Curious thing is I think Whazzup and Weezard mostly agrees with each other, but they look at the topic with different perspectives.
I do mostly agree with Weezard when we talk with the perspective of a small grow for self consumption. In this situation, spaces used are small, usually cold is not an issue, yield requirement may vary from one grow to the next without being a huge problem, and cost may be inexpensive enough compared with other alternatives. In this situation, LEDs works great and I agree complex color mixes are not necessary ( although it dont mean it cant be used to improve results, just that a simple red+blue may work and that blue, white and red definitively works fine).
I only disagree with him about LEDs used. I select LEDs by calculating their efficiency (uE emitted per watt burned) and cost (price per uE emitted). Actually, LedEngines are not good at either of both parameters, although the price may vary depending how and where you source them, of course (so for somebody, LEDEngin may have a better uE/price).
I completely agree Whazzup when I look the topic from a wider perspective. At current prices of LED lighting, in general advantages of the LED lighting not seem enough to compensate the extra cost. It is not that high power LED lamps working as big HID can't be done, but their cost would be too high to be interesting for targeted costumers, so nobody does it. 2-3 years ahead, who knows.
Spot-on! We are in full agreement here!
For the moment, only applications for LED lighting in the greenhouse markets are for situations of low light levels (seedlings and in general, very young and small plants), plant species grown for their leafy material (lettuce), and special situations. One application that may spread well is intracanopy lighting (or just, interlighting), as low temperature, solid LEDs are ideal for doing it and many crops benefits of it (included ours)
But I think main problem is price, and not the possibilities of LED lighting for horticulture in general. And the price problem will disappear on a near future.
Light quality is often noted as a drawback of LED lighting for horticulture. I strongly disagree with this. LED lighting allows to tune the spectrum exactly to fit the exact requirements of each situation. Both when close to sunlight spectrum is required or when a very different one offer advantages. But obviously, it requires to know what spectrum is better on each situation, and that knowledge is what we lack. Each plant specie is different, and into each specie, different cultivars (strains) may react different, too.
An important observation!
In my own, sloppy, way, I'm working on this.
Have obtained a strain that does poorly under fluorescent light.
I'm attempting to "talk color" to it.
I devoted most of my research to this topic, as currently there is more that we dont know about than we know for sure.
For cannabis, we are narrowing down the spectrum that works better, at least for whole grows. Except for the UV range, we know decently what we need to use, and how to vary attending to different situations. Now we need to find optimal spectrums for each stage of development and situations as well as "tricks" allowing to affect some traits by lighting manipulation. I think possibilities of LEDs on this are really huge and severely under researched. Blast of light of narrow wavelengths or combinations of narrow wavelengths for short periods of time have the potential of strongly affect outcomes.
Just an example: could strong blue light blasts affect in a similar way than UV? (I suspect so). Either a pair of hours a day, maybe blasts during three days each 15 days, or at the mid of veg period, then after flowering induction and finally at ripening, etc. Possibilities are almost endless. Or, does a blast of very narrow UVB (290 +-5nm, for example) have a different effect or intensity response that wide UVB or UVB+UVA irradiation?
@weezard: I'm not privileged to share just any research data on a public forum as I explained to you in pm.
O, K.
But rest assured: I will no longer post any "dazling deflections" for you, sorry for even sharing them and bringing them up. Wow, you do know how to appreciate observations and information. You will probably disagree but hey, that's your good right .
Not at all, brah.
I told you that I enjoyed and appreciated your efforts.
They just didn't address my question.
If you can't share, you can't share.
I'll accept your excuse, and thank you again
Specific UVC radiation has a germicidal use which is even patented by a company called Cleanlight. It is a very successful method to fight powdery mildew. The dosage however is very low, application daily. (and yes I have tested that as well wearing goggles and gloves )
Again.
Not news my brother.
And has nothing to say to the UV/THC connection question.
But Thank you.
@knna: I totally agree that LED's are very useful for steering light as you can completely control the spectrum. LED has put photosynthesis research is a higher gear because it is now very easy to get very small bandwidth light.
Interesting thread, I cant believe I've missed it this long...
I'm thinking about scaling up my Led pc case (https://www.icmag.com/ic/showthread.php?t=218056) to a closet/ growtent size and have been contemplating building a light using only white Cree XP-G leds of R5 and Q5 bins. Looking at their data sheet http://reefledlights.com/wp-content/uploads/2011/04/xlampxp-g1.pdf The graph of their relative spectral distribution shows nice spikes in both 450 625 range as well as as filling in the green/orange range.
I'm wondering if this the most pragmatic approach or if I'd still be better served by using only targeted Led wavelengths, 455, 625, 660 and cool white? I know my eyes would appreciate the white light, as opposed pink purple eyestrain but that isnt really much of a justification. So what do you guys think?