Too much light?
 

I started growing in September of 2012 and was having trouble blooming things. I had one 4' 4 bulb T5 with seedlings and a couple of mature Brassavola nodosas under it. The B. nodosas bloomed. Everything else - dens, phals, oncs, pahps - were set way outside the rack with lights and did not bloom.

SO . . . recently bought 2 more 4' 4 bulb T5s and a big rack, and put EVERYTHING under it and the older T5. Now, some of my phals on the lower "medium height" level (for medium height plants, leaves about 6" from lights) are turning a weird rust color. Other phals do not seem fazed and the paphs seem fine. In addition, a species onc is turning orange. Does the weird rust color and orange color mean they are getting too much light now? Here are some pics. The upper rack - for "tall height" plants - seems fine: dens and oncs, mostly. The concerning ones are on that lower rack.

I really don't know. I gave my mini-phal very high light this summer, outside, and the leaves just turned very, very red. They've since faded now that it is just in the window. I don't have much experience growing under lights, though. I just have that one grow lamp and I'm thinking it doesn't put out enough light. I hope someone else can advise you.

6 in. is way too close. You're probably giving 3000+ foot candles of light. I keep my phals 15 in or so from the T5 bulbs and they could even be further away. Some show purpleing on the leaves. If you are taking plants from a low light situation you need to gradually increase the light. Start further away from the bulbs and every couple of days move them an inch or two closer until you get to where you think they should be. T5's with reflectors are pretty bright.

Bill

The influence of high temperature inside the leaf tissue might be more important than light intensity itself. Absorbed radiation is transformed into heat. I agree with billc. Your bulbs are close.

AND many look like they need a lot more water!

I also agree with Ray about the water. Paphs and Phals don't like to go as dry as some others.

Ray makes a good point. If you increase the light, the plant will need more water.

Bill, thanks for the specific information - I will try 15 inches. Yes, I know they should be gradually introduced to higher light, or any change, but . . . hmmm . . . the scientist/indolent person in me said "Let's see what happens if I just put 'em in there . . ." Actually, I found it interesting that some Phals reacted and some did not. They are all NoIDs. There must be some species that like a bit of a higher light. That's my "lay scientist" takeaway!

---------- Post added at 09:56 PM ---------- Previous post was at 09:52 PM ----------

Ray, tell me what you see about them needing water. I'm curious, because most of my Phals are in clear pots and their roots are always a beautiful green. They've been under these lights about 1 and 1/2 weeks. I feel like I've really gotten the watering down, but could be wrong! I need to see what you are seeing - I know you are an expert grower! Thanks!