Rays LED lights and light meter measurements

[naoki]

Joe, there are some literatures about how orchids respond to amount of light. It is dangerous to say only a part of the story because environment (temp, RH, watering frequency) has a large effect on optimum irradiance. But without getting into details, one study showed that Paphiopedilum photosynthesis saturate around 100-150micromol/m^2/s (i.e. above this level, you don't get higher rate of C assimilation). For Phalaenopsis, one study show that saturation is around 180 micromol/m^2/s.

https://www.researchgate.net/publica...nopsis_Hybrids

If you are interested in the Paph study, I can probably find the citation.

So even Phalaenopsis can handle moderate amount of light. Now, this is the maximum amount, and most likely we can't keep them in the best condition. In this case, the extra light becomes waste of energy. So each person would set what would be the good balance between the cost and growth of plants. I decided about the half of the maximum capacity sounds good to me (trying to think that light isn't the limiting factor, which is usually the case with indoor growing). Ray has grown at the lower amount, and they can grow and flower. So from the experience, the minimum amount can be as low as Ray's (30 micromol/m^2/s). Also if you go to the link I posted earlier (or it could have been another thread where we discussed this), TerryRos showed that he can grow orchids at a fairly low amount of light under artificial light. So you can try out with high or low light, and see what would be good for your environment.

Also even within a genus, there could be quite a bit of variation. If you go to the link below, there is a table about this topic:
Cultivation of Palaenopsis
For example, P. amabilis and P. tetraspis are placed in the corner of my grow tent, shaded by other plants, but they grow and flower ok. I haven't been measured, but less than 50 micromol/m^2/s for sure. Growth can be faster, but they are already big, so I'm ok with slower growth.

Sorry, I don't have much experience with the intergeneric oncidium. But as winter girl said, it is probably higher than Phals. I think my Cattleya species are getting around 150-250 micro mol/m^2/s (I haven't measure it for a while, so I might be wrong about this). You can adjust the height of pots so they are closer to the light.

[terryros]

I agree with everything that Naoki said. I think the hard thing for me and maybe most beginners with LED lights, is learning to forget all the foot candle/lux numbers which are written about. Instead, we focus on the photosynthetically active radiation (PAR) in photon micromoles/m2/sec which Naoki is citing. I have an acceptable PAR meter to do these measurements that cost a little less than $150. In the numbers below I will leave off the micromoles/m2/sec units. Because we have constant light for the whole day, rather than the rising and falling daylight levels of the sun, we only need levels about 1/2 that of the peak that a greenhouse grower would need to get good growth.

I am getting very strong blooming of Phalaenopsis with a reading of only 50 at the top of the leaf zone. Phrags are blooming well with 70-80 at the top of the leaves. I bloomed several nobile-type Dendrobiums this winter with about 100 and have blooming Cattleyas with 150-200. My day lengths range from a minimum of 11 hours to a maximum of 13.5 hours.


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[smokinjoe52]

I like to think that I now have a PAR meter for $39. All I have to do is take the fc reading and multiply by "my number" and Voila...micromoles. I can do this because I know that Ray's LED lamps output 55 micromoles at 12" and my meter reads 315 fc, so my number is .1746. Doable with any lamp and any light meter if you know the details about the lamp like we do Ray's.

So essentially I am forgetting about lumens, lux, fc etc. I am just using an fc measurement to convert to the LED standard of micromoles. Even if I am off by +- 20%, at least I am in the ballpark. I had NO idea of light levels in the grow chamber prior to going through this.

Thanks to all of you for the information to help me "convert" my fc meter!

BTW - It's the DR Meter LX1330B from Amazon.

Joe

[Ray]

Joe, Phals are very adaptable, and thrive in low light.

The best ones I have ever seen were in a greenhouse that was so algae-covered and dark, that it took several minutes for the eyes to adjust when entering it. It was hot (95F) and humid (95% RH), and everything was blooming to the max!

30 micro-moles over 14 hours is roughly the equivalent of a peak natural daytime sunlight intensity of 500 fc, while the 100 level for 12 hours is about 1500 fc.

[smokinjoe52]

Ray,

Had to re-read this a couple times. I think what you are saying is that 30um of constant artificial light, is roughly equal to a PEAK daytime equivalent of 500 fc, across the entire 14 hour photo period for both sources.

Do I understand correctly?

Joe

[Motheroftwins]

Where did you buy the fixtures for your LEDs? I have the LEDs from First Rays but haven't found satisfactory fixtures.

[smokinjoe52]

These are the ones I used:

Amazon.com : LimoStudio 2 x New Studio AC Socket Light Stand Mount Umbrella Holder, AGG428 : Photographic Lighting Umbrellas : Camera & Photo

Keep in mind that they are designed to slip onto a 5/8" outside diameter tube. I am not sure how you would mount them otherwise. They are not ceramic, but at 13 watts, they don't even get warm.

Also, for headache prevention, these WILL NOT work.

Amazon.com : 100W Ceramic Heat UV UVB Lamp Light Holder for Chicken Brooder Reptile Basking : Pet Supplies

Ray's bulbs will not screw into the fixture far enough to make a connection. The black housing extends too far out from the socket.

Joe

[Motheroftwins]

Thanks Joe. Funny enough I did buy the Chicken Brooder fixtures... You are correct - didn't work.

[Ray]

Originally Posted by jbridge758

Ray,

Had to re-read this a couple times. I think what you are saying is that 30um of constant artificial light, is roughly equal to a PEAK daytime equivalent of 500 fc, across the entire 14 hour photo period for both sources.

Do I understand correctly?

Joe

If you consider sunrise to noon to sunset - with the light intensity zero to max to zero - as a triangle, then the area under the triangle is the "mass" of light the plant receives in a day. The area of a triangle is 1/2 base X height, so if you are going to place a plant under a constant light level for the same number of hours, then that intensity should be 1/2 of the peak intensity of the natural light.

I have seen recommended light levels for phalaenopsis, for example, to be 500- to 1500fc, so that implies artificial lighting from 250 - 750, and using Naoki's 0.14 factor, that's 35 to 105 micromoles.

[smokinjoe52]

Makes perfect sense. Thanks for the additional details.

Joe

---------- Post added at 01:15 PM ---------- Previous post was at 12:47 PM ----------

Sent you a PM on how to make the chicken lights work.