Light Meters

Marijuana Horticulture

by Jorge Cervantes

Most commercial light meters measure light in foot-candles or lux. Both scales measure light which the human eye reacts to “see”. They do not measure photosynthetic response to light in PAR watts.

Light measurements in this book are made in foot-candles and lux. This information is still valuable, because it record the amount of light spread over a specific surface. The information is often coupled with the PAR rating of different bulbs. Regardless of the lamp, the amount of light emitted is constant. It only makes sense to use a proper reflective hood with a high PAR-rated bulb to grow the best garden.

After all the talk about PAR watts, industry officials are unable to agree on a common scale of measurement. For this reason, we have decided to rely on Kelvin color temperature to measure lamp spectrum.