In our latitudes, agriculture is limitedfour months a year. From its own garden during this time, it is usually possible to harvest without nitrates and other substances harmful to humans. In order to extend the period of growing the crop and be able to get organic vegetables, even in winter, you need to build a greenhouse on your site. Here we will talk about how to build a greenhouse with your own hands, what materials are used for them, how they are located, the ways of heating and lighting. From the school course of botany, everyone knows that the development of plants provides the process of photosynthesis, for which light, air, heat and moisture are needed. Therefore, in order to create conditions in the greenhouse, several factors should be considered at once: its appearance, volume, and translucent material, the organization of additional lighting, ventilation, air heating and irrigation.
Before considering how to build a greenhouse,should understand what they are. The greenhouses are divided into arched and hipped ones. The hip structure in its appearance resembles a small house, since it is formed by vertical walls and a gable, gable, flat or arched roof. Sometimes the opposite walls are slightly inclined inwards. Arched the same design in its appearance resembles a tunnel of transparent material. Its construction consists of parallel arcs connected to each other, and flat walls from the ends. The frame is assembled from an aluminum or steel corner using screw connections or welding. The steel structure is primed and painted or zinced to protect against corrosion, and the aluminum profile need not be protected. The most convenient height for greenhouses is 2-2.5 meters, and width 2.5-3.5 meters. Although you can use absolutely any size. This width allows you to make three beds with two paths between them instead of two side paths with one central path. And although the useful area is slightly reduced, but it is much more convenient to work in such a greenhouse. The width of the bed is mainly dependent on the crops grown. In this case, consider that the optimal distance from the plant to the edge of the bed, especially if it is near the walls, should be 30-40 centimeters. The length of the structure can be varied, since the greenhouse is assembled from separate sections. In the end walls are provided hinged, swinging or sliding doors, which are needed not only for maintenance, but also for ventilation of the greenhouse. In addition, for airing arrange folding or swivel skate transom. In standard tent hothouses, they are usually up to three pieces on each side of the ridge, but any number can be set if desired. The transparent coating of the greenhouse should not only possess the optical properties of a certain limit, but also be strong enough, and also withstand temperature changes from -20 to + 60 ° C. The task of a translucent coating is to transmit radiation in the PHA range, which provides photosynthesis. In addition, it must pass at least seventy percent of infrared and near and far ultraviolet radiation, which transmit solar energy to plants. As a translucent coating, glass or a film - polyethylene or polyvinyl chloride - is used. In recent years, plastics have been used for the construction of greenhouses. For those who are interested in how to build a greenhouse of polycarbonate with their own hands, it will be important that today a relatively new material - cellular polycarbonate has become widespread. All these materials are characterized by their translucency, which shows the ratio of transmitted light to the total radiation energy. All of the above materials miss most of the FAS radiation, as well as the near ultraviolet range. Infrared and far ultraviolet range, they miss enough, and they should be compensated artificially. The lack of heat wave radiation of the infrared range is compensated by heating in the greenhouse air heat devices, and compensation for long-range ultraviolet radiation is provided by special ultraviolet lamps. To seal the greenhouse, glazing is glued with a rubber profile, which guarantees a stable necessary microclimate. These rubber seals provide ozone, moisture and light fastness. Today, various manufacturers produce prefabricated greenhouses. Some of them use guides for guides with latching. They make it possible to take a sheet of glass in a couple of minutes. But it is much safer and more convenient to use a polycarbonate as a translucent coating. It is not only stronger and lighter than glass, but also less fragile. Particularly convenient cellular polycarbonate for the construction of an arched greenhouse. In addition to the fact that it looks more attractive due to it, such a greenhouse with a similar base area has a larger volume than a hipped roof. And this means that there is more air in it. Previously, in the arched greenhouses, only the end walls were glazed, and the spaces between arched arches were covered with a film, which was removed for the winter. The windows were provided above the door or next to it in the end surfaces. Polycarbonate, which easily bends, allows you to close the entire frame, and in the dismantling for the winter will not be necessary. In addition, if there is a need for intensive ventilation or the drying out of the greenhouse, it is possible, on the one hand, to release plastic sheets without any damage to the entire construction of the greenhouse.
Location of the greenhouse
To place the greenhouse on the site should be independing on how you intend to use it. If it will be used all year round, then it is better to orient it from west to east. If it is supposed that the ground will rest in winter, the greenhouse should be located from the south to the north - this will reduce the danger of summer plant burns. It is convenient to have a tent greenhouse with a saddle roof so that it adjoins the south wall of the house from the south side. This will significantly reduce the amount of energy needed for its heating. Optimal for our region, the angle of inclination of the roof to the horizon line is 25-30 °. To avoid the appearance between the wall of the house and the greenhouse of mold and dampness, it is necessary to make a waterproofing between them from the pergamina or roofing material. When year-round use in a tent hothouse it is better to make long walls inclined inward by 10-15 °. This will make it possible to accumulate solar energy in wintertime. In this case, it is necessary to take into account the cold winds and provide protection against them, because they can increase energy losses by one and a half. To do this, it is best to plant a hedge on the leeward side, the distance to which should be 5-10 times the height of the greenhouse. With frequent north winds it is allowed to install a greenhouse next to some structure, because the shadow from it will not be too big in this direction. The place where you intend to install a greenhouse should be flat. If there is no such place on the site, it will be necessary to equip the bulk platform. Under the glass greenhouse, it is better to make a strip foundation with metal fittings with the location of the sole at a depth of up to thirty centimeters. Such a sturdy and rigid construction will make it possible to exclude distortions and cracks in the foundation, which can lead to skewing of the carcass, and then to cracking of the glass, respectively. If the groundwater lies at a depth of less than 0.6 m, it is necessary to provide a drainage system. Because excess moisture can lead to swelling of the soil, which will worsen the development of plants.
Water supply, heating and ventilation of greenhouses
With the help of convection can be leveled in the greenhousetemperature and mix air. But it does not provide fresh air, which is simply necessary for plants in the dark for the breathing process. Everyone knows that plants generally excrete oxygen during the day, and absorb at night. The microclimate of the greenhouse differs from the natural one in that the temperature regime and ventilation are not only selected, but also maintained so as to provide optimal conditions for the grown plants. Relative air humidity in the greenhouse should be about 70%, and the temperature is selected from the account of specific plants, so that they do not overheat and dry up. If there is no heating in the greenhouse, the temperature depends on the heat exchange conditions. That is why the volume of the greenhouse is of great importance. It also affects the rate of change in temperature after sunrise or sunset. To simplify the maintenance of the system, this indicator must be associated with the climatic conditions of the terrain. In order for plants to develop normally, so that they do not rot and do not "burn", especially in summer, the humidity and temperature in the greenhouse are regulated by ventilation and ventilation. The coefficient of air exchange in practice with a cloudless sky in summer should be a multiple of fifty. For ventilation even small greenhouses will need several fairly powerful instruments. To reduce costs, ventilation can be combined with ventilation. Due to the well-planned organization of ventilation, ventilation can be completely eliminated. Air exchange with ventilation can be controlled by a clock or a thermostat. Airing, however, is more difficult to control - it will be necessary to sit outside the greenhouse for days, closing the windows and transoms. Left unattended, the greenhouse is difficult to protect from bad weather - rain, wind, hail. Ventilation should provide the necessary air exchange. Most often with its help provide an inflow into the lower part of the greenhouse of atmospheric air, which rises up, warmed up, and exits through the transoms in the roof. It should be remembered that this process needs to cover the entire volume of the greenhouse, leaving no stagnant air anywhere. In practice, use the organization of air exchange with the help of two equivalent schemes:
- the flow of air and drawing it through the roof from the opposite sides of the greenhouse;
- inflow from below - in the middle or along the edges, and the hood through the roof, also along the edges or in the middle.
The inflow of fresh air is carried out byairing, opening for this ridge transoms and doors. In the hothouse greenhouses, additional windows in the walls are provided for this. If desired, the ventilation of the greenhouse can be automated by installing a special mechanism with a working fluid that does not freeze. If the temperature in the greenhouse rises, the liquid warms up, expands and pushes the rod, which raises the window. And vice versa. Ventilation dries air in the greenhouse. Therefore, it is necessary to provide for its humidification to maintain the necessary humidity. But it should also be borne in mind that in a damp environment, plant diseases develop more rapidly, and if they are too dry, they die. The issue of humidity is solved by creating a mini-irrigation system that can provide the necessary watering in automatic or semi-automatic mode. These systems are controlled by special sensors. If there is a water supply in the greenhouse, the labor intensity of the work will be significantly reduced. To create a water pipe is better with the use of plastic pipes, which are provided with thermal insulation. For convenience and safety, they are laid in the ground with the exit already in the greenhouse itself. Growing plants in a greenhouse at outdoor temperatures below 5 ° C is possible only with mandatory heating of air, because the heat accumulated by daytime solar energy is not enough to maintain the microclimate in the greenhouse at night to ensure and preserve the life of plants. It must also be taken into account that the sun does not shine every day. To ensure the appropriate temperature, there are different types of heat sources, but selecting them, it should be remembered that the energy dissipation of the greenhouse is much higher than the residential house. Therefore, year-round greenhouses should be provided with better sealing than seasonal ones. The electrification of the greenhouse will make it easier for you to maintain it. In addition, it will provide an opportunity to use additional equipment, for example, ultraviolet lamps for planting plants. As additional heat sources, it is possible to use pipes that are located along the perimeter of the greenhouse along the walls. Sprinkler irrigation system can be made mobile. Between the spray nozzles, the optimum pitch is 1.6 m. Considering all the above rules of construction and equipment of greenhouses, you can not leave your site all year round in the summer.