Reflective Hoods

Marijuana Horticulture

by Jorge Cervantes

Some reflective hoods reflect light more evenly than others. A reflector that distributes the light evenly – with no hot spots – can be placed closer to plants without burning them. These hoods are most efficient, because the lamp is closer and the light more intense. The farther the lamp is from the garden, the less light plants receive.

For example, a 1000-watt reflector with a hot spot must be placed 36 inches above the garden. A 600 watt lamp with a reflector that distributes light evenly can be placed only 18 inches above the garden. When placed closer, the 600-watt lamp shines as much light on the garden as the 1000-watt bulb!

The proper reflective hood over the lamp and reflective walls can double the growing area. growers who use the most efficient reflective hoods harvest up to twice as much as those who don’t.

Seedlings, cuttings, and plants in the vegetative growth stage need less light than flowering plants, because their growth requirements are different. For the first few weeks of life, seedlings and clones can easily survive beneath fluorescent lights. Vegetative growth requires a little more light, easily supplied by a metal halide or compact fluorescent lamps.

Reflective hoods are made from steel sheet metal, aluminum, even stainless steel. The steel is either cold-rolled or pre-galvanized before a reflective coating is applied. Pre-galvanized steel is more rust resistant than cold-rolled steel. This metal can be polished, textured or painted, with white being the most common paint color. Premium hood manufacturers apply white paint in a powder coating process.

The pebble a hammer-tone surfaces offer good light diffusion and more surface area to reflect light. hot spots are commonplace among highly polished, mirror-like surfaces. Mirror-polished hoods also scratch easily and create uneven lighting.