Artificial sunlight is generated by light bulbs. Plant life has evolved to make energy by taking in sunlight, water, and carbon dioxide through the process of photosynthesis. Growing plants with an artificial light source requires duplicating to the greatest extent possible the natural light conditions created by the sun and required by the plant. Ideally, artificial light should not emit excessive amounts of heat and should provide light in both the red and blue spectrum
Incandescent bulbs are a poor source of artificial plant light because they produce a lot of heat and light in the blue spectrum. The high heat output requires the placement of incandescent bulbs at a substantial distance from the plant, reducing the amount and intensity of the light received. An incandescent light bulb lasts about 1,000 hours and is inefficient at utilizing and converting electricity.
Florescent tubes are optimal sources of artificial plant light because they operate at cooler temperatures than incandescent bulbs and produce light in both the red and blue spectrum. The reduced heat output of fluorescent tubes allows the light source to by closer to the plant, providing more intense light for the plant. Fluorescent tubes average 10,000 hours of use and come in many shapes and sizes including square, U-shaped, or straight.
Spotlights can be incandescent or florescent and provide supplemental artificial light either in addition to other artificial sources or in addition to natural light. Spotlights can fill a gap in light intensity or light duration and are generally less effective and efficient than standard florescent tubes. Specialize self-reflecting spotlights are coated to emit greater amounts of blue light in a concentrated area and greatly aid standard incandescent bulbs.