Quote Originally Posted by PurpleRoot
I know this seems like a stupid question, but how do I take the temperature of my grow room? I have two thermometers one on the wall (currently 78) and one on the lid of my hydro champer, with my plants under my light.... under the direct light it is approximately 87, in the shade on the same level it is reading 78..... my res temp is about 75.... I've had my thermometer under the light spike up past 100, while the wall temp was high 80s, I'm assuming that the reading under the light obviously should be higher then room temp? what temp should you attempt to keep under direct light? 400w mh approximately 14" from plant tops....
Well, here's how I do it. I have a thermometer in the room (doesn't matter where, in my case its about 2 ft from the ceiling hanging on a wall). After the lights have been on for a few hours, take your hand and place it between the light and the top of the plant.....as close to the plant as possible with the top of your hand towards the light. If that temperature is comfortable for you, it will be comfortable to the plant. Then check the thermometer. If it says 75F, say, then whenever it climbs over that you might want to change something, like bringing in more cold air etc. My thermometer actually also tells me the humidity in the room as well as the MAXIMUM and MINIMUM temp it has reached within the last 24 hrs,

keylime