based substrate for plants.
It is better to use the shop ground, as the street option will in any case have to be steamed to kill all the bacteria and fungi.
15 days after the dive we make the first fertilizer. In order for the plants at the first stage not to experience a shortage of any substances, it is necessary to introduce complex fertilizer, which will include the main NPK complex, as well as all trace elements (the full list is set out below). 
In this case, be sure to pay attention to the form of microelements, since we need exactly the chelate, and not the sulfate form.
The second option is divided into such substances that are not available for young plants. As a result, the tomatoes will experience starvation, although there will be plenty of top dressing in the soil.
Next, follow the development of plants. If you notice that the tomatoes are stunted, or there is noticeable inhibition in development, then, not earlier than 10 days after the first one, carry out the second dressing.
You can make as a special complex mixture, and your version: 1 g of ammonium nitrate, 8 g of superphosphate and 3 g of potassium sulfate. This composition should be diluted in 1 liter of water. For each bush spend about 500 ml.
Fertilizers when planting tomato seedlings in the greenhouse
A day before landing in the greenhouse in the wells you need to make a weak solution of manganese, as well as put a small amount of ash (about 100 g), finely crushed eggshell. Potassium permanganate will help to disinfect the soil, rid it of harmful bacteria and fungi. 
It is worth noting that we need ash from burnt straw or sunflower, as it is rich in potassium. Another option would be less useful for seedlings.
Please note that it is not possible to apply any mineral fertilizers directly into the hole, since you can seriously harm the root system of tomatoes if it comes into contact with concentrated fertilizer.
For this reason, do not add anything other than the mixtures listed above to the well. Also, do not put humus, and even more so - manure.
How to feed tomatoes after planting in the greenhouse
When planting in a greenhouse, plants in a stressful state should be watered with green infusion, which can be prepared without extra costs.
For the preparation of food, we need fresh chopped green nettle, plantain and other herbs that do not emit dangerous substances (ambrosia, hemlock and similar weeds can not be used). 
Next, the grass is mixed with wood ash and mullein, mixed well and left for 48 hours. After this, the infusion should be diluted with a large amount of water (at least 1 to 8) and shed every plant. Application rate - 2 l.
Next steps: tomatoes in bloom
We turn to feeding tomatoes in the greenhouse during flowering.
During flowering, our bushes have a serious lack of phosphorus and potassium, but nitrogen is not necessary for tomatoes at this time, so there is no question about any nitrogenous fertilizers.
It should be warned that during flowering to use urea solutions is prohibited, since it contains just a huge amount of nitrogen. Nitrogen during flowering will lead to inhibition of the process and further increase in green mass.
Below we look at nutritional yeast, which is a cheap growth promoter. So, it is the yeast top dressing that is best suited at the flowering stage.
Also excellent result gives treatment with boric acid, which not only activates flowering, but also prevents the shedding of peduncles. To prepare the solution you need to take 10 g of boric acid and dissolve in 10 liters of hot water. 
You will probably be interested to know how and why to process tomatoes with boric acid.The liquid should not have a boiling point, which is very important. After cooling, the solution is sprayed with flowering tomatoes. On 1 square consumes about 100 ml.
Also, tomatoes after feeding in the greenhouse with boric acid are not affected by phytophthora, as boric acid is used to treat this disease.
You can use standard potash and phosphate fertilizers, which will give a good result.
Do not forget that the greenhouse is a closed room in which there are no drafts and wind, therefore pollination is very bad and slow.
In order to speed up the process and increase the number of ovaries, it is necessary to ventilate the greenhouse during flowering, and also gently shake the peduncles so that the pollen is picked up by the wind and transferred to other plants. 
Extra root fertilizers - top dressing of tomatoes in the greenhouse
In conclusion, let's talk about whether foliar feeding is needed, what substances need to be sprayed, how they will affect the yield of the tomato.
How to recognize the need for foliar feeding
Immediately it should be said that foliar feeding is good micronutrients, which are required for the plant in small quantities.
The microelements that we described at the beginning of the article are used, but constantly sprinkling all of the above is expensive and meaningless, since an overabundance will also cause problems for the culture.
- Boron
The twisted tip of the shoots with a yellowed base and brown spots on the fruit are the result of a lack of boron. 
- Zinc
- Magnesium
- Molybdenum
Read also about how to get rid of kladosporioza, powdery mildew, Alternaria, top rot on tomatoes.
- Calcium
The lack of this rather important element is strongly noticeable on the bushes of tomatoes. It all starts with the deformation of the tips of young leaves, after which the surface of the leaf plates begins to dry.
Old leaves grow in size and become darker. Top rot appears on the fruit, which is why they can not last long. With a serious lack of calcium, the growth of the plant is severely inhibited, and the tip begins to die off.
Important! Calcium deficiency contributes to an excess of nitrogen, because of which the element is poorly absorbed and absorbed by the plant.
- Sulfur
It should be noted that the lack is noticeable on young leaves, and only after that - on old ones.
- Iron
- Chlorine
- Manganese
It also manifests itself as an iron deficiency, however, in the event of a shortage of manganese, yellowing does not begin strictly at the base, but spreads randomly. Only a part of the sheet may turn yellow, while the veinlets will strongly contrast with the rest of the sheet. 
As you can see, the lack of each element is very pronounced both on the appearance of the bush, and on its growth and development.
Did you know? The first chemical fertilizer was created by John Lowes at the end of the XIX century, who lived in England. It was called lime superphosphate and, accordingly to the name, had phosphorus in its composition.
Foliar fertilizers to compensate for the deficiency of nutrients
Consider feeding tomatoes in the greenhouse folk remedies.
In addition to factory mineral fertilizers, you can also use home-made fertilizers, which will help your tomatoes quickly gain the right weight and go to the fruit formation stage.
In this case, iodine will have two functions: to accelerate the ripening of fruits and protect tomatoes from late blight. It is best to feed at the time of ripening berries to speed up the process. For the preparation of top dressing we need a pharmacy alcohol version of iodine. On 100 l of water we drip 40 drops, mix well and spray each bush using 2 l of solution.
It should be understood that fertilizing tomatoes in a greenhouse with iodine is made only at a certain stage and only once or twice, since the plant does not need a plant in large quantities.
Wood ashes contain the whole complex of useful microelements which are so necessary for tomatoes. In this case, the ash can be applied in a dry form or foliar treatment can be done by spraying.
To prepare an aqueous solution of 100 liters of water, you need to take 10 glasses of ash, mix thoroughly and spray the plants. Norm - 1.5-2 liters.
Feeding tomatoes in a greenhouse with ashes can be carried out at various stages of growth and development, however, immediately after pickling, use ash solution is not recommended. 
Not all gardeners know why to use ordinary yeast for top dressing. The fact is that this product combines the action of the NPK group, as well as saturates the soil with beneficial microorganisms that strengthen the immunity of plants. In fact, yeast works as a cheap growth stimulant.
Important! Yeast does not contain nitrogen, phosphorus and potassium, but the effect of this additive is similar to the action of the NPK group.
To spend for tomato feeding in the greenhouse yeast, you need to prepare the correct composition.
- First option. A small bag mixed with 2 tbsp. l sugar, then add warm water in such quantity that the mixture becomes liquid. Next, the solution is added to 10 l of water. It consumes 0.5 liters per plant.
- The second option. We take a jar of 3 liters, two-thirds filled with black bread and fill to the top with water with dissolved yeast (100 g). We put the bank in a warm place for 3-4 days. After which the infusion is filtered and diluted in 10 liters of water. 500 ml is consumed for a young plant, 2 liters for an adult.
Now you know all about feeding tomatoes in a greenhouse made of polycarbonate or film. Use this information to grow a large number of tasty and healthy tomatoes.
Also remember that oversaturation of the earth with mineral fertilizers leads not only to an increase in yield, but also to a deterioration in taste, as well as an increase in the content of harmful compounds.
Therefore, if you want to continue to sell products, then be careful with the introduction of large doses of certain elements.
