What is a “lumen” and why do I need them?
Growing plants indoors requires a lot of light. Lumens are a scientific term for measuring the visible output of a lamp (or “light bulb” or “bulb”). A standard 60 watt incandescent lamp is rated at an output of 900 lumens. A 400 watt Metal Halide lamp produces 36,000 lumens and a 400 watt High Pressure Sodium lamp produces 50,000 lumens. Generally High Pressure Sodium lamps are more efficient light producers (more lumens per watt), these lamps produce a range of 100-140 lumens per watt, while Metal Halide lamps produce a range of 70-110 lumens per watt.
