Maximum Yield USA 2015 April | Page 102

grow lights on trial from the lamp, which is the main reason they are paired with reflectors. If the light from the HID side is not controlled, it can add to the light received by the plants on the LED side. This can be prevented by placing a physical barrier around both sides of the grow space, but these barriers will also alter air flow, which could benefit one side over the other, depending on the room’s configuration. When LED and HID lights are hung side-by-side in the same space, the LED side can end up acting as a heat sink for the HID side because it runs cooler. Environmental Conditions Environmental conditions also affect the outcome of a trial. Take temperature, for example. HID lamps can harm plants in hot conditions. Plants that are too hot have a difficult time transpiring enough to keep themselves cool, resulting in reduced harvests. Thus, indoor gardens illuminated with HID grow lights always include equipment to ventilate excess heat out of the grow space, and may also include air conditioning to counteract the excess heat generated by HID lamps. Active venting and cooling processes can spell trouble for LEDs as well. Because LED grow lights do not create excess heat, the heat remediation necessary for HID grow lights can cause the LED side to be too cool, which can stunt the plants and suppress yields. Even worse, LED-grown plants can really suffer in cold, wet climates. Without extra heat to keep humidity in check, molds, which are tough to identify under the pinkish glow of many LED grow lights, can thrive. 100 Maximum Yield USA  |  April 2015