The seedling method of growing vegetables and other garden crops is associated with our climatic conditions. In the vast majority of regions of the Russian Federation, the frost-free period with an average daily temperature of + 10 ... + 15 ° C is 110-140 days a year, which is significantly less than that required by most vegetable crops with a long growing season (from 130 to 200 or more days). Sowing and planting plants in open ground is possible from March-April - a period of a fairly high arrival of solar radiation. But the frost-free period begins in the regions from May 25 to June 10-15. Weather conditions are created that limit the normal development of plants. In such conditions, the greenhouse period of 30-60 days is a good time saver for heat-loving crops that do not have a short summer to form and ripen the crop in open ground.
Why is it necessary to harden seedlings?
Seedlings in our apartments and greenhouses are grown under artificially created conditions at optimal temperatures + 18 ... + 30 ° С, and a sharp change in temperature and humidity conditions when planting them in open ground negatively affects the state of seedlings. In addition, any intervention in the natural environment of plants, including transplantation, leads to the disease. When transplanting, the root system suffers. A period is needed to restore the normal process of supplying water to the organs of the aerial mass of plants.
During this recovery period, the environment must have a gentle effect on young seedlings. An inactive root system, a mismatch between the intensity of illumination and temperature conditions leads to a halt in metabolic growth processes in plants. To reduce the period of getting used to the new environment, which will contribute to a faster restoration of seedlings, it is necessary to gradually accustom or prepare seedlings for new conditions. This is the main essence of hardening seedlings.
How to conduct hardening seedlings?
Through seedlings, you can grow almost all vegetable crops, the development period of which is longer than the warm season of the region, and if you want to get an earlier crop of open field vegetables. Such crops include tomatoes, sweet and bitter peppers, eggplant, cucumbers, squash squash, pumpkin, watermelon, melon, all kinds of cabbage and other crops.
In order to get a healthy, normally developed seedling, hardening should be carried out the entire period of its growth and development indoors (in a greenhouse, hotbeds, at home on a windowsill, etc.) until planting in open ground. Seedlings are gradually taught to live in open ground.
The first hardening of seedlings is carried out 2-4 days after germination. Within 4-7 days, the air temperature in the room is reduced from + 17 ... + 25 ° С to + 8 ... + 16 ° С during the day and from + 10 ... + 15 ° С to + 7 ... + 12 ° С at night depending on the culture (table. 1 and table. 2), which counteracts the extension of seedlings.
A further decrease or on hot days a sharp increase in temperature will slow down the development of seedlings and their disease. Starting from 2 weeks of age, the temperature regime of seedlings up to the start of hardening of seedlings is maintained in a given range, gradually tightening environmental conditions.
On sunny hot days, the room is ventilated without drafts. Open windows or transoms from 5-15 minutes a day to 2-4 hours. During the greenhouse growing season, it is necessary to constantly monitor not only the temperature of the air, but also the soil. A pampered root system, once in open ground, will not withstand temperature extremes and can become sick, leading to the death of the plant.
|Name of culture||Air temperature ° C|
|4-7 days from seedling emergence||From day 8 from hardening of seedlings to hardening of seedlings|
|In the afternoon||At night||in the afternoon||in the afternoon||at night|
|Sweet and bitter pepper||14-17||8-10||18-20||25-27||11-13|
|Early White Cabbage||8-10||7-9||13-15||15-17||7-9|
|Name of culture||Soil temperature, ° С|
|12-15 days from seedling emergence||From day 16 from hardening of seedlings to hardening of seedlings|
|in the afternoon||at night||in the afternoon||at night|
|Sweet and bitter pepper||20-24||17-18||20-22||15-16|
|Early White Cabbage||15-17||11-12||14-16||10-11|
Seedlings of all seedlings in the early days can not stand direct sunlight and can get a severe burn of young leaves. Therefore, from the time of seedlings, the first 3-4 days, the seedlings are shaded, leaving in the sun for 15-20 minutes a day from 10 to 11 or from 14 to 15 hours. The time of solar illumination is gradually increasing and by 2 weeks of age the seedlings can be left open for the whole day.
The need for additional seedlings
In the winter-spring period, the seedlings are clearly not enough in the intensity of natural light and plants need a long daylighting. The exposure time for tomatoes is 14-16 hours a day. For eggplant and peppers up to the phase of 4 real leaves, the light period lasts 14-16 hours, and then 10-12 hours. For cruciferous, the irradiation period ranges from 10-12 hours. Pumpkin plants belong to short-day plants and do not need additional illumination.
When growing in a greenhouse seedlings of several crops with different lighting periods, use covering material that does not transmit light rays. When growing seedlings of several crops at room conditions with different lengths of daylight, after 10-12 hours of light time, containers with plants are taken out into a darker and cooler room, and the next day they are returned to their place.
Hardening seedlings before planting in open ground
Regardless of the place of cultivation (at home, a greenhouse, a greenhouse, under temporary shelter from a film or spunbond), seedlings must be pre-planted hardened. For 1-2 weeks (no more) before the seedlings are planted in the soil, the air temperature is reduced at night to + 12 ... + 14 ° C for tomatoes, eggplant, sweet pepper, pumpkin, and for more cold-resistant (cabbage, lettuce) - to + 6 ... + 8 ° С.
If you increase the period of active hardening to 3 or more weeks, and even with a further decrease in temperature, the plant inhibits growth, which subsequently reduces the crop yield, sometimes up to 30%.
Lowering the temperature 3-5 days before disembarkation is brought to the level of the ambient temperature of the open space. For this, seedlings grown indoors are taken out to a closed balcony and left there around the clock. It is better to close the window for the night so that there is no sharp night cooling. If seedlings were grown in a greenhouse or transoms are raised in a greenhouse, so that the temperature gradually equals the street temperature.
Simultaneously with the hardening of the aerial parts, the root system of seedlings is accustomed to lower and more severe conditions. Together with lowering the air temperature, they reduce the amount of watering. The irrigation rate is not changed, only the intervals between irrigation are increased. A longer dry period helps to dry the soil coma. The soil remains moist in the zone of the root system, but is dried in the upper part.
This mode stops the growth of seedlings. It becomes more “stocky”, the root system grows intensively, the leaf apparatus develops, in cabbage the leaves are covered with a waxy coating. It is very important not to dry the soil during this period. The falling of buds will begin, the turgor of leaves will decrease to a painful state. In general, plant viability will decrease.
1-2 days before planting, quench dressing is carried out, providing plants with basic nutrition. Some gardeners carry out this procedure 10-12 days after a dive. You can feed the plants with a solution of ammonium nitrate, superphosphate and potassium sulfate (10, 40 and 60 g per 10 liters of water, respectively) or nitrofosk 60-70 g / 10 l of water. For feeding, you can use Kemir, crystallon or other mineral fertilizers containing nitrogen, phosphorus and potassium. Top dressing will reduce the survival period and increase the number of plants that have taken root to 100%.
The last days of seedlings should be around the clock in an open space under a canopy or on an open balcony. If there is a risk of frost, the seedlings are covered with spanbond or other integumentary tissue at night. Shelter film less comfortable for plants.
Well-seasoned and well-fed seedlings when transplanted to field conditions will be much easier to tolerate a stressful situation and will actively continue their further development. With poor-quality preparation for transplanting, seedlings inhibit development for 5-10 days or more.