Plant growth lamps are artificial, usually electrical, light sources designed to stimulate plant growth by emitting an electromagnetic spectrum suitable for photosynthesis. Plant lamps are used in applications where there is no natural glow or where supplementary light is required. For example, in winter, when the possible daylight hours may not be sufficient to achieve the desired plant growth, lamps are used to extend the time that plants receive light. If plants do not get enough light, they will grow in vain.
The growing light either attempts to provide a spectrum similar to that of the sun, or to provide a spectrum more suited to the needs of the cultivated plant. Simulate outdoor conditions from increasing the lamp's different color, temperature, and spectral output, as well as changing the lamp's lumen output (intensity). Depending on the type of plant being cultivated, the stage of cultivation (e.g. germination/vegetative stage or flowering/fruiting stage) and the photoperiod required by the plant, specific ranges of the spectrum, luminescence efficiency and color temperature are all desirable for specific plants and time periods.
Plant lights are used for indoor gardening, plant propagation and food production, including indoor hydroponics and aquatic plants. Although most plant lamps are used in industry, they can also be used in the home.
According to the inverse square law, reach the surface of the point source (in this case is the light bulb) radiation intensity of light source and surface distance is inversely proportional to the square of the distance of (if a twice as distant place, it receives only a quarter of the light) this is the serious obstacle indoor growers, many techniques are used to use light as efficiently as possible. Therefore, reflectors are often used for lighting to maximize the light efficiency. Luminaires or lamps are moved as close together as possible so that they have the same lighting and all light from the lamps falls on the plants rather than the surrounding area.
Examples include incandescent lamps, fluorescent lamps, metal halide lamps (HID) and light-emitting diodes (LED). Today, the most widely used lamps in professional use are HID and fluorescent. Indoor flower and vegetable growers often use high pressure sodium (HPS/SON) and metal halide (MH) HID lamps, but fluorescent lamps and LEDs have replaced metal halides due to their efficiency and economy.
1.High intensity discharge (HID) lamps
While fluorescent lights were a common type of indoor growth light in the past, HID lights are now the most popular. High intensity discharge lamps have high lumen/watt efficiency. There are several different types of HID lamps, including mercury vapor, metal halides, high pressure sodium and conversion bulbs. Metal halides and HPS lamps produce some chromatograms that are somewhat similar to the sun and can be used to grow plants. Mercury vapour lamps were the first HIDs and were widely used for street lighting, but when it comes to indoor gardening, they produce a relatively poor spectrum for plant growth, so they are mostly replaced by other types of HIDs for growth plants.
2.LED (Light Emitting Diode)
LEDs consist of light-emitting diodes (LEDs), usually in a housing with a radiator or built-in fan. LED lights usually do not require a separate ballast and can be plugged directly into a standard electrical outlet for use.
LED growth lights vary according to their use. Green, red, far-red, and blue spectra are known to have an effect on root formation, plant growth, and flowering from photomorphogenesis studies, but not enough scientific studies or field tests of the specific color ratios recommended by experiments using LED growth lamps have been conducted. It has been shown that many plants will grow normally if given red and blue light. However, many studies have shown that red and blue lights provide only the most cost-effective growth methods, and plants are still better off growing in light-supplemented green.