Grow light

Grow lights are electric lamps designed to promote plant growth by emitting an electromagnetic spectrum appropriate for photosynthesis. It does this by mimicking the light spectrum from the sun, allowing indoor growth with outdoor conditions.

Different light spectrums are used for the different stages of plant growth. The initial vegetative stage requires blue spectrum of light, whereas the later 'flowering' stage should be done with red/orange spectrums. The lights can be bought by spectrum colour specifically, or some companies such as Sylvania Grolux produce a full spectrum bulb which caters for all stages of growth.

The light is usually used in conjunction with a reflector, to control and intensify the light emissions, and will include an electrical ballast to control the flow of current flowing to the light. This is required because of the high intensity of the light that is necessary to produce something akin to sunlight. But because of this intensity hydroponics can lead to double or more growth rate than regular growing.

In 2006 an invention entitled 'Plug and Grow' was trademarked by Andrew Varley and Andrew Greenwell of TradeHydro.com which was a self-ballasting light, making the ballast redundant and allowing the grower to simply plug it in to a standard socket and grow straight away, without worrying about the high electricity usage.

Lamp types used as grow lights include high-intensity discharge lamps and fluorescent lamps. Grow lights are most used for indoor gardening, including indoor hydroponics.