500 Watt LED Grow Lights - A grow light is used to stimulate plant growth. These are artificial light sources that emit an electromagnetic spectrum necessary for photosynthesis. Grow lights are usually electrically powered lights. They are useful in two types of situations: where supplemental light is required, and where there is no natural light.
Grow lights may be used during the winter months when the available daylight hours are not enough for the plant to grow. They may be used in a growing room that has no access to daylight.
Grow lights may be designed to provide a light spectrum comparable to that of the sun, or they may be designed to emit a spectrum specially tailored to the needs of the particular plants under cultivation. Lamps come with varying colour temperatures, spectral outputs, and varying intensity (known as lumen output). Specific ranges of spectrum, luminosity and colour temperature can be tailored to the type of plant being cultivated, the photo period required, and whether or not the plant is in the germination/vegetative phase or the flowering/fruiting phase of growth.
Grow lights can be applied in an industrial growing operation or in households. Grow lights are used for a variety of applications, such as indoor gardening, plant propagation and food production. They are used for indoor hydroponics and aquatic plants.
Indoor growers employ many techniques to maximize the efficiency of their light source. The intensity of light radiating from a bulb as it reaches a surface is inversely proportional to the square of the surface's distance from the source. This means that if the plant is twice as far away from the bulb, it receives only a quarter the light.
Growers ensure that all light coming from the lights falls on the plants rather than on the surrounding area by arranging the plants as close together as possible. With incandescent lights, the light maybe as far as 60 cm distant from the plants. With other types of lighting, such as fluorescent lights, the light can be up to 10 cm distant from the plants. One of the most common techniques to maximize light efficiency is the use of reflectors. A common practise is to cover the grow-room walls with reflective material. Painting the walls white is an alternative way to maximize efficiency.
There are many different types of lights that will work as grow lights. Incandescents, fluorescent lights, high-intensity discharge lights (HID), and LEDs. Currently, professional flower and vegetable growers tend to choose HIDs and fluorescents. The most common are high pressure sodium (HPS/SON) and metal halide (MH) HID lights. However, fluorescents are more efficient and economic, and they are gradually replacing metal halides.
The vegetative phase of growth requires a bluish light, which is what metal halide HID lights are good for. HPS lights are used for next phase of growth, which is the reproductive stage. This stage requires red spectrum light to trigger the flowering response. HPS lights can be used for the vegetative phase, and plants grow slightly more quickly, but they will have longer internodes, and may be longer overall.
MH bulbs can have a reddish spectrum added. Likewise, HPS bulbs can have the bluish spectrum added. These fuller spectrum lights have the benefit of providing flexibility during both phases of plant growth.
Today's high quality LEDs emit only the wavelengths of light corresponding to the absorption peaks of a plant's typical photochemical processes. Modern technical advancements allow LEDs to be produced relatively inexpensively. These grow lights are a longer-lasting alternative to the other types of grow lights. Increasingly, indoor growers are choosing LEDs because these lights use less electricity, produce very little heat and do not require ballasts. LEDs can safely be placed closer to the plant canopy than other lights. When subjected to less heat, plants transpire less, which means they can go longer between waterings.
LED designs vary widely. LED grow lights may use one or more LED colours overlapping multiple absorption peaks for chlorophyll and carotenoids. The ratio of blue, to red, to orange light varies according to different claims about how best to maximize plant growth. Opinions vary, but blue LEDs may be recommended for vegetative growth, while a greater proportion of deep-red LEDs may be recommended for growing fruits or flowers.
LED grow light designs used to require hundreds of fractional-watt LEDs . Even then, they often lacked the brightness and efficiency needed to effectively replace HID lights in indoor growing operations. The newest and most advanced LED grow lights have achieved growing results comparable to HID lights. The new generation of LEDs are more effective, and are consuming more power. Today's LEDs are 3 watts or 5 watts, higher than the typical 1-watt older designs. Some LED grow lights exceeding 600 watts are available.
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