We do not see far red. The white shading could filter it out and we wouldn't be any the wiser. In filtering out the far red the shading would also filter out a lot of heat.
Yes, spectra affect growth. So does intensity.
spujr,
you have the light on for 20 hours? Doesen't that have a negative effect on the growth of the plants if they have a night period of only 4 hours?
You are right about CAM and I realize my crop examples in my post above are either c3/c4 types. So again, caution in the wind. I think skeptism is due, but I'm trying it anyways .I agree with Ray's position on this. Light intensity is the easiest variable to test and, all other arguments aside, should be the first thing tested. You can get a cheap luxmeter online if you don't have a smart phone that can support a lightmeter app like "lux light meter". The plants aren't crowded (mine are more crowded but I don't see this issue) so light spectrum would be the next hypothesis to test.
I don't think running the lamps for 20 hours is a good idea. The plants do need to rest, and as many orchids are (if I recall correctly) CAM plants they need that night period to prepare their metabolism for the next day. Perhaps Naoki can weigh in once we have the lux meter readings?
I grow under LED tube lights and adjust the daily light interval from 14 hours/day in May to 11 hrs/day in November. It is a gradual change of 30 min/day from month to month. Max/min temps in the room are adjusted accordingly as well. From what I’ve read longer light interval does not make up for insufficient intensity.I agree with Ray's position on this. Light intensity is the easiest variable to test and, all other arguments aside, should be the first thing tested. You can get a cheap luxmeter online if you don't have a smart phone that can support a lightmeter app like "lux light meter". The plants aren't crowded (mine are more crowded but I don't see this issue) so light spectrum would be the next hypothesis to test.
I don't think running the lamps for 20 hours is a good idea. The plants do need to rest, and as many orchids are (if I recall correctly) CAM plants they need that night period to prepare their metabolism for the next day. Perhaps Naoki can weigh in once we have the lux meter readings?
My bulbs with the 11-14 hr daily light interval (referred to in the reply below) are 5,000k. Here are my specs.One of the reasons I asked Phred earlier which bulb model he is using is because there is a big spectrum difference between the 2700k and 6400k (both are 48" 54W):
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I am not familiar with these types as I use something different but it appears the 6400 has almost no red spectrum.
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My bulbs with the 11-14 hr daily light interval (referred to in the reply below) are 5,000k. Here are my specs. View attachment 15745View attachment 15746
That would more closely resemble natural daylight, I think (with noon being the most intense part of a sunny day) which is when the recommended Foot Candles for each type of orchid are measured. I’m not sure of the benefit, though. It was recommended (and I’ve found) with my lights, that with the constant light for the entire duration of the daily light interval, one-half the recommended Foot Candles for each type of orchid is what is needed. That enables me to raise the lights to 24-30” above leaf canopy which is glorious headroom (with 3 tubes in each fixture over Catts and 1 tube over Paphs and Phals. I can’t tell you the foot candles, but it it really low (relatively speaking) because I measure PAR, but everything is growing and blooming well (except for the catts I repotted at the wrong time when I was still learning). But, they are coming back with new leads, so there is hope even when we mess up. Happy growing.I have a similar light setup using the 5600K model but @ 20W instead of 40.
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I am still learning about what all the numbers mean, but the nice thing is that this info is useful for my work application as well as my hobby (orchids)! I'm thinking it might be interesting to explore the different bulb types (3200K & 5600K) to artificially "mimic" a day, where the 3200K bulbs are turned on a few hours in the morning and late afternoon and then the 5600K turned on during the day. I suspect the effects would be minor in relation to plant growth but still fun to try.
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