Light levels for orchids.

[bil]

Has anyone got a list, or a link to a list of light levels for orchids please??

I'm looking for something fairly detailed and comprehensive, not the usual somewhat casual quantities. My photo app will give me lux, but fc is fine as I can always translate one to the other.

Any ideas would be much appreciated.

[wisdomseeker]

Most (orchid) light level suggestions are usually for a specific orchid.

They may, or may not be, good suggestions (working out well for one grower, but not working out so well for another grower). But, at least those recommendations can be a starting point for an unknown.

I mention "unknown" because there are different ways to measure light levels (and/or light intensity). Example: fc. Foot-candle measurements are much better at analyzing light intensity than using your "eye" to estimate light levels for plants. Even though foot-candles are an acceptable measurement to many, an instantaneous fc measurement does not take the day length into account.

This is a good site IMO [orchidboard.com] for asking opinions on what light levels work best for a particular orchid. I'm sure you will get some very good suggestions from both hobbyists and professionals, alike. Opinions will vary, and I do not believe any OB member will purposely steer you in the wrong direction. They're just sharing what works successfully from their end.

Since you mentioned foot-candles (being an okay light measurement for you)... a website that gives some good suggestions for lighting in fc may be of help (if you can locate the species that you are looking for):
Andy's Orchids - Species Specialist - Alphabetical Genus search(A).

Late note: Notice "Species Specialist" in the link mentioned above. The word 'specialist' could have easily been replaced by 'expert', but it was not. I like that a lot! This tells me that this particular 'specialist' realizes there is always something new to be learned within the expertise of their speciality.

[rbarata]

Hello Bil, glad to see you again around here.

See this one and this one.

[bil]

Hi rbarata, yeah still around.

Thanks for the suggestions, if anyone else has any that would be great.

[Ray]

Originally Posted by wisdomseeker

Late note: Notice "Species Specialist" in the link mentioned above. The word 'specialist' could have easily been replaced by 'expert', but it was not. I like that a lot! This tells me that this particular 'specialist' realizes there is always something new to be learned within the expertise of their speciality.

A nice thought, and correct I’m my mind, but the term “species specialist”, in this case, merely means they specialize in species, not hybrids.

[wisdomseeker]

Yes indeedy ~Species Specialist~.

Any suggestions for the OP in regards to recommended light levels of orchid hybrids?

[Ray]

Originally Posted by wisdomseeker

Any suggestions for the OP in regards to recommended light levels of orchid hybrids?

Yes.

1) For artificial lighting, the intensity should be no more that 50-55% of what various guides give for recommendations. In other words, if the AOS culture sheet recommends about 3500 fc for cattleyas, that is the peak, noontime intensity to which it should be exposed, meaning the average will be lower (Read this)

2) Try to think in terms of PAR and PPF. Particularly the concepts of flux and volume of light received.

FC and LUX are measures related to the light sensitivity of the human eye, not plants.

[bil]

Originally Posted by Ray

Yes.

1) For artificial lighting, the intensity should be no more that 50-55% of what various guides give for recommendations. In other words, if the AOS culture sheet recommends about 3500 fc for cattleyas, that is the peak, noontime intensity to which it should be exposed, meaning the average will be lower (Read this)

2) Try to think in terms of PAR and PPF. Particularly the concepts of flux and volume of light received.

FC and LUX are measures related to the light sensitivity of the human eye, not plants.

Ray, can you expand on PAR and PPF please? I can get DLI and ppfd on this app

[Shadeflower]

these phone apps only measure the light the human eye can see. They are not designed to measure plant light nor can they be used as an infra red or heat sensing camera either.
So in terms of comparing lights for plants these phone apps are useless. I have used a phone app to compare my lights and the values might have been correct in human perceived light but based on the numbers some of my best lights would be no good.

I know it isn't very scientific but my approach is to see what they can tolerate. It might create a little bit of sunburn here or there but it gives you a better idea of the maximum the orchid can handle. Most of the time orchids will develop some physical changes to their leaves before they develop sunburn so it is very rare for any of mine to really get burnt bad. Unless I were to move it to a sunnier spot and go away for a week.

Orchids are generally low light, medium light or high light growing so once you know the level of one (through a bit of trial and error) then it is easier to judge how much to use for the rest.

Or get a quantum par meter.

now you might say hold on a quantum par meter is 10 times more expensive than a lux meter and 100% more expensive than a free phone app but there is a reason for it, because nothing else can do the same job accurately.

A lux meter mainly measures green light. The value you get might be meaningful, it might not be because plants hardly absorb any green light at all. A free phone app will be even less reliable in its accuracy.

If measuring a blue and red light I think the lux value would be really low so you might think so stick the plant really close but the lux value will be low because a red and blue light will be emitting no green but enough red and blue to fry the orchid.

edit:

[Ray]

Originally Posted by bil

Ray, can you expand on PAR and PPF please? I can get DLI and ppfd on this app

PAR - Photosynthetically Active Radiation - is simply referring to all the wavelengths between 400-700 nm.

PPF - Photosynthetic Photon Flux - is the rate at which photons in the PAR range are striking the plants. PPFD is the density of those, expressed in micromoles/square meter/second.

DLI - Daily Light Integral - is the sum of all PAR photons received over the course of a day, and that is probably the most important factor, and most universal, as it applies to any type of light source. Finding a reliable DLI range for orchids is difficult, unfortunately, but is improving.

Shadeflower’s last few paragraphs are a great, practical example of the concept.

A very rough conversion from sunlight foot-candles to PPFD is 0.200, meaning that a recommended 1500 FC would be equivalent to 300 micromoles/sq m/sec, but we cannot forget the fact that - again - that is the peak, noontime PPFD, and the Sun’s intensity goes from zero to max to zero over the course of the day.

If we take the average to be half that, then multiply by the time (12 hours are 43200 seconds), our DLI becomes 150 x 43200 = 6480000 micromoles, or 6.48 moles of photons.

So, I suppose that a very general way to convert (peak) FC recommendations to DLI would be FC x 4320 = DLI