Lighting an orchid closet - fluorescent or LED? Otherwise?

[littlefrog]

I wasn't trying to skew anything, I took the first number off the list of google results, and was working from numbers I actually saw when doing research on the best systems for my own use last fall. I find your attitude annoying. I'm trying to give useful information about pros and cons of both systems. I use both fluorescents and LEDs, and find advantages in both. I'm glad you have the time to correct my numbers, enjoy your superiority.

[naoki]

Thank you Rob for lots of insights about LEDs for plants!

So with your LED UFO light, how far do you put it from plants and what the coverage area (let's say the area where you can grow low-moderate light requirement orchids such as paphs)?

Also, I'm sure lots of people would be interested in your LED strip. What kind of coverage (reasonable for orchid growth) do you get? Maybe photos? I've heard Finnex Ray II is pretty decent (at the PAR level).

I think one of the advantage of LED is that there is a possibility that they can make the emission spectrum which imitate the photosynthesis action spectrum. So I'm more interested in the development of blue/red systems than white LEDs. After reading a little bit more about white LEDs, they use phosphor to create more white light. So the blue-end of action spectrum is generally well covered, but red end is a bit low (with cooler white LEDs). After looking at some of the available emission spectra, I don't think David's blank statement about all white LEDs or florescent lights are similar is correct. At the PAR level, they may be similar, but it is not quite same as effectiveness to photosynthesis (or at PUR level). Comparison between (or within) red/blue systems, and white LED systems (or any other systems) can be done with measuring the spetra and use the general photosynthesis action spectrum. Or the comparison at the plant level is even better with CO2 gas exchange system (like Li-Cor 6400) to measure photosynthesis rate, or set up experiments to measure the actual plant growth (which takes time).

[Ray]

Naoki (and anyone else interested), take a look at sevengens.com. It is a website for LED horticulture.

I have been communicating with Don, the owner, and they are finding that plants respond differently to individual wavelengths in some cases, which may lead to a greater productivity.

So far, the majority of their work is with berries and vegetables, but they are developing emitters and controllers that allow one to vary the spectrum to suit your needs.

Interesting stuff.

[littlefrog]

Originally Posted by naoki

Thank you Rob for lots of insights about LEDs for plants!

So with your LED UFO light, how far do you put it from plants and what the coverage area (let's say the area where you can grow low-moderate light requirement orchids such as paphs)?

Also, I'm sure lots of people would be interested in your LED strip. What kind of coverage (reasonable for orchid growth) do you get? Maybe photos? I've heard Finnex Ray II is pretty decent (at the PAR level).

I think one of the advantage of LED is that there is a possibility that they can make the emission spectrum which imitate the photosynthesis action spectrum. So I'm more interested in the development of blue/red systems than white LEDs. After reading a little bit more about white LEDs, they use phosphor to create more white light. So the blue-end of action spectrum is generally well covered, but red end is a bit low (with cooler white LEDs). After looking at some of the available emission spectra, I don't think David's blank statement about all white LEDs or florescent lights are similar is correct. At the PAR level, they may be similar, but it is not quite same as effectiveness to photosynthesis (or at PUR level). Comparison between (or within) red/blue systems, and white LED systems (or any other systems) can be done with measuring the spetra and use the general photosynthesis action spectrum. Or the comparison at the plant level is even better with CO2 gas exchange system (like Li-Cor 6400) to measure photosynthesis rate, or set up experiments to measure the actual plant growth (which takes time).

It is too early to tell on the LED strips what the optimal setup might be. I'm just now starting to use them. I hate to get too excited before I know they work.

There are some pictures (and boring videos) of my setup posted on my website, which might be more instructive... But for the UFOs, I have two configurations. One is lighting an area about 4' long by 5' wide, at about 2.5' above the plants. Under that light I grow my larger bromeliads and a lot of my potted tolumnias. A lot of phragmipedium as well. I was worried about the tolumnias, but they did well under that condition. Under another light with the same setup, I grow cattleyas and vandaceous (Ascocentrums, I don't really do vandas). Had really good blooming on all of that last year, and won the cattleya trophy again with my Tutenkhamun 'Pop', so something might be working.

That is high light, so 4x5' or maybe 5x5' for those types of plants. Of course I try to arrange the highest light plants in the middle, but cattleyas still bloom at the edges. The other configuration I use for the 90W UFOs is over my hanging plants. I have the lights mounted close to the ceiling, and the baskets hang from rods at about 6' high, so the lights are about 3' above the plants. Under all the baskets I have a bench which I put ferns and paph seedlings on. Three of the UFOs cover an area 60" wide by 14 feet long. High light stuff in the middle, foliage on the edges.

I think for paphs, depends on the types. I grow mostly maudiae and bulldog types, for those I would anticipate 6'x6' coverage at 3.5' would be good. If I grew many multiflorals, I'd put them in the middle of that arrangement, and the Maudiae types on the edges. However, I don't actually use UFOs for Paphs... I actually grow all my paphs under a different light unit, the 'Glowpanel 45' - it is a square unit. Three glowpanels per 8' bench (my benches are 30" wide), as high up as I can get them (2 feet?). That was completely awesome, I have not had that much fun growing paphs in many many years.

Third LED light i have is a 300W panel. That is overkill under any orchid circumstances, I think. Too expensive to recommend, so I'll skip it for now.

There is a lot of real science to do... Some of it is being done, but there is a lot of opportunity. I am not a plant physiologist, but I strongly suspect the optimal spectrum for orchids will be variable, but not based on taxonomic relationship. At different levels in the forest canopy one would expect to see different available photosynthetic radiation. Leaves and forest cover above the orchids will determine which wavelengths get through. Evolution being evolution, I would predict that the orchids under deep cover (forest floor) would be optimally collecting at different spectra than orchids under very little cover. I don't know enough to predict what that means in terms of spectra, but it is something I hope somebody looks at. I could be totally wrong, too, that is the beauty of a hypothesis.

[naoki]

Originally Posted by Ray

Naoki (and anyone else interested), take a look at sevengens.com. It is a website for LED horticulture.

I have been communicating with Don, the owner, and they are finding that plants respond differently to individual wavelengths in some cases, which may lead to a greater productivity.

So far, the majority of their work is with berries and vegetables, but they are developing emitters and controllers that allow one to vary the spectrum to suit your needs.

Interesting stuff.

Thank you, Ray. Yes, I have been following a little bit of his stuff. To be honest, electronics part is a little too technical for me, but I'm learning. You are right about the response to the light spectrum. For example, FR:R ratio plays roles in photoperiodism (initiation of flowers), and also etiolation. Some orchids don't seem to care about photoperiodism (maybe because they are in tropics, and always understory??). But it would be interesting to have LED with controllable spectrum.

Originally Posted by littlefrog

It is too early to tell on the LED strips what the optimal setup might be. I'm just now starting to use them. I hate to get too excited before I know they work.

I think for paphs, depends on the types. I grow mostly maudiae and bulldog types, for those I would anticipate 6'x6' coverage at 3.5' would be good. If I grew many multiflorals, I'd put them in the middle of that arrangement, and the Maudiae types on the edges. However, I don't actually use UFOs for Paphs... I actually grow all my paphs under a different light unit, the 'Glowpanel 45' - it is a square unit. Three glowpanels per 8' bench (my benches are 30" wide), as high up as I can get them (2 feet?). That was completely awesome, I have not had that much fun growing paphs in many many years.

Thank you very much for detailed info, Rob! Hmmm, I was probably using 90W UFO LED incorrectly (too close to the plants). I placed it about 2.5' from the canopy of multifloral paphs, and I was getting sharp borders between the central bright area (about 1' x 1'), which a normal lightmeter (Gossen Ultra Pro) reads around 900fc (and higher in the very center). Outside of it it sharply drops to 300fc or so. Obviously with red/blue type grow light (mine is 5-band), the fc value isn't quite comparable to other white light source. I think cool-white fluorescent light has about 22-27% usable spectrum. So if red/blue LED has close to 100% usable spectrum (I don't know if this is true or marketing gimmick). So does 250fc of red/blue grow light give similar photosynthetic activity as 1000fc of fluorescent? So probably I should have place it further to get dimmer light, but wider coverage. It is possible I got a wrong kind of UFO LED, which has more spot-like light pattern. Mine is from Hydroponics hut, which was recommended in marijuana forums. I guess they requires higher light, so they may prefer more focused design.

Growpanel 45 sounds interesting. I should check it out.

Originally Posted by littlefrog

There is a lot of real science to do... Some of it is being done, but there is a lot of opportunity. I am not a plant physiologist, but I strongly suspect the optimal spectrum for orchids will be variable, but not based on taxonomic relationship. At different levels in the forest canopy one would expect to see different available photosynthetic radiation. Leaves and forest cover above the orchids will determine which wavelengths get through. Evolution being evolution, I would predict that the orchids under deep cover (forest floor) would be optimally collecting at different spectra than orchids under very little cover. I don't know enough to predict what that means in terms of spectra, but it is something I hope somebody looks at. I could be totally wrong, too, that is the beauty of a hypothesis.

I'm not trained in plant physiology, neither, although I have published ecophysiology-type papers. I know some understory plants like Begonia has red-coloration underside of the leaves, and this is supposed to be one of the adaptation to what you are talking about (I forgot about the details, but the BBC video, The Private life of plants, talked about it). I thought that the chloroplast is relatively conserved among different taxa, but I should ask about this. But anyway, it's an interesting stuff.

[Ray]

Following Rob's speculation about understory plants - I don't know if they 1) need fewer photos, or 2) are more efficient at grabbing them, but I would think that they might have evolved to a slightly different spectrum. Light filtered through overhead vegetation certainly will be of lower intensity, but its spectrum ought to have shifted from reflection off of it.

[BioWheel]

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