How to harden tomato seedlings

Hardening tomato seedlings is an important stage in the cultivation. Thanks to this process, the root system does not dry out, and the plant does not fade and gives juicy fruits.

Hardening tomato seedlings

Tatyana Orlova (candidate of agricultural sciences):

Hardening of seedlings is not only an increase in its resistance to low temperature of open ground, but to the whole range of external environmental influences: wind, heat, precipitation.

When to start hardening

How to temper tomato seedlings is a common question that arises among gardeners. Healthy, strong and developed tomato seedlings are obtained only if the hardening process lasts from the moment of sowing the seeds and until planting in the ground. The hardening of young tomatoes is needed so that the bushes adapt to the new growing conditions.

It is recommended to start hardening tomato seedlings in the spring, in April. Proper hardening of tomatoes and top dressing make the plant stress-resistant when transplanted into open ground.

Signs that the seedlings are ready for hardening and may soon be transplanted into the ground:

  • Leaf color. They should be dark green with a purple hue. In the presence of white or other spots, it is not recommended to temper the seedlings.
  • The condition of the stem. Sagging and falling under its own weight, the stem shows that the vegetable crop is prone to drying out. It should be bright green and straight.
  • Root system. If it is powerful, strong and developed, it will help the plant to take root and give fruit. It is desirable that it has a fibrous structure.
  • Leaf condition. They should be light, with a developed leaf plate. The internodes need to be short.

Plants are not recommended to be planted immediately in the ground, if they are poorly hardened. In this case, the bushes are kept for several days in a cool room.

Hardening stages

Consider how to harden tomato seedlings after checking the sprouts for diseases. The hardening process consists of several stages.

Seed preparation

The first stage is the preparation of seeds for sowing. To do this, they are laid out on a small part of the fabric, placed in a bowl of water. To disinfect, add a few drops of Fitosporin and cover the seeds with another part of the tissue.

In the room, the seeds are kept in this condition for about a day, after which they are placed in the refrigerator. Cold and heat alternate no more than 2 days. Hardened seeds are also treated with manganese solution, and then planted in the ground. This processing process gives the effect of rapid ripening and yield of bushes.

Tatyana Orlova (candidate of agricultural sciences):

Hardening of swollen tomato seeds is carried out at variable temperatures for about 1.5-2 weeks. Only then will it give a result. The aim of this work is to obtain seedlings that are resistant to cold (but not frost-resistant!). Tomato plants grown from hardened seeds are capable of a relatively long time located at a low positive temperature (+ 6-8 degrees) in open ground.

One of the advantages of a hardened bush is the possibility of planting it several weeks earlier than an unhardened bush. The same goes for the first flower brush, which appears 3-4 days earlier. After sowing seeds hardened in this way, the sprouts germinate already on day 2.

Gardeners are advised to take tomato seeds, which:

  • survived the frost;
  • grew up in the fresh air;
  • were collected about 2 years ago.


After 3 weeks, the seeds are poured with hot water for 2 hours, after which they are placed in cold water for 3-5 minutes. After that, the seeds are ready for planting.

Tatyana Orlova (candidate of agricultural sciences):

Heat treatment of seeds is carried out to destroy viruses and pathogens of some fungal diseases that can persist on the seeds. Water temperature should be 45-50 degrees. To maintain this temperature for 2 hours, the seeds are placed in a thermos with hot water.

Gradually, the amount of watering is reduced. Initially, they are carried out using warm water, later its temperature is reduced. Tomato seedlings are watered once a week.

Hardening process

Stick to recommendations

The sprouts that have sprouted are planted in 11-14 days - they pick. After the appearance of the leaves, the hardening process begins, which is based on the following actions:

  • Lowering the temperature. In the room where the plant is located, lower the temperature from 30 ° C to 20 ° C. Over time, the plant is transferred to the balcony or exposed in the yard for about a couple of hours. In the process, observe the appearance of the leaves. Direct sunlight is contraindicated for sprouts.
  • Watering. It is undesirable to water the plant abundantly before it is taken out to the street. Leaving sprouts in the fresh air is allowed in the evening or in the morning for 3-4 hours. This lasts 3-5 days and is carried out just before the landing. Hardening of tomatoes occurs when the thermometer shows approximately 24 ° C of heat. At night, the temperature should be 7-11 ° C.
  • Safety from the wind. Sprouts should not be located in a draft. A strong wind can ruin the condition of the leaves, make the stem more vulnerable. It happens that gardeners use an extreme approach to stabbing, where low temperatures and windy weather are needed.

It is important to constantly monitor the condition of the plant, as when stabbing, the appearance worsens, after which the seedlings are brought back to a warm room.

Hardening at home

Hardening seedlings of young tomatoes can be implemented at home. In this case, it is necessary to observe the thermal regime and irrigation rules.

In order for the plant to feel temperature changes, it is necessary to take it out for 2-3 hours and place it near the window, after which it should again be brought into a warm room. This will harden the tomatoes as quickly and efficiently as possible.

Experts advise doing this gradually and each time increasing the time the plant stays in a cool room. An excellent solution is to leave a thermometer near the plant in order to monitor temperature changes as accurately as possible.

It is recommended to harden tomato seedlings at home 2-3 weeks before planting, after which it is planted in the ground and monitor its reaction. During hardening, the plant grows more slowly, but the advantage is a strong root and a powerful stem after the procedure. It is necessary to temper tomato seedlings, because this gives the plant immunity and tasty fruits.

Fertilizer application

With top dressing for sprouts, you need to be careful. If you use nitrogen fertilizer during the hardening of tomatoes, the plant's resistance to frost is reduced, it becomes sick, therefore, during the hardening of seedlings from tomatoes, you should not use this dressing.

Fertilizers that can be used in the hardening process:

  • A solution of potassium sulfate. It is taken in an amount of 60 g. 10 g of ammonium nitrate, 40 g of superphosphate are added to it. All components are dissolved in 10 l of water. The solution is used a couple of days before planting in the ground.
  • "Crystal" or "Kemira." They accelerate plant survival, help reduce the negative effects of pesticides. "Kemira" is saturated with trace elements: boron, molybdenum, manganese, iron, nitrogen. 2 tbsp. l fertilizers are dissolved in 20 liters of water, and for seedlings, the entire package is dissolved in 20 liters.
  • Liquid solution of double superphosphate. In total, 80 g will be needed, 30 g of potassium nitrate is put to it. Spraying occurs during the formation of ovaries.

Top dressing is applied both to the bush and to the root system. Spraying the leaves is especially popular, as through them the plant receives more beneficial elements. For the solution using settled or rain water.

Root dressing is also useful. It is introduced into the soil on the root system of the bush. Fertilizers of tomatoes in the open field are carried out with both mineral and organic solutions.

One option is to take 300 g of dry poultry manure, add 15 g of urea, 15 g of superphosphate and 13 g of potassium sulfate to it. Additionally, wood ash is added in an amount of 30 g. All components are mixed with 20 g of simple superphosphate and 0.3 g of manganese sulfate per 10 l of water.


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