Minimum required spectrum
Posted: Tue Feb 06, 2018 4:29 am
I have been looking into LEDs for growing and keep coming back to the same question. What minimum number of wavelengths are required to grow for the entire lifecycle?
I have seen videos on YouTube by some guy named Random Ryan that shows serious problems when he tried to grow cherry tomatoes under a white LED light vs a no-name two color blurple LED light. The blurple light started out competitive but ran into serious problems as the plant moved from the small shrub stage into more of an adult veg cycle. His conclusion was that blurple is not as good as white LEDs. I would agree with his conclusions because the results he shows are quite dramatic. Although the experiment was quite excellent, he did not take it to the next step to determine what wavelengths are missing. In fact, he didn't even really describe the spectrum he actually got from either light. Great start but I had more questions than answers at the end.
I have also been reading about the Emerson effect that indicate the need for two colors of red (one above 680nm, the other below 680nm) are needed for best growth. This has been well documented since 1957 when it was first discovered. When I look at the spectrum for Samsung LM561C that everybody seems to like here, I find there is really very little power below 680nm.
So we get back to the original question of spectrum. What is the best choice for really excellent healthy growth? Does anybody have pointers to research done to find the four or five (or six or seven...) discrete wavelengths needed to achieve excellent growth? Ideally, it would also indicate the relative optical power levels for each color to optimize energy and LED selection. I would also be grateful for pointers to universities or labs that are looking into this area.
And yes, I'm one of those guys who thinks about all the various details on what could be possible. The more detailed the research, the better it is. I suspect the LM561C is a pretty good start but could be taken up a notch or two with the addition of a few extra colors.
And another question - Which color temperature on the LM561C is best? I am thinking the 3000K is best but I can't really find any comparative studies to show if this is correct or not.
-r2k
I have seen videos on YouTube by some guy named Random Ryan that shows serious problems when he tried to grow cherry tomatoes under a white LED light vs a no-name two color blurple LED light. The blurple light started out competitive but ran into serious problems as the plant moved from the small shrub stage into more of an adult veg cycle. His conclusion was that blurple is not as good as white LEDs. I would agree with his conclusions because the results he shows are quite dramatic. Although the experiment was quite excellent, he did not take it to the next step to determine what wavelengths are missing. In fact, he didn't even really describe the spectrum he actually got from either light. Great start but I had more questions than answers at the end.
I have also been reading about the Emerson effect that indicate the need for two colors of red (one above 680nm, the other below 680nm) are needed for best growth. This has been well documented since 1957 when it was first discovered. When I look at the spectrum for Samsung LM561C that everybody seems to like here, I find there is really very little power below 680nm.
So we get back to the original question of spectrum. What is the best choice for really excellent healthy growth? Does anybody have pointers to research done to find the four or five (or six or seven...) discrete wavelengths needed to achieve excellent growth? Ideally, it would also indicate the relative optical power levels for each color to optimize energy and LED selection. I would also be grateful for pointers to universities or labs that are looking into this area.
And yes, I'm one of those guys who thinks about all the various details on what could be possible. The more detailed the research, the better it is. I suspect the LM561C is a pretty good start but could be taken up a notch or two with the addition of a few extra colors.
And another question - Which color temperature on the LM561C is best? I am thinking the 3000K is best but I can't really find any comparative studies to show if this is correct or not.
-r2k