Intensity

Marijuana Horticulture

by Jorge Cervantes

High intensity discharge lamps are bright – very bright. Growers who properly manage this intense brightness harvest more weed per watt. Intensity is the magnitude of light energy per unit of area. It is greatest near the bulb and diminishes rapidly as it moves away from the source.

For example, plants that are two feet from a lamp receive one-fourth of the amount of light received by plants on foot away! An HID that emits 100,000 lumens produces a paltry 25,000 lumens two feet away. A 1000-watt HID that emits 100,000 initial lumens yields 11,111 lumens three feet away. Couple this meager sum with a poorly designed reflective hood, and beautiful buds suffer big time! The closer marijuana is to a light source, the more PAR watts it receives and the better it grows, as long as it is not so close that heat from the lamp burns foliage.