Growing house plants, seedlings for the summer cottage is not just for the sake of saving souls. I want the plants to be strong, healthy and to please with leaves and flowers, fruits. In our environment, it is not always possible to do this without extra efforts. The main problem is the short daylight hours. Make it with backlight. And there are special grow lights for this. They are also called grow lights (grow light), agrolamps (agrolamp) (agricultural planting lights). There are enough names, but the essence is the same - they are light sources that allow plants to grow better, bloom and bear fruit.
What is a grow light and how does it differ from the usual lamp?
For the growth and development of plants, light waves in a specific part of the spectrum are needed. In our color perception, this is light in the red and blue range. The wavelength of the blue part of the spectrum is 420-460 nm, and the wavelength of the red part is 630-670 nm. Plants need the rest of the spectrum, but in much smaller quantities.
When growing seedlings, maintaining greenhouses, plants are "illuminated" - they extend the daylight hours with the help of additional lighting. You can do this with ordinary lamps, because their spectrum also contains the required range of light radiation. The difference with plant growth lamps is that the spectrum consists mainly of waves of the required length. Therefore, in theory, they will be more economical than regular backlighting. In practice, the spectrum "unnecessary" for plants consumes less energy. Such light sources are also called agricultural lamps. They sell not only individual bulbs, but also entire lamps. They are also called plant growth lamps, also called plant supplementary lights. But the essence is the same - in such light sources, red and blue light are present in large quantities.
There are two types of grow lamps. Some gas discharge lamps have the entire spectrum, but they differ in that the radiation intensity is higher in the required range. This is reflected in the spectrum diagram of such light sources. The second type of lamps are narrow-segment fluorescent lamps and LEDs. You can distinguish them from conventional light sources by. Since they have mainly red and blue spectrum, they emit violet light.
Types of grow lamps
Special lamps for plant lighting can be of different types. There are no ordinary incandescent lamps - it is simply impossible to change the glow spectrum here. All the others seem to be:
High-pressure sodium lamps (HpS).
Metal halide (MGL).
Mercury gas discharge lamps (DRL).
Fluorescent lamps (with different connectors, including standard E27).
LEDs (strips, lamps with different sockets).
As you can see, the list is long - these lamps are available in stores. None of them is perfect, so for the choice it is desirable to know their characteristics, advantages and disadvantages. We will deal with all the main types, their properties and application features. Let's say right away that we reflect only on technical issues. Effective lighting technology for different growth stages of different types of plants - this is not the subject of our site.
High-pressure sodium lamps
This type of plant light has been around for a long time. It is also used in large greenhouses dedicated to growing vegetables, as well as in large greenhouses dedicated to growing seedlings. With a basic sodium lamp, the light spreads in all directions. This is acceptable for a greenhouse, but it is inconvenient for a house, since it makes it invisible to the eye. There is an improved version of the sodium lamp - DNAZ. Part of the bulb has a mirror coating, which allows you to create a directional stream of light. Regular sodium agricultural lamps can be installed in lighting fixtures with reflectors. They produce approximately the same effect as with a mirror coating. For small projects, boxes with reflective walls can be made. This reduces the cost of backlights, but in small volumes, the air temperature must be monitored - this type of lamp gets very hot.
Metal Halide Lamps for Plants (MHD)
This is one of the subspecies of gas-discharge lamps, which is characterized by the presence of halogen vapor in the bulb. The rest of the structure is very similar to other gas-discharge lamps. Also, for work you need a special lamp - with a control device, and better than electronic lamps. In addition, the protective glass on the plant flask must be strong, since the flask can explode due to high pressure.
If we look at the spectrum emitted by a lamp of this type, we see clear pulses in the green and orange-yellow regions. There is less blue, but it is enough. This color combination is typical for sunlight emitted in early spring. That is, MGF will work at the early stages of plant development - this is an excellent light source for the growth of seedlings. With MGL lamps, plants have a strong root system, they grow actively, do not stretch, and a sufficient number of internodes and buds are laid. The same type of lamp is suitable for lighting aquariums - it promotes the active growth of algae. But at the stage of flowering, ovary formation and fruit ripening, the usual lighting of this type is absolutely ineffective.
MGL lamps have an extended red spectrum, which is suitable not only for the beginning of the growing season, but also for the formation and maturation of crops. Thus, you can choose the spectrum for any type of plant, but the price of special lamps is not satisfactory.
Mercury gas discharge lamps (DRL)
The difference between such gas-discharge lamps is that no additional equipment is required to use them. Just screw them into a standard lamp socket connected to the 220 V network. The second point is that the bulbs are made with a mirror coating, which allows you to form a directional stream of light without wasting energy on "lighting up the ceiling". Gas-discharge mercury grow lamps are called DRLF. The radiation intensity is greater in the red and blue parts of the spectrum.
Fluorescent plant lamps
This is also a type of gas discharge lamp - we know it from household lamps. By the way, you can use regular fluorescent lamps for growing seedlings, but it is tall and thin, and the root system is poorly developed. Therefore, after all, it is better to use special lamps. Yes, they are many times more expensive than conventional ones, but this is due to the more complex production process.
LED (light-emitting diode) plant lamps
LEDs have become cheaper in recent years and are widely used for indoor plant lighting. Production technology allows crystals to grow in a single color. Both wireframe and blue are available. But to illuminate plants, a certain wavelength is needed - LED lamps of this spectrum with 420-460 nm for blue and 630-670 nm for red.
They are available in bulk both in the form of single crystals and in strips of a certain power. If we take a "plant tape", then it contains red and blue LEDs so that a spectrum is obtained, which seems necessary. But usually in LED strips for plants, red light dominates. It favors plant growth, flowering. More blue is needed for root formation. Therefore, "standard" plant tapes are not suitable for seedlings. Unless you buy a separate blue and then add it to the phyto-LED strip.
There are also LED plant growth lights. Red and blue elements are already added to them to some extent. The only problem is that they are also sharpened for vegetation and flowering. For seedlings, they are ineffective: the root system is weak, the internodes are long. Therefore, for seedling growth, it is better to make your own lamps, or add blue again.
In general, LED grow lights are an economically correct solution. There are also opponents of this technology, but they do not have clear arguments - the main argument is that large greenhouses are in no hurry to switch to new grow lights.
