Why LEDs make bad plant lights (facts + pics!)

[Kelo]

Are there links to the vids because I would be very interested to see them.

[littlefrog]

Littlefrog Farm LED

My videos kind of suck... But if you can get over that, there is probably useful information in there somewhere.

Rob

[Ray]

For those of you who are serious about LED light, check out the sevengens.com website, put together by Don Ellingham, and engineer with Phillips. Most of the folks involved in the discussion are looking at food crops, but we have a smattering of ornamentals stuff.

Of particular interest to me is the page outlining plant responses to specific wavelengths, which supports my opinion that "just" red and blue LEDs might be adequate, but probably isn't optimal..

[littlefrog]

Originally Posted by Ray

Of particular interest to me is the page outlining plant responses to specific wavelengths, which supports my opinion that "just" red and blue LEDs might be adequate, but probably isn't optimal..

Thanks for this, Ray. It is interesting. This also makes me wonder if plants from shaded environments might have different spectral requirements than full sun plants. After light travels through one or two layers of leaf canopy, would we expect it to be spectrally identical to full sun (just lower intensity)? I have no idea, but suspect not. Seems like an interesting experiment. I'd be surprised if there aren't some published data on this, although I'm not sure where to find it if there is.

I do have a fair number of fluorescent tubes in my plant room as well, so I might be getting enough 'spill-over' to compensate for anything that might be missing. I will be interested to see what happens after an entire growing cycle. I've also considered adding in a bank of fluorescent (or white LED) to the blue and red setup. I'd only have them on for the several hours a day I'm working in the plant room (mainly so I can see things in something approaching real color), but that might make a difference.

[Wjs2nd]

I have hydro grow LEDs. They are red, blue, green, and (I believe) infrared. My plants have a reddish glow but appear green and the flowers retain most of there usual color. Like some of the other posters, I don't know all of the science at work but I have bloomed two vandas among other orchids.

[Tsuchibuta]

Anybody know if there has been a cost analysis been done with LED's? I'm curious how long it would take to pay themselves off as they are still seem kinda pricey compared to standard florescent and CFLs.

[terryros]

It depends on your electricity costs and how many hours per day you run the lights. In some situations you can show a break even in a couple of years and after that you can be ahead. Obviously, the lower your electricity cost is per kilowatt hour the longer to the bread even point.

[Tsuchibuta]

Are they really that more efficient than CFL's or reg Florescent? The cost of the electricity per kilowatt wouldn't matter really, as I'm more concerned with the efficiency ratio since that could be translated to any energy cost. I'm sure in the long run LED's are potentially better since they would not have to be changed so frequently if at all. As they are advertised that they maintain output, I wonder though how true this really is since growing under them is a relatively new thing. If it means merely supplementation of wavelengths not yet achieved by the LED's themselves that still seems to be an improvement as you would only have to swap a few small bulbs instead of hundreds of larger ones. (in a large growing area)

I just remember a few years back an article in Orchids monthly that somebody did an analysis of growing orchids under lights or in a greenhouse and it pretty much came out a wash - (actually a little in favor of the light actually if I remember) I just wonder if in large scale if the same would be true.

[terryros]

Here is a link to a brief overview of LED lights from the Orchids Limited website.

OrchidWeb.com: Orchid Learning Center - LED Grow Lights

The initial upfront cost for a very large growing area is going to be high but if that capital is available, the investment would become good over a period of years.

I have 40 LEDs in my plant room now for 15 months and am able to bloom Paphs, Phrags, Phals, and have bloomed a few Miltoniopsis and Cattleya group specimens. I think it takes getting all growing conditions optimal to get good success and light is obviously one of these, but not the only one.

[billc]

Those LED Wide Spectrum lights look interesting. They seem more affordable than the others. One question in my mind is if you can't use a light meter how do you know how much light is hitting the leaves? I'd rather not cook my plants in finding out the correct distance.

Bill