Grow lamps produce a lot of light, and a lot of heat. While indoor gardeners are always hungry for more efficient ways of producing the all-important photons to drive photosynthesis, heat is like the uninvited and troublesome guest that snuck into the backseat. Heat rears its ugly head in three primary ways in your indoor garden:
This is heat caused by physical contact between one material and another. Think of a warm nutrient solution being sucked up into your plant and heating the cells it comes into contact with, or a warm pot under the glare of your grow lights heating up the growing media inside it. Conduction heat spreads physically from one material to another, like a chain.
This is heat carried in the air. A hot material heats up the air around it and this air comes into contact with other materials. A “thermal transfer” takes place with the air acting as a sort of transporter. Think of the air surrounding your grow lamp and reflector, heating up, and then being moved around the room with your oscillating fans, and then coming into contact with the epidermis of your plants or pots or growing media.
This is heat that can travel through a vacuum (g. solar rays traveling through space) as waves—similar to light, but at lower frequencies (760 nm to 1mm). We call this type of heat infrared. Infrared radiation does one or more of three things when it hits a material (such as a wall, leaf, reflector, soil, water, anything!) — it can pass through it (transmission), bounce off it (reflection) or heat it up (absorption).Materials which absorb infrared then re-emit it, typically at a lower wavelength. So if your reflector becomes hot during operation it then acts as an IR-sync and re-emits mid to far range infrared. Where? Right down at your plants!