By Adam Jacques

There are many options available when it comes to lighting hoods, and a grower may have a tough time figuring out which is best for their garden. To best make this choice there are several questions that should first be answered. The first consideration is room temperature. Lighting hoods are available as air or liquid cooled because most types of grow lights produce a considerable amount of heat, and unless the room is designed to remove the heat from the space, the hood should be part of a sealed cooling circuit so that heat may be removed. The next thing to consider is room height. Most types of lights are at home 12” to 24” above the plant canopy, while others, such as double-ended type fixtures broadcast to a larger footprint and should be located at 48” – 60” above the canopy. Once a horticulturist has designed their room, other things to consider with regards to hoods are the lighting footprint and room layout. Round or Parabolic hoods are best used over a round cluster of plants. Rectangular hoods are designed typically to broadcast over a 3’ x 3’ or 4’ x 4’ square and compliment a garden which is in rows or a ‘sea of green’ layout. Bare hanging bulbs also work well for a room setup in rows but should be placed to maximize the 360 degrees of light output. In addition it should be noted that glass, while being ideal to seal the business end of a cooled hood, does block some of the available photons from reaching the plant canopy. Lastly, most bulbs broadcast out 360 degrees but a hood generally covers 270 degrees of the actual bulb; while there are numerous reflector types which are designed to defuse the light photons back to the plant(s), a lot do get lost in the process.