Plant lamps are used for indoor gardening, plant reproduction 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 light efficiency. The lamps or lamps are moved as close as possible so that they have the same illumination and all light from the lamps falls on the plants rather than the surrounding area.
Examples include incandescent, fluorescent, metal halide (HID) lamps and light emitting diodes (leds). Today, the most widely used professional lamps are HID and fluorescent lamps. Indoor flower and vegetable growers commonly use high pressure sodium (HPS/SON) and metal halide (MH) HID lamps, but fluorescent and LED bulbs substitute metal halides for efficiency and economy.
Metal halide lamps are often used during the vegetative phase of plant growth because they emit more blue and ultraviolet radiation. With the introduction of ceramic metal halide lighting and full-spectrum metal halide lighting they are increasingly used as exclusive light sources for vegetative propagation and growth. The blue spectrum may induce a greater nutritional response in plants.
High pressure sodium lamps are also used as a single light source throughout the nutritional and reproductive stages. Similarly, they can be used as corrections for full-spectrum lighting during the reproductive phase. The red spectrum may trigger a greater flowering response in plants. Plants grow slightly faster when high pressure sodium is used as the nutrient phase.
In recent years, LED indoor growth lights have been able to generate light at specific wavelengths. NASA has been testing to increase the efficiency of space food on the space station. The results show that plants are affected by light in the red, green and blue parts of the visible spectrum.
2.The specific needs of a plant determine which kind of lighting is best for growth, and artificial light must mimic the natural light for which the plant is best suited. If a plant doesn't get enough light, it won't grow, regardless of other conditions. For example: vegetables grow best in full sunlight and thrive indoors, where they need the same high level of light, while leaf plants (such as tendrils) grow in shade and can grow normally at lower levels of light.
The way plant lamps are used depends on the stage of plant growth. In general, 16 hours of exposure and 8 hours of rest are recommended during the seedling/growth phase; 18 hours of exposure and 6 hours of rest during the nutritional phase; 12 hours of exposure and 12 hours of rest during anthesis.
In addition, many plants also need darkness and photoperiod, an effect known as the photoperiod, to trigger flowering. Therefore, the light can be turned on or off at a set time switch. The optimal photoperiodic ratio depends on the type and type of plant, as some prefer long and short nights, while others prefer opposite or medium days.
Photoperiod is very important when discussing plant development.
Plants that respond to photoperiod flowers may have facultative or specific responses. The part-time response means that a plant will eventually run out, regardless of the photoperiod, growing faster at a given photoperiod. Specialized response means that plants will only flower if they are planted under certain light conditions.