Ceramic metal halide grow

[Steve83]

I just set up a 5'Lx2.5'Wx6.5'H under a 315w cmh, and would like to share what, why, and how I'm doing things, with hopes of learning more about orchids.

I decided to try a 315w cmh for the spectrum, cri (I found a tent with viewing panels), and the heat-to provide a day/night swing. In addition I chose a unit with the ballast in the hood, as opposed to outside of the tent.

I spent the latter part of the afternoon adjusting vents, light height, fan, and taking temp and humidity readings.

Oddly, my best temp and humidity readings so far were with all of the lower vents shut, minimal venting at the top, and the clip on style fan positioned high up, and blowing against the opposite wall to create light turbulence throughout.

I will post my high/low temps and humidity once it has sat like this for a few days.

Of note, having the lower vents open pulled air in and created a strong chimney effect, which in turn dropped humidity. I thought this would be needed to mitigate heat, but it made no difference. This was confirmed via probe 24" directly below the center of the lamp. Most info about cmh suggests a distance of 2.5' to 3' from the canopy, but that info is likely geared to marijuana growing. So, I have my plants a bit further and shrouded with burlap while they acclimate.

I hope to post more info in a few days, in addition to figuring out how to post pics.