I have to jump in here. I bought 6 LED bulbs from Orchid Web around 10mths ago, and they are around 2 1/2 to 3ft from my orchids, which are placed in a 1/4" thick glass sheet 4ft. long x 15"wide. I have a heat mat that fits that exact size on the glass, and a mirror again that size on that. My orchids are in S/H, and there is a small fan keeping the air moving. When I first joined this board, I had gotten info that the plants wouldn't do well unless I had the red and blue (disco !!) lights over them. I found it hard to believe that a company that specifies in orchid culture would sell bulbs that would not do the trick. My experience has been that these natural light and warm white LED's are just fine. I use 4 bulbs that are 7w, 38 degree cri of 80 , and 2 chip tec bulbs on the ends of the track. Go to that site and check out these bulbs. My set up is way way simpler than some I've read about here, and I have 4 different kinds of orchids all doing wonderfully. I hope I am not in trouble for mentioning where I got the bulbs...
