The distance of lighting to plant tops varies depending on the choice of lighting you decide to use, quantity of heat generated by the lights and therefore the amount of plants you grow beneath them. In general, with HID (High Intensity Discharge) lighting—including MH (Metal Halide) and HPS (High-Pressure Sodium)—individual 1000-watt lights ought to be unbroken 24 – 30 inches from the canopy; 600-watt lights ought to be 18 – 24 inches away; and 400-watt lights is as shut as 12 – 18 inches from plant crack. Keeping your space cooler and supplementing with CO2 gas will enable you to put lights a little nearer.
Raise lights if heat at your leaf surface is just too high. Use a light meter if you’ve got one, or if not, merely place your hand at the amount of the plants below the light. If it looks too hot, raise the light or lower the plants. Bleaching buds, burning leaves or plants stressing out area unit sometimes a certain sign that the light is just too shut. Fluorescent and LED (Light Emitting Diode) lights generate abundant less heat while penetrating much less into the cover, so that they ought to be unbroken considerably nearer to plant crack.
In industrial or business growing applications, lights is higher as a result of you’re exploitation a lot of lighting and spreading it around. That’s why business lighting hoods area unit smaller, and therefore the hoods you ought to purchase for growing under just one light got to be larger and direct light downwards into a tighter light footprint.
Also, forever make sure to either lower the lights and lift them because the plants grow taller, or as another, you’ll be able to raise the plants towards the light ahead of time so lower them as they grow. One huge mistake I see over and over is that growers install the light too high so let the plant become old towards it. This ends up in long and lanky plants that struggle to carry themselves up and want staking or trellising so as to stay from falling over. It’s a waste of area and time.