For plant growth and development, light waves in specific parts of the spectrum are required. In our color perception, this is light in the red and blue range.
The blue part of the spectrum has wavelengths of 420-460 nm and the red part has wavelengths of 630-670 nm. Plants need the rest of the plants grow light spectrum, but in much lesser quantities.
When planting seedlings and maintaining the greenhouse, the plants "light up" and they extend the daylight hours with the help of additional lighting. You can do this with ordinary lamps, as their spectrum also contains the desired range of light radiation.
Plants grow lights are different in that the grow light spectrum consists primarily of waves of the desired length. So in theory they will be more economical than regular backlights.
In fact, less energy is consumed by the plant's "unnecessary" spectrum, also known as agricultural lights. Not only do they sell individual bulbs, but entire fixtures as well. They are also known as grow lights, also known as plant fill lights.
Special lamps for plant lighting can be of different types. Changing the glow spectrum here is simply not possible without a normal incandescent lamp.
High Pressure Sodium (HpS), Metal Halide (MGL), Mercury Discharge Lamp (DRL), Fluorescent Grow Lights (with different connectors, including standard E27), LEDs (ribbon, lamps with different sockets).
1. High pressure sodium lamp
This 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 seedlings, with basic sodium grow lights that allow light to travel in all directions.
This is acceptable for a greenhouse, but inconvenient for a house because it makes it invisible to the eyes. Conventional sodium farm lamps can be installed in lighting fixtures with reflectors.
They produce roughly the same effect as a mirror coating, and for small projects, boxes with reflective walls can be made. This reduces the cost of grow lights, but in small volume situations, air temperature must be monitored - this type of light can get very hot.
2. Metal halide lamps (MHD) for plants
This is one of the subspecies of gas discharge lamps characterized by the presence of halogen vapors in the bulb. The rest of the structure is very similar to other gas discharge lamps.
If we look at the spectrum emitted by this type of grow light, we see clear pulse trains in the green and orange regions. Less blue, but enough.
With an extended red spectrum, MGL lamps are suitable not only for the start of the growing season, but also for crop formation and maturity. So you can choose a spectrum for any type of plant, but the price of special lights is not satisfactory.
3. Mercury Discharge Lamp (DRL)
The difference between such gas discharge lamps is that they can be used without additional equipment. Simply screw the grow light into a standard socket connected to a 220 V network.
The second point is that the bulb is made with a mirror coating, which allows you to create a directional flow of light without wasting energy on "lighting the ceiling". Gas discharge mercury grow lamps are called DRLFs. Radiation is more intense in the red and blue parts of the spectrum.
4. Fluorescent plant light
This is also a type of gas discharge lamp, and can be grown using conventional fluorescent grow lights, but it is tall and thin and has underdeveloped roots. So, after all, it is better to use special lamps. They are many times more expensive than conventional ones, but this is due to the more complex production process.
5. LED grow lights for herbs
LED grow lights red and blue elements have been added to them to some extent. The only problem is that they are also made for vegetation and flowering. For seedlings, they are ineffective, with weak roots and long internodes. Therefore, for seedling growth, it is best to make your own lights, or add blue.
In general, LED grow lights are an economically correct solution. There are also opponents of LED grow light technology, but they have no clear arguments.