In this article we provide an overview of three main grow light technologies: indoor LED grow lights, Fluorescent Lights and HID lights. We do not cover incandescent light as these are no longer regularly used for grow lights indoor gardening, only for garden lighting. The best grow lights are able to mimic the precise wavelengths of light that can be used by plants in their photosynthesis and thereby provide the energy for plant growth, flowering, seedling and so on. So lets get started on the three grow light types.
LED grow lights are a popular and cost effective choice for the indoor gardener. Studies have shown them to use around 60% of the energy required by HID lighting systems. Their lifespan is also far longer, with the diodes typically lasting between 50,000 and 100,000. The vast majority of the light that is emitted is in wavelengths that can be absorbed by plants and used for photosynthesis with little wasted either as heat or non usable visible light.
Incandescent lights are now rarely used for grow lighting purposes. They have been replaced by more cost effective and longer lasting fluorescent bulbs. Higher output fluorescent light bulbs are also available. These are more expensive than the standard bulbs but produce a more concentrated light and are available in a range of colors corresponding to the wavelengths of light that are most used by plants.
Higher Intensity Discharge Lights, and in particular High Pressure Sodium (HPS) and Metal Halide (MH) grow lights are a popular choice among grow light gardeners. Although the set up and running costs are high, they are highly effective at stimulating photosynthesis in plants. HPS and MH plants are often used in combination to ensure that wavelengths of blue and orange lights (the colors that corresponding to maximum chlorophyll absorption points) are emitted.