Lighting for greenhouses - options, do-it-yourself arrangement

Nowadays, many gardeners who love to eat food from their gardens are thinking about building greenhouses. Russians liked fruits and vegetables that previously grew only in the southern regions, so many decide to create a greenhouse to diversify their diet.

After the greenhouse itself is ready, the beds have been created, watering and heating of crops has been thought out, you need to think about lighting. In summer there is enough sunlight and the plants grow well. When there is less sunlight, it is important to properly organize the lighting in the greenhouse and study the pros and cons of different types of lamps.

Greenhouse lighting

Lighting ranges

Daytime sunlight contains all the colors visible to the human eye and is itself white. This lighting is ideal for plant development.

Some spectrum ranges have a positive effect on plant growth

Artificial lighting affects plants in different ways:

light in the range from 280 to 320 nm is harmful to vegetation;
320-400 nm - light has a regulatory function, very little is required;
400-500 nm - blue light, it is necessary during the vegetative growth of the plant;
500-600 nm - green, most useful for photosynthesis of lower dense leaves;
600-700 nm - red lighting is extremely important for photosynthesis, especially during the flowering period;
700-750 nm - “far” red light, plays a regulatory role, is needed in small quantities;
in the spectral range of 1200-1600 nm, the process of biochemical thermal reactions is accelerated.

Artificial lighting systems for greenhouses

At different periods of their development, plants respond well to different ranges of the light spectrum. Seedlings prefer “blue” light; during fruiting, “red” plays a more important role. But this does not mean that light emission of other colors becomes unnecessary. The lack of full spectrum in artificial lighting causes incomplete taste of the harvested crop. Until lamps that completely imitate solar white light have been invented, lamps with different spectrums of light emission have to be combined in the same greenhouse.

Dependence of photosynthesis efficiency on light wavelength

Prices for phytolamps for plants

phytolamps

Types of greenhouse lamps

You can illuminate a greenhouse with several types of lamps:

incandescent;
luminescent;
sodium;
mercury;
metal halide;
LED;
infrared.

Incandescent lamps

They illuminate the greenhouse room well and also warm the air a little. Their disadvantage is that they consume a lot of electricity and have low efficiency. Their incandescent spectrum is 600 nanometers. If plants are overheated, they will get leaf burns. Burns occur due to excess infrared, orange and red light. Also, when overheated, the stems become unnaturally stretched, and the foliage becomes deformed, becoming small and limp.

Fluorescent lamps

The color spectrum of fluorescent light bulbs works well for greenhouse crops. They last a long time and their cost is low. These lamps work in the same way as energy-saving lighting fixtures, but can illuminate a larger area. These are fluorescent lamps: they illuminate both seedlings and grown plants. For their installation, metal boxes are used, as well as special lighting fixtures made of plastic.

Sodium lamps

These are economical light bulbs that operate under high pressure. Previously, their color spectrum was only red-orange, close to the rays of the sun. There were few blue rays from sodium lamps. In this regard, a modification was made, as a result of which lamps with a blue spectrum of light rays appeared.

On a note!

Despite improvements, sodium-based lamps attract harmful insects. This makes them difficult to use in greenhouses and greenhouses.

Mercury vapor lamps

Mercury lamps provide near-ultraviolet light that is beneficial for crops. These are compact and bright light sources. Ultraviolet light helps to activate photosynthesis processes, but it should not be abused. The use of mercury lamps is possible provided they are combined with natural lighting. They are used when the fruits begin to ripen. To work with mercury, a stable voltage in the electrical network is required. In this case, differences of no more than 5% are allowed.

Metal halide lamps

The light spectrum of metal halide lamps is well suited for plants. These light sources are compact but difficult to install. After their service life has expired, they must be recycled and not thrown into the general garbage chute. Despite this specificity, metal halide lamps have a high level of light transmission. They are ideal as daytime lighting sources if the mains voltage is not subject to strong surges. With the slightest change in voltage, the color spectrum of these lamps will change. If the light source is turned off, a short time must pass before operation is restored.

Not every gardener can afford to use metal halide lamps due to their high price and sensitivity to mains voltage.

LEDs and their applications

LED lamps are so diverse that you can choose any color spectrum by making a combination of several lamps. Gardeners select different colors for each plant crop. LEDs last a long time and consume minimal electricity. They are placed at different heights, adjusting the light intensity. Light bulbs that produce blue colors are suitable for seedlings. For fruit ripening, rays of the red and orange spectrum are used. It is necessary to take into account the sensitivity of LEDs to voltage changes and monitor the condition of the electrical wiring. If the electrical wiring is in good condition, they will justify their cost in the first season of use.

Ultraviolet lamps

They work in the same way as fluorescent lighting sources. Ultraviolet radiation appears in the flask container. It appears due to the reaction between mercury and an electromagnetic discharge. The gas discharge tube is made of uvila or quartz glass, which transmits UV radiation. Uviol glass is considered safe because it produces less ozone. The composition of glass used to make UV lamps varies. This allows you to create light sources that operate in a specific color range.

Infrared heaters

They are used to heat plants. Infrared light sources are classified as energy-saving systems. They create a favorable microclimate in the greenhouse. Thanks to him, cultures develop no worse than in the natural environment. The luminaires are equipped with a manual or automatic control function that allows you to control and change the indoor air temperature. Convector heaters can only heat air.

Information!

Infrared lamps first give off heat to plants and the ground and only then heat the air.

Amount of light

Each plant requires a certain amount of light to grow and develop. But there is also a universal rule - plants that bear fruit require more sun than those that produce edible leaves.

Signs of lack of light

Signs of excess light

The requirements for photoperiodicity also differ. Typically, tropical plants need short daylight hours, while northern plants need long ones.

PAR for different plants and vegetables

If you look at popular crops, short-day crops include:

eggplant;
zucchini;
pepper;
tomatoes;
beans.

It is enough for them to be in the light for 8-10 hours.

Plants need light as a source of energy for photosynthesis and accumulation of organic matter.

The following crops will require long daylight hours (more than 12 hours):

garlic;
cucumbers;
onion;
cabbage;
roots.

The behavior of some plants depending on the length of daylight hours

Note! If daylight hours have become less than eight hours, additional lighting of the greenhouse becomes mandatory.

Should the economy be economical?

The fact that LED lights are beneficial for plants is an indisputable fact. But the price! For plant growers, the timing of product sales plays a major role. The use of LED lamps accelerates the development and ripening of plants by 2 weeks. And in two weeks the price of crop products can fall 2-3 times.

The energy consumption of LED lamps is 10 times less compared to conventional lamps. And compared to sodium lamps it is 3-4 times.

The continuous operation time of modern LEDs reaches from 50,000 to 100,000 hours of continuous operation. If you turn on such a lamp for about 10 hours a day, then its operation will last 5000-10000 days. Or 10000:365=13.5-27 years!

And this is not a fact that the lamp will burn out and fail. Over time, the glow power simply decreases.

LED lighting in greenhouses accelerates the development and ripening of plants by 2 weeks. And in two weeks the price of crop products can fall 2-3 times.

The energy consumption of LED lamps is 10 times less compared to conventional lamps. And compared to sodium lamps it is 3-4 times.

Light in the greenhouse

Natural light is ideal. In order to provide them with the maximum amount of plants, the greenhouse should initially be installed taking into account the location to the cardinal points. The greatest amount of light enters the greenhouse in the north-south direction. The design of the greenhouse itself plays a significant role.

Correct location of the greenhouse on the site

Illumination of greenhouses of various designs

If one of the walls of the greenhouse is in contact with the building, it (the wall) is made reflective using mirrors or foil or painted with glossy white paint.

How to manage this?

There is no point in using constant 24/7 lighting in a greenhouse. Why?

Firstly, this regime is harmful to most plants. They require not only light day, but also dark night.

Secondly, for high-quality lighting of the greenhouse you will need more powerful lamps than those that burn in the evenings at home. This means that they will consume quite a lot of electricity.

Consequently, the lamps will have to be turned on in the morning, turned off during the day, turned on again in the evening - and turned off at night. How to achieve this?

Controlling greenhouse lighting can be based on one of two principles. The light comes on and goes off according to a timer, at a certain time, or it reacts to signals from light sensors. Both systems have their advantages and disadvantages.
The bad thing about the timer is that it doesn't respond to real light changes. The light will be stable in the morning and evening. But if the day is cloudy, the plants will be dark during the day.
There is also a catch with the light sensor: it tries to turn on the lamps all night, and greenhouse plants do not need round-the-clock light.
The ideal option would be a system that has two control options at once. Timer - completely turns off the lighting at night so that the plants have a full dark period in the day. And the light sensor allows you to turn it on at odd times during the day, if, for example, there are clouds. But this is complicated and expensive, so it’s probably easier to just use a timer.

Artificial lighting

Thanks to technological progress, modern gardeners provide greenhouse plants with light both at night and in winter, while artificial lighting:

improves plant growth (growing exclusively with natural light significantly reduces productivity);
allows you to receive products in a shorter time and at a time when demand for it is highest;
helps to grow heat-loving crops that are not found in the local climate;
reduces the final cost of vegetables by 15% by increasing yield.

Artificial greenhouse lighting

Types of light modes for a greenhouse

The light flux comes in the quantity strictly required for the plant. The light energy density ranges from 400-1000 mmol/m2. Lighting can be made continuous by using special relays that automatically turn on the lamps when the intensity of sunlight decreases.
Night lighting is required when daylight hours are artificially extended. Energy density decreases to 5-10 mmol/m2. The lamps are turned on only from time to time. With this approach, you can either slow down or speed up the flowering time. Acceleration of growth is achieved by frequently turning on a weak color every half hour. During the time the lights are turned off, the plants do not have time to “fall asleep” and grow in the same way as with constant light. Incandescent lamps with a reflector can handle this task.

Incandescent reflector mirror lamp

If none of the regimes are followed, you cannot expect quality products. Vegetables will bloom without bearing fruit, and vegetative plants will not even reach flowering.

Short

Additional lighting , switched on automatically, is necessary for those greenhouses that are used year-round. A winter day is so short that it is not easy to “squeeze” at least some benefit out of it for plants.
Light is also very important when growing early crops. If you are trying to make your plantings feel like it’s already summer, even though it’s early spring behind the glass of the greenhouse, then heat and moisture will not be enough. With short days, they won’t “believe” you and may refuse to bloom.
And those who are trying to harvest exotic species in Siberia that require long daylight hours for development also need lighting in the greenhouse!
If your budget is tight, don't try to squeeze lighting into it. Better think about the reliability of the design, and invest as much as possible in it.
Automatic lighting, like any other automation, is not required for light temporary structures such as greenhouses.
Perhaps you should refrain from innovation if you are already getting excellent harvests every year. Remember the saying: “Don’t fix what isn’t broken.”

Ekaterina KHOZYAINOVA, Tyumen Special issue of the city of Fazenda - “Future harvest 2015”

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Greenhouse electrification

Step 1. First you need to draw a detailed plan indicating the locations of light sources, switches and wire routes.

How to properly place plant lighting

This greenhouse lighting diagram shows power outlets at both ends, four HID lights above the growing areas, fluorescent lights above the aisle for general lighting, and outlets for heat mats and power tools

Step 2. The required footage of wires, the number of junction boxes, lamps, switches and auxiliary materials are calculated.

Table of recommended lighting power relative to greenhouse area

Advice! Wires should be preferred with a cross-section of at least 2x2 cm. To facilitate future wiring repairs, you can use wires of different colors. One color will indicate phase, the other will indicate zero.

Step 3. Everything you need is purchased (with a small reserve). All elements must be moisture resistant.

Step 4. The wire is removed from the distribution panel located in the building. An automatic greenhouse switch is installed in the common meter of a residential building.

Distribution panel

Step 5. Electrical wiring to the greenhouse is carried out.

Example of electrical circuit diagram in a greenhouse

Method A - underground:

a trench is dug at least 80 cm deep; it should not intersect with the drainage;
the wire with a protective screen must be covered with tiles in order to protect it in the future when digging up the earth.

Underground cable laying diagram

Laying electrical cable in a trench

Method B - by air: