Construction and operation of efficient greenhouses for a home garden

MODERN WRITER UDC 697.3 LBC 39.279 S 17

ISBN 978-985-16-3405-3.

The book describes in detail the designs of greenhouses, materials for them, and methods and ways of their construction. Also discussed are the issues of maintenance of greenhouses and hotbeds (lighting, heating, ventilation, soil preparation), and the cultivation of various vegetable, berry, and floral crops. Significant attention is paid to measures and means of plant protection against pests and diseases.

UDC 697.3 LBC 39.279

Protected by copyright law. Reproduction of the entire book or any part of it is prohibited without written permission from the publisher. Any attempts to violate the law will be prosecuted.

Growing organic vegetables in the countryside as early as possible is a dream of many city residents. But stable yields can only be obtained in structures that protect plants from changing weather conditions — in covers, hotbeds, and greenhouses.

According to historians, the first protected ground structures — the ancestors of modern hotbeds and greenhouses — appeared several hundred years ago, first in Holland, then in England and France. Today, no garden of ours can do without a plastic "palace" for vegetables. Apparently, every gardener wants to build a sturdy, convenient greenhouse on their plot that would suit them in all respects: simple to execute, inexpensive, reliable, and versatile.

A greenhouse is needed for growing strong, healthy transplants for spring planting. A greenhouse also helps fight insects and diseases, improves the nutritional quality of the crop, and allows producing more food from a smaller area. If in your climate the daytime temperature in winter ranges from 7 °C to 24 °C, and at night it does not drop below -3 °C, then plants can be grown in a greenhouse year-round without using any artificial heating. If in your climate the cold season lasts for 12 weeks with daytime temperatures from 4 °C to 16 °C, and nighttime temperatures do not fall below -10 °C, plants can be grown in a greenhouse all winter, but the cost of heating during the coldest weeks may make your project economically unfeasible. In these conditions, thanks to careful planning, you can have two harvests outside the normal vegetable growing period with minimal costs. First, grow crops in early spring and harvest so that you can plant new crops for the summer on time. Then proceed to growing an autumn crop. It is necessary for the plants to reach maximum fruit set and vegetative growth by the end of autumn. Then, during the cold months — December and January — only enough heat should be provided to protect the plants from freezing, maintaining the temperature above 0 °C. The plants will grow slowly during these cold months, but they will gradually ripen. In regions with a colder climate, year-round vegetable growing in greenhouses is in most cases impractical.

Advantages and possibilities of greenhouse cultivation

Greenhouses, like everything else in this world, have their pros and cons. When it is impossible to predict the summer weather, a greenhouse allows for earlier transplanting, extending the summer season, and harvesting for a longer time. When using greenhouses, the soil is protected, i.e., it is possible, regardless of external weather conditions, to maintain optimal temperature, air humidity, soil moisture in the greenhouse, cultivate plants using various agricultural techniques, and treat them with various growth stimulants growth stimulation and plant protection products.

Rules for design and placement of structures

If you decide to build a greenhouse on your plot, when designing this structure, make sure that its capabilities meet your needs: that the transplants will receive enough light, heat, oxygen, moisture, and necessary nutrients.

Greenhouses should be placed on a flat plot, entirely illuminated by the sun, if possible leaving enough free space that can be used for greenhouse expansion if necessary. Before starting to set up a greenhouse on your summer cottage plot, you need to orient it to the cardinal directions. In the Northern Hemisphere, face the ends of the greenhouse from east to west. This way, the plants will be able to derive the greatest benefit from sunlight.

The quality of natural ventilation depends on a large number of factors. These include:

• the "wind rose" of the area;
• the temperature difference inside and outside the greenhouse;
• the presence or absence of air filtration through grooves and gaps;
• the number and location of transoms and vents — they significantly improve the air exchange of the greenhouse with the environment compared to a door.

A greenhouse should be simple and economical. There are many types, kinds, and shapes of greenhouses; they can be covered with various materials, of which polyethylene film and glass are the most common.

Polyethylene film has advantages: it is lightweight, i.e., one can quickly install and remove the film itself, and it is also possible to quickly dismantle a wall or roof (for intensive ventilation, for example); the film does not break; it is relatively cheap; and film greenhouses do not require a foundation. However, there are also disadvantages — it is not durable. A simple film usually wears out in one season because polyethylene is very unstable to ultraviolet light. If a piece of film flutters in the wind, the wind will soon tear the entire greenhouse to shreds. Moreover, every year in spring, a film greenhouse practically has to be assembled anew. However, a greenhouse frame for film can be easily assembled from wooden slats, duralumin or plastic pipes, etc. Craftsmen have also invented many reliable ways of fastening the film to the frame.

A glass greenhouse is already a very serious structure. In essence, it is another little house for plants. It is heavy (a foundation is mandatory, otherwise the glass may crack). At the same time, transparent fencing possesses certain favorable optical properties: it transmits radiation in various wavelength ranges, provides the possibility of photosynthesis, and transfers solar energy to plants, which cannot be fully said about a film covering.

Now the advantages of glass greenhouses are becoming obvious. The soil in them is not covered with snow, freezes less, and thaws faster in the spring; the greenhouse can be forcefully heated from early spring (stoves, burners, electricity, etc.). Thanks to its long service life, the greenhouse can fully recoup the costs of its construction in 5—8 years. From an economic point of view, it is profitable to build a large greenhouse, since a larger harvest can be obtained from a larger area with proper agrotechnics.

Weigh all the arguments "for" and "against" and, if the former outweigh the latter in all respects, proceed to the construction of a greenhouse (or greenhouses, as it turns out for everyone). — = —х 9% т и

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What kind of greenhouses won't you see on household plots and summer cottages! Very often they are built by vegetable growers themselves — and sometimes very successfully.

You can also purchase ready-made industrial-manufactured greenhouses. But in this case, what should you look for when choosing and buying a greenhouse?

First of all, the greenhouse must be manufactured neatly and thoroughly. The strength and durability of the greenhouses save their owners from exhausting repair chores. It is best if the load-bearing greenhouse structures are made of cold-rolled galvanized steel. Frames should be mounted in the side walls and on the roof so that there are no cracks or gaps between the frames and the load-bearing structures — this will minimize heat losses.

Wooden frames suffer from dampness and fungi, and rot quickly. Therefore, they must be painted. In small-sized greenhouses, the frames are also made small so that it is convenient to work with glass. It is better to install stationary greenhouses on a foundation.

Either film or glass can be used as covering materials. Each of them has its own advantages and disadvantages.

The film, depending on the quality, will have to be changed every 2—4 years. Glass is more durable, but the glazing procedure is more labor-intensive, and the cost of glass is higher. Some vegetable growers arrange combined greenhouses: they cover the roofs with film and glaze the side walls.

Many vegetable growers prefer tunnel-type frame greenhouses, which are distinguished by the simplicity of construction and ease of operation. When building a film greenhouse, it is necessary to keep the following in mind: the length of the frame should not exceed the width of the film, otherwise the film will be used irrationally. As a greenhouse frame of the tunnel type, pipes bent in a certain way and coated with anti-corrosion paint are most often used. Recently, polymer pipes for greenhouse frames have also appeared on sale. These pipes are lightweight and good to work with, but they quickly deform under the influence of temperature fluctuations and winds.

A greenhouse covered with two layers of film separated by an air gap is interesting and rational in design. The first, outer, frame is made of metal pipes, and the second, inner, one is made of polymer materials. A thick and durable film is stretched over the outer frame, and a thin one over the inner one. Such a covering helps to prevent heat losses.

To reduce heat loss, a thrifty owner should choose a rational greenhouse design, use materials with low thermal capacity, and carefully seal all gaps (near doors, ventilation openings, between frames, etc.).

Good results are obtained by using panels made of new transparent polymer materials instead of traditional glass or film, installing special heat-reflecting screens that allow sunlight into the structure but keep heat from escaping, and using thermal insulation mats. Such mats are made not only of opaque materials but also of a special "foamed" film, which reduces penetration inside by only 4%.

Unfortunately, the peculiarities of our climate condemn us to growing many plants only in greenhouses. There is such a great variety of greenhouse designs that it is quite difficult to even list them. These are arched and tent, single and double-pitched, lean-to, film and glass, polycarbonate greenhouses, etc. In addition, there are different types of greenhouses. These can be winter gardens, orangeries, temporary, mobile greenhouses, hotbeds, and seedbeds. The most common option is rectangular greenhouses with a double-pitched roof. Such greenhouses provide plants with optimal lighting; they are simple and convenient to use.

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Fig. 1. Rectangular greenhouse with a double-pitched roof. General view

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Fig. 2. Construction of a spring greenhouse with a double-pitched roof made of hotbed frames with an area of 15 m²: 1 — posts; 2 — rafters; 3 — hotbed frames; 4 — support board for frame rest; 5 — drain; 6 — ridge beam; 7 — binding beam; 8 — board; 9 — visor made of roofing steel; 10 — shelving; 11 — support beam; 12 — shelf post; 13 — earth embankment; 14 — wall cladding

Fig. 3. Spring greenhouse of a lightweight design made of hotbed frames with an area of 14.8 m²

Round greenhouses or pavilions are not found very often on our plots. Actually, if you look at such greenhouses more closely, it turns out that they are not round at all. Depending on the design, the pavilions can be hexagonal, octagonal, or even dodecagonal. They are ideal for creating a flower orangery and look very elegant, although they are less practical. Air usually circulates poorly in a round greenhouse. Air exchange can be improved if, in addition to vents in the roof, at least one additional side window or air hole is provided. Another problem may be the arrangement of shelving for plants. In a round greenhouse, it is not so easy to place them in a way that achieves maximum effective use of the area.

Fig. 4. Round greenhouse (pavilion). General view

А И Не Fig. 5. Lean-to greenhouse

Another popular type is lean-to greenhouses. In this case, the greenhouse is attached to the house, saving on heating and materials. This is the most economical greenhouse option, which in some cases allows you to enter it without leaving the house. The lean-to greenhouse can have a separate entrance. Fig. 6. Lean-to greenhouse with a separate entrance

Quite often, you can find arched greenhouses. But the very shape of the structure implies that the greenhouse will either be covered with polyethylene film or have a polycarbonate covering.

Selection of design and planning of a greenhouse

Choosing the design of a greenhouse is a matter of taste; every owner is guided by their own considerations. Often we proceed from the possibilities that Fig. 7. we have — a patch of free space and a little money.

A good option is to buy a prefabricated greenhouse, as there are a great many of them for sale now, and they are made of a wide variety of materials. But most of the ready-made greenhouses available for sale have one significant drawback — they are designed and manufactured by people other than those who use them. And their design is adapted primarily for the convenience of their production, not their use.

If we build a greenhouse ourselves, we can design it so that it is convenient for both us and the plants. However, merely owning a greenhouse does not guarantee obtaining good vegetable harvests or the ability to admire the view of flowering plants in winter.

Types of greenhouses and temperature regime

Which type of greenhouse to choose is up to you. First, decide how you will use it: throughout the entire year or only during the spring-autumn period. This is the main point of reference you will follow from now on. Depending on this, you need to think about heating and all subsequent nuances.

The simplest type of greenhouse is an unheated hotbed. It has no additional heating, so it freezes in winter. Because the soil inside it warms up from the sun in the spring, such a hotbed allows extending the season of plant growth. The walls and roof protect the plants from bad weather, and the daytime temperature inside the hotbed is usually a few degrees higher than outside.

Most often, tomatoes are grown in an unheated hotbed; when it is not occupied by tomatoes, it can be used for growing:

• vegetable transplants;
• flower transplants;
• early vegetables.