When growing various crops year-round, lighting in winter greenhouses is essential. In autumn and winter, daylight hours are shorter than in summer. Plants require additional light sources. Without sufficient light, they will slow down and die. When setting up greenhouse lighting, it's important to carefully calculate the required amount and familiarize yourself with the different types of lamps.
Light and its importance for plants
Without enough daylight in winter and fall, crops begin to wither and become diseased. Photosynthesis is the key to plant survival and health. Complete photosynthesis is impossible without light. When plants produce chlorophyll, they fully absorb carbon dioxide, which is essential for nutrition. The formation of organic matter in greenhouse crops is impossible without sunlight and artificial light.
Signs of insufficient lighting:
- change in the shape of plants (for example, unnatural elongation of cuttings and stems);
- their slow growth;
- lack of flowering;
- decline in crop yields;
- the lower leaves turn yellow.
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Plants respond best to red and blue light. When lighting a greenhouse in winter, ensure that crops are not deprived of natural light. Also, avoid using only one spectrum of light unless you're growing flowers. This is beneficial for flowers, as it makes their colors richer and more vibrant.
Light rays affect greenhouse crops differently. Blue light stimulates photosynthesis, while orange and red light enhance flowering. These colors should be used sparingly, otherwise the plants will die. Ultraviolet radiation promotes the formation of vitamins, making seedlings more resilient to winter cold.
When selecting greenhouse lamps, they should be of different colors. When installing the equipment, it's important to adhere to lighting standards, in accordance with regional requirements and crop characteristics.
Specifics of greenhouse lighting in winter
If crops receive limited light, less than 10 hours per day, their growth may stop. The average daily light duration in a greenhouse in winter should be between 12 and 16 hours. Depending on the time of day, two methods are used for illumination:
- lamps (during the day, as additional lighting);
- photoperiodic lighting (at night).
Night illumination
Using lighting fixtures 24/7 isn't beneficial for crops. They require about six hours of complete darkness to rest. Some vegetables, berries, and other plants require specific lighting conditions.
Cucumbers don't tolerate periods of inactivity between different types of light. When growing cucumbers, natural and artificial lighting should alternate evenly. Once the first cucumber seedlings emerge, they need regular supplemental lighting. Onions and greens require supplemental lighting only during the initial growth stage. Strawberries require supplemental lighting during both day and night.
Lighting time
The amount of light depends on the sun-loving nature of the crop. Tomatoes, cucumbers, lettuce, and bell peppers require 10 hours or more of daylight.
There are short-day plants. It is the short daylight hours that trigger their flowering. When daylight hours become longer, their vegetative period ends and they begin to develop as usual. Long-day plants flower when daylight hours exceed 13 hours. If the daylight hours are shorter, their fruits will become small or stop appearing altogether.
There are crops for which daylight hours are irrelevant. They grow regardless, as long as there's not too little light. If there's too little, the plants will die.
Types of greenhouse lamps
There are several types of lamps that can be used to illuminate a greenhouse:
- incandescent;
- fluorescent;
- sodium;
- mercury;
- metallohalogen;
- LED;
- infrared.
Incandescent lamps
They provide good illumination of the greenhouse and also provide slight warmth. Their drawback is that they consume a lot of electricity and have low efficiency. Their incandescent spectrum is 600 nanometers. If plants are overheated, their foliage will burn. This burn is caused by an excess of infrared, orange, and red light. Overheating also causes unnatural stem elongation, and foliage becomes deformed, becoming small and limp.
Fluorescent lamps
The color spectrum of fluorescent bulbs works well for greenhouse crops. They last a long time and are inexpensive. These bulbs operate similarly to energy-saving lighting fixtures but can illuminate a larger area. These are daylight bulbs: they illuminate both seedlings and mature plants. They are installed in metal boxes and special plastic lighting fixtures.
Sodium lamps
These are energy-efficient light bulbs that operate under high pressure. Previously, their color spectrum was only red-orange, similar to sunlight. Sodium lamps had little blue light. Therefore, an improvement was made, resulting in lamps with a blue spectrum of light.
Mercury lamps
Mercury lamps provide near-ultraviolet light, beneficial for crops. They are compact and bright light sources. Ultraviolet light stimulates photosynthesis, but it should not be overused. Mercury lamps can be used when combined with natural light. They are used when fruits begin to ripen. Working with mercury requires a stable power supply, with fluctuations of no more than 5%.
Metal halide lamps
The light spectrum of metal halide lamps is well suited for plants. These light sources are compact but difficult to install. At the end of their lifespan, they should be recycled rather than thrown into the general trash chute. Despite this, metal halide lamps have a high light transmission rate. They are ideal as daylight sources if the power supply is not subject to significant fluctuations. The color spectrum of these lamps will change with the slightest voltage fluctuation. When the light source is disconnected, it will take a short time for it to resume operation.
Not every gardener can afford to use metal halide lamps due to their high price and sensitivity to electrical voltage.
LEDs and their applications
LED lamps are so versatile that you can create any color spectrum by combining several fixtures. Gardeners select different colors for each crop. LEDs last a long time and consume minimal energy. They can be placed at different heights, allowing for adjustable light intensity. Blue bulbs are suitable for seedlings. Red and orange beams are used for fruit ripening. It's important to consider the sensitivity of LEDs to voltage fluctuations and monitor the electrical wiring. If the wiring is in good condition, the LEDs will pay for themselves within the first season of use.
Ultraviolet lamps
They work in the same way as fluorescent light sources. Ultraviolet radiation is generated in the bulb. This is produced by a reaction between mercury and an electromagnetic discharge. The gas discharge tube is made of uviolate or quartz glass, which transmits UV radiation. Uvioleate glass is considered safe because it produces less ozone. The glass composition used to make UV lamps varies, allowing light sources to be created that operate within a specific color range.
Infrared heaters
They are used to heat plants. Infrared light sources are considered energy-saving systems. They create a favorable microclimate in the greenhouse, allowing crops to grow just as well as in the natural environment. The lamps are equipped with manual or automatic control, allowing you to monitor and adjust the air temperature inside the room. Convector heaters can only heat the air.
What lighting is used for different greenhouses?
Polycarbonate greenhouses are common in summer cottages and private properties. Industrial greenhouse structures are made of glass. Different types of greenhouses use different light sources, depending on the crops grown there.
You may be interested in:Lighting of polycarbonate structures
They build from polycarbonate Small greenhouses for growing vegetables, fruits, and berries. The good light transmission of polycarbonate sheets eliminates the need for additional light sources in the summer. In the fall, winter, and early spring, it's important to learn how to properly combine natural and artificial lighting. With proper calculations, you can profit from every square meter of your greenhouse or hothouse.
The following are used as artificial light sources:
- fluorescent lamps;
- LEDs;
- ultraviolet.
Industrial greenhouse complexes
Incandescent lamps are not used in industrial greenhouses. The following are used for lighting industrial greenhouse complexes:
- sodium lamps;
- metal halide lamps.
As noted, the light spectrum of sodium lamps is similar to sunlight. Despite the risk of attracting pests, sodium lamps are energy-efficient and can be used for a long time. Growers value sodium lamps for their red and blue spectra, which are essential for all types of crops.
The broad emission spectrum of metal halide lamps also allows them to be used on an industrial scale. The high price doesn't deter professional growers, as metal halide lamps are compact and offer a broad spectrum of light.
How different plants are illuminated
Some gardeners consider cucumbers to be an easy-to-grow crop, but this isn't entirely true. If signs of insufficient light appear, consider installing additional lighting. Cucumbers don't like long gaps between day and night lighting. This can slow their growth and result in small, wilted fruits. Light relays can be used to automatically illuminate cucumbers at any time of day.
Cucumbers Cucumbers should be continuously illuminated for 10-12 hours, followed by a break of about 6 hours. During this time, they require complete darkness. Blue-spectrum lamps are needed to stimulate growth, and red-spectrum light sources are needed during flowering.
Onions can grow well In natural light, but sometimes it requires additional lighting. Grow lights are most often used. The onion leaves become firm, and the fruits become large and firm.
For strawberries grown in a greenhouse, 1-meter-long fluorescent lamps are suitable. Their power should be between 40 and 50 watts. A single lamp can provide light for 3-6 square meters of greenhouse space. Strawberries require 130 to 150 lux, which they will receive regularly for 12-14 hours. Only warm-spectrum lamps should be used.
Strawberries require constant daylight (14 to 18 hours per day). In the wild, they begin to bloom in May. When grown in a greenhouse, daylight hours are increased using neon, fluorescent, or mercury-vapor light sources. This stimulates photosynthesis, resulting in a deep green foliage. Under artificial lighting, strawberries ripen much earlier than in the wild.
In the first days of growth, tomato seedlings are illuminated for 20 hours, gradually reducing the lighting intensity to 16-12 hours per day.
Calculating the amount of lighting for greenhouses
To calculate the required number of lux for one greenhouse, use the formula F=ExS/Ki. In this case:
- F — luminous flux;
- S — area of illuminated room;
- Ki is the luminous flux utilization factor. For light sources with a built-in reflector, it is 0.8. For lamps with an external reflector, it is 0.4.
For example, we have a greenhouse with an area of 14 m2. 12,000 lux can be taken as the illumination level. We perform the following calculation:
14,000x12:0.4. We get 420,000 lumens.
Each plant is illuminated with a 20-30W lamp. The lamp should be positioned at a height of 50-300 mm. For group plantings, 50W lamps are needed. The distance from the light source to the top leaves of the plant is 400-600 mm. For larger greenhouses, the lamp power can be increased to 100W. Larger winter greenhouses are often illuminated with 250W lamps, positioned at a height of 1-2 m.
Reviews
Valery (Arkhangelsk):
"I installed lighting in my winter greenhouse using regular incandescent bulbs. I regularly monitor the heat to avoid burning the plants. Everything would be fine, but they consume too much electricity. A friend recommended switching to fluorescent bulbs. I think I'll start rebuilding the lighting system this summer to save on electricity."
Arina (Moscow):
"Last summer, we built a large winter greenhouse. We immediately decided to install fluorescent lamps. They're energy-efficient and safe, but we couldn't part with two old mercury-vapor lamps, which we also installed indoors. Berries require constant light during the day, and even more so in winter and fall. They need about 14 hours of uninterrupted light. Our combined lighting proved to be very helpful. The strawberry leaves grow large, and the fruit is fleshy and aromatic. Our strawberries ripen earlier in the greenhouse than in the forest, and our neighbors are constantly amazed by this. Mercury-vapor lamps must be handled with care, as with any glass electrical appliance."
Artem (Penza region):
"I have a small greenhouse where I grow herbs, cucumbers, and tomatoes year-round. I installed LED lights and I don't regret it at all. Many criticize them, saying they burn out quickly. All I had to do was completely replace the wiring to prevent short circuits and other problems. Of course, it wasn't without some financial investment, but a year later, it's been worth it. I'm pleased with the energy savings and the smooth operation of the LED lights. They're compact and lightweight, and can be placed at any height. Each light has a dimmer, allowing me to increase or decrease the light. I use blue lights for seedlings and red and orange lights for mature plants. The fruits are large and ripe."
Proper lighting for a winter greenhouse is the key to successfully growing vegetables, herbs, and berries year-round. Preliminary calculations of the required lumens will help you plan the installation of lighting equipment and ensure its proper use.