Plant lighting
Without exaggeration, light can be called a source of life for plants and the main condition for their successful growth. Without light, the photosynthesis reaction that provides the plant with nutrition is impossible, and it can slowly die from hunger. With a lack of light, plants weaken and cannot resist pests and diseases. In indoor conditions, as well as in greenhouses and greenhouses, natural light is not enough not only in winter but also in summer, and therefore the additional illumination of plants with electric lighting devices remains one of the main factors for the successful growth and health of decorative, aquarium and even vegetable green pets growing in our winter gardens and window sills.
Content
- Characteristics of lighting electrical appliances
- Watts, Suites, Lumens
- What is affected by the spectrum and color of light
- Types of lamps for lighting plants
Characteristics of lighting electrical appliances
When creating artificial lighting for indoor plants, it should be clearly understood which of the two possible functions it will perform:
- afterglow
- full coverage
If your green pets are located near windows, on a glazed terrace or loggia, then they most likely need periodic lighting, which will compensate for the lack of natural light and have a beneficial effect on their growth, development and flowering. In this case, the choice of lamps does not matter much, and the use of a dual-mode timer-relay will automatically provide the plants with the necessary amount of light in the mornings and evenings.
Illumination of indoor plants on the windowsill
Quite often, plants are grown under artificial lighting, that is, in rooms without windows or in corners of the room remote from windows. In a situation where your plants are not at all familiar with natural daylight, they need to select lamps with a special spectrum that meets the needs of decorative indoor or aquarium green spaces.
Watts, Suites, Lumens
To choose the right lamps for plant lighting, each grower needs to remember from the school physics course what lamp power, light flux, illumination are, what they affect and in what units they are measured.
The power of an electric lamp is measured in watts..
Luminous flux is the main characteristic of a light source, measured in lumens and the higher the indicator, the more light the lamp emits.
Illumination is a characteristic of a surface illuminated by a light source, measured in lux. How much time it will take to illuminate a particular surface area depends on the indicator of illumination.
Thus, the luminous flux of 1 Lm, illuminating an area of 1 sq. M, provides it with an illumination of 1 Lx. When designing an artificial lighting system for your home greenhouse, there are two important rules to consider:
- The amount of illumination is inversely proportional to the square of the distance from the light source to the surface. That is, raising the lamp just 50 cm above its previous level, for example, half a meter above the plants, we increase the area of lighting, but reduce the level of illumination by 4 times.
- The level of illumination depends on the angle at which the light is directed to the surface. By analogy with the sun at its zenith, a searchlight type light source will provide maximum illumination if it is located perpendicular to the illuminated area.
What is affected by the spectrum and color of light
Natural or artificial light is a combination of electromagnetic waves of various lengths, called the spectrum of light. The light spectrum consists of constituent spectral parts, each of which corresponds to its own part of the spectrum of a certain color, visible or invisible. The visible part of the spectrum is perceived by vision as white light, and the invisible ones are ultraviolet and infrared radiation. All parts of the light spectrum play an important role in the development of plants..
During photosynthesis, chlorophyll and other plant pigments, with the participation of light, absorb carbon dioxide and produce oxygen, converting the energy of light into energy necessary for life. Moreover, the pigments that “work” in the reaction use light from the red and blue parts of the spectrum. The development of the root system, flowering and ripening of the fruits are “controlled” by pigments, the peak of sensitivity of which is located in the red part of the spectrum. Correctly organizing artificial lighting of plants in one or another part of the spectrum and changing the duration of the light and dark periods, you can accelerate or slow down the development of the plant, shorten the growing season or control other processes.
The spectrum of peaks of sensitivity of plant pigments in different life processes
The most important spectral and color characteristics of lighting devices are indicated on their marking by the following indicators:
- the color temperature of the CCT lamp indicates the color of the radiation, measured in degrees on the Kelvin scale and corresponds to the temperature at which the color of the hot metal is closest to the color of the light of the lighting device;
- CRI lamp color rendering coefficient characterizes the correspondence of the color of the illuminated object to its true color, measured from 0 to 100.
For example, the marking on the lamp “/ 735” means that it is a device with the characteristics CRI = 70-75% and CCT = 3500 ° K, and the marking “/ 960” characterizes a lamp with CRI = 90% and CCT = 6000 ° K, color whose radiation is close to daylight.
It is important to remember! In the light of a lamp designed to illuminate plants, the colors of both the red and blue parts of the spectrum must be present.
Types of lamps for lighting plants
For illumination or full artificial lighting of decorative indoor plants, the following types of lighting devices are used:
- incandescent lamps;
- gas discharge lamps;
- LED lamp.
Applicable incandescent bulbs
The oldest well-known type of lamp, in which a red-hot tungsten spiral placed in a glass flask serves as a light source. They are screwed into the cartridge and do not require special equipment to connect. In addition to the usual “Ilyich’s bulbs”, some other, improved types of lighting devices belong to the group of incandescent lamps:
Characterization of halogen lamps
A mixture of xenon and krypton gases is pumped inside the bulb of these lamps, providing a brighter glow and durability of the incandescent spiral. Not to be confused with gas discharge metal halide lamps..
Halogen incandescent lamp with integrated reflector
Why are neodymium lamps good??
Neodymium alloy is added to the glass of lamps of this type, which ensures the absorption of radiation from the yellow-green part of the spectrum. As a result, in the light of a neodymium lamp, the illuminated surface seems brighter, although the amount of emitted light does not increase.
A common drawback of incandescent lamps is the lack of blue radiation in their spectrum and a too low light output of 17-25 Lm / W, and therefore they are not very suitable for lighting plants. In addition, incandescent lamps become too hot and, when located at a height below 1 m, they can cause burns to plants, and at a height above 1 m they are not able to provide effective lighting.
Gas discharge incandescent devices
In contrast to incandescent lamps, light radiation in gas discharge lamps is the result of an electric discharge between two electrodes in a gas mixture. Depending on the composition of the gas mixture, they can emit light from any part of the spectrum. Distinguish gas discharge lamps
- low pressure – fluorescent lamps, widely used for lighting residential and other premises;
- high pressure – the scope of this type of lamp is much wider, from street lighting to lighting of special objects.
To connect all types of discharge lamps, with the exception of the latest models of energy-saving fluorescent devices, a special ballast is required – ballast, despite the fact that the base of some of them looks similar to the base of a conventional incandescent lamp.
Low pressure fluorescent lamps are a glass tube, on both sides of which are located a pair of electrodes connected by a tungsten spiral. Inside the tube there is a mixture of inert gas and mercury vapor, and the inner surface of the glass tube-tube is coated with a special composition – a phosphor. As a result of an electric discharge, mercury vapor generates ultraviolet radiation that is invisible to the eye and is transformed by the phosphor into visible white light. There are three types of fluorescent lamps.
General Purpose Fluorescent Lamps
Lamps of this type are widely used for lighting rooms, they are distinguished by high light output of 50-70 Lm / W, low thermal radiation and long service life. They can be used for periodic illumination of indoor plants, but due to the limited spectrum, the use of such lamps for regular lighting of a home greenhouse is not always optimal.
Lighting aquarium plants with fluorescent lamps
Special purpose fluorescent devices
This type of fluorescent lamp differs from the previous one in the composition of the phosphor deposited on the inner surface of the glass tube. As a result of the improvement, the spectrum of the light emitted by the lamp is close to the spectrum that plants need. With the same power, the lamp emits a greater amount of light precisely of the “useful” part of the spectrum, and therefore is suitable for any need: whether full lighting is required for indoor plants, periodic illumination or decorative illumination.
Compact fluorescent tubes
The main difference between this type of fluorescent lamps from the previous two is the ballast integrated in the base, thanks to which they are easily integrated into any circuit apartment lighting or at home without additional expensive equipment, that is, they simply screw into any cartridge of the appropriate size. Being a worthy replacement for a conventional incandescent lamp as a lighting device, an insufficiently wide range of compact energy-saving lamps is not able to provide effective illumination of indoor plants. Moreover, their significant drawback is the size of the lamp: a compact fluorescent lamp with a power of 20 W or more (corresponding to an incandescent lamp power of 100 W) can be used to illuminate only a small group or a separate plant, placed at a height of 30-40 cm.
Compact fluorescent lamp with integrated ballast
More effective in the role of lighting devices for plants are compact fluorescent lamps with increased power of 36-55 watts. They differ from ordinary fluorescent lamps in higher light output and longer service life, and their excellent light transmission CRI = 90% and a wide range containing red and blue colors can provide plants with comfortable lighting. It is recommended to use such lamps with a reflector in those cases when the total power of lighting devices not more than 200-300 W is sufficient for lighting a home flower garden. So far, their only drawback is the too high price and the need for electronic ballast to connect.
High-pressure discharge lamps are one of the brightest light sources; they are distinguished by high light output and convenient compact dimensions. One lamp is able to effectively illuminate plants over a fairly large area. Lamps of this type are connected to the mains via a special ballast, and it is recommended to use them for lighting plants in cases where a lot of light is required, which lighting devices with a total power of 200-300 W do not provide. The following types of high-pressure discharge lamps are used to illuminate home greenhouses and greenhouses:
- mercury;
- sodium;
- metal halides, sometimes called metal halides.
High pressure mercury lamps
The oldest generation of discharge lamps. If the inner surface of the flask is not coated, they have a very low color rendering coefficient and an unpleasant bluish color of radiation. The mercury paws of the latest generation are internally coated with a special compound that improves their spectral characteristics, and some manufacturers have even adapted lamps of this type to illuminate plants. But such a disadvantage as low light output has not yet been eliminated.
Sodium Discharge Lamps
Effective bright lamps with a high light output, characterized by a very high resource of 12-20 thousand hours. The spectrum of sodium lamps is represented mainly by the red zone that regulates the processes of root formation and flowering of plants. One gas discharge sodium lamp with a power of 250 watts, equipped with a built-in reflector, is able to effectively illuminate an impressive area of a winter garden or a large collection of plants. To balance the emission spectrum, it is recommended to alternate sodium lamps with mercury or metal halide lamps..
To connect a metal halide lamp, a special cartridge is required, despite the fact that its base is similar to the base of an incandescent lamp
Perfect metal halide lamps
The most advanced type of discharge lamp as a lighting fixture for plants. They are distinguished by high power, a large resource and an optimally balanced, comfortable spectrum for plants. To connect a metal halide lamp, a special cartridge is required, despite the fact that outwardly its base is practically no different from the base of an incandescent lamp. The disadvantage is that the cost is too high compared to other types of lamps.
LED lighting devices
Unlike all devices used for lighting or illumination of plants, an LED lighting device is not a lamp, but a solid-state semiconductor device in which there is no fragile glass bulb filled with unsafe gas, filament and unreliable movable elements. Radiation in the LED is generated when an electric current passes through a special artificial crystal. The main energy is spent on creating a luminous flux, the process takes place without heat – a very important advantage that allows you to create the perfect lighting for aquarium plants suffering from overheating.
Progressive LED lightening for plants of any type, it is considered to be the technology of the future. LEDs are distinguished by an unrivaled resource of up to 100 thousand hours of continuous operation, consume 75% less electricity compared to traditional lighting devices and are able to provide a radiation spectrum that is comfortable for the development of plants. It is very important that the absence of ultraviolet and infrared parts of the spectrum guarantees the complete safety of LED devices for people and plants.
The color of LED lighting depends on the composition of the crystal through which the electric current flows, and the radiation intensity can be adjusted by changing the current strength. If one lighting device consists of several crystals, each of which emits light of a certain part of the spectrum, then the current strength of each of them can be controlled. The only drawback of LED light sources is that they are quite expensive compared to traditional lamps.
LED plant lighting
Thus, the choice of lighting devices allows each gardener, regardless of budget, to create normal lighting for their plants.
The cheapest option is incandescent or compact fluorescent lamps with integrated ballast that fit conventional lampholders.
Compact fluorescent lamps are excellent for illuminating a small number of low plants closely spaced to each other. Tall free-standing plants are best illuminated with floodlight type sodium discharge lamps of low power up to 100 W.
Plants of approximately the same height located on shelves or window sills are best illuminated with long or compact fluorescent lamps of high power. The use of a reflector with fluorescent lamps significantly increases the useful flow of light.
To illuminate a large conservatory or an extensive collection of plants, you can use one or more ceiling lights with powerful (from 250 t) gas-discharge sodium or metal halide lamps.
Finally, for each of these cases, modern LED lighting is ideally suited, the high cost of which more than compensates for the comfort, brilliance of green leaves and the colorful blooming buds of your pets.
