LED Efficiency: Red/Blue vs White

[PetFlora]

There is much confusion regarding light efficiency.

I know I mentally labored over the spectrums I chose for the BML SPYDR 600, thinking I might be overdoing the blue spectrums, but it flowered quite well
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Below is paraphrased from conversations with the owner/designer of Solar Spec LED panels.

I should have a SS 100 and a 260 within 2 weeks

The McCree curve tells us everything u need to know about the PAR spectrum.

Plants are very efficient at what they do to conserve energy for their main priority, which is to flower, fruit, or producing seeds.

(Me) While I agree, the 3000K only COB diys are vegging nicely, with minimal stretch

If you're talking about just growth then yes, because u only need ~8-10% blues. The thing is blue also acts similar to uv-b in stimulating resin production. Blue will also boost photosynthesis since it sets the pace for the reds to follow. Why not set a fast pace?

Yeah, they might be vegging ok, but they also don't have anything to compare to for those grows, right? Are any of them comparing it to another spectrum say like mine, which is a more balanced, and tune spectrum vs. a single band spectrum.

I can guarantee, a multi-band spectrum with more blues and green will out veg and flower it (3000K) all day long. You have to remember vegging is very important since it establishes the platform on which flowering will take place. At high intensive apps like ours, green is (as much) a priority as reds and blues.

Red is used mostly by the upper canopy, while the intra-canopy relies on the blue and green since they penetrate the canopy better than other bands. The light spectrum the intra-canopy receives is totally different, and closely resembles to what underwater plants get due to the weaker bands being filtered by the canopy and water. The reflected and diffused light contains mostly blue and green, since the other weaker bands are filtered by the canopy.

Because of this, plants have learned how to effectively use blue and green light in shaded region of the plant. This is a fact that's completely overlooked by most of the makes, with exception of a few, mostly the white ones.

hth
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[mangroef]

Maybe that means that it would be good to place red led at the top and blues at sides from the plant?

 

[cocogrower]

Maybe that means that it would be good to place red led at the top and blues at sides from the plant?

I've had the same thought, a few 6500k bulbs hanging in the lower parts of the canopy..

 

[PetFlora]

I've had the same thought, a few 6500k bulbs hanging in the lower parts of the canopy..

It's the reds that don't penetrate deep

 

[magiccannabus]

I've surrounded my plants with daylight(6500K) fluoro tubes and I observed an almost completely suppression of stretch. Even sativa dominant plants that normally would stretch 2.5-3 times their height instead would only stretch about 20%. It can be useful when you have limited space, but it may also have some downsides. I had many hermie problems during that time, but its hard to say if the light spectrum had any bearing on that. Flowering sure did seem to take a lot longer too though.

 

[cocogrower]

It's the reds that don't penetrate deep

Far red penetrate more than red and send a signal to the plant that it is shaded, and therefor need to put in an extra gear, growth wise. Ratio of red and deep red plays a role here i believe.

According to the abstract of this article blue light has the opposite effect: http://journal.ashspublications.org/content/126/3/275.full.pdf

Also in some plants green light seem to stimulate stem elongation:

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC519058/

The studies are not made on MJ but I've red thees findings in so many different articles that i believe it applies to most plants that like intense light.

 

[cocogrower]

I've surrounded my plants with daylight(6500K) fluoro tubes and I observed an almost completely suppression of stretch. Even sativa dominant plants that normally would stretch 2.5-3 times their height instead would only stretch about 20%. It can be useful when you have limited space, but it may also have some downsides. I had many hermie problems during that time, but its hard to say if the light spectrum had any bearing on that. Flowering sure did seem to take a lot longer too though.

How much was your flowering delayed? I'm currently growing under a mix of 5000k 6000k 630nm 660nm and blue. So very little to no far red at all.. A few of my strain flowered as described by the breeder, but a few of them seems as they will never stop..

I've limited height, so the holy grail for me is to find a spectrum that suppresses stem elongation but still triggers the onset of flowering and an abundance of flowering. Or wait, do others want he same?

 

[Bubbleblower]

I like how he looks at the spectrum in a 3-dimensional way. He is right about the green too, it acts as a supporting pigment and is very important for the morphology of the plant. Also if I remember correctly at higher intensities -like we have- it gets more efficient. We know leafs use sunlight 95% efficiently, so may be there are other action curves we have no idea of.

The McCree curve tells us everything u need to know about the PAR spectrum.

It's surprisingly accurate for cucumbers or tomatoes, but not so much for cannabis. Also photosynthesis isn't the only important process that takes place. We probably shouldn't worry too much about it though, the plants photo adept to any light as long as it is not too extreme.

 

[PetFlora]

I've surrounded my plants with daylight(6500K) fluoro tubes and I observed an almost completely suppression of stretch. Even sativa dominant plants that normally would stretch 2.5-3 times their height instead would only stretch about 20%. It can be useful when you have limited space, but it may also have some downsides. I had many hermie problems during that time, but its hard to say if the light spectrum had any bearing on that. Flowering sure did seem to take a lot longer too though.

Some 6500 is vg, however, I THINK 5000 would be a happy medium between stretch and elongation

Some DIYers are actually growing bushes using only 3000K Cree COBs

 

[Bubbleblower]

a spectrum that suppresses stem elongation but still triggers the onset of flowering

IMO you were heading in the right direction.
Adding blueish broadband intracanopy light would get you exactly that if you also add some FR at the end of the lightcycle.

In nature not much red gets through the canopy, only blue. The inverse square law has no effect there, but has a big effect in the room, that's why you need mainly blue light for intracanopy (of course some red as well doesn't hurt).


Here is the info on the green light:

Green Light Drives Leaf Photosynthesis More Efficiently than​

Red Light in Strong White Light: Revisiting the Enigmatic​

Question of Why Leaves are Green

 

[magiccannabus]

How much was your flowering delayed? I'm currently growing under a mix of 5000k 6000k 630nm 660nm and blue. So very little to no far red at all.. A few of my strain flowered as described by the breeder, but a few of them seems as they will never stop..

Well with the grow that I did entirely with side-lights, out of 16 of the 32W tubes, 4 were 3000K and the rest were 6500K(512W total on 2 sq ft.). Flowering was definitely delayed more in some plants than in others. My Trainwreck x Sour Diesel just kept growing and adding on more flowers until it finally hermied and it really never completely finished even after 80 days. I ended up chopping them because of it. The Trainwreck X Columbian Gold was also delayed but not nearly as much. It got closer to finishing than they did.

Later on I went to a 400W CMH overhead and 256W of surrounding fluoros. Again the plants never quite wanted to finish. I also had an AC failure which was causing problems, and I think maybe the CMH didn't love my ballast. I ended up switching to my regular HPS bulb after 60 days and a week or two after that they finally started to swell up properly. Heat forced me to cut them before they were totally done, but they got pretty close to ideal but the yield was awful for the space and power I used.

I strongly suspect that the lower amount of far red in the CMH and the near total lack of it in the fluoro tubes was detrimental to flowering, especially when they were getting so much blue. If I had to guess I'd say 60-70 of the light they were getting was in the blue spectrum. With the HPS that balance totally changed and I think it made a big difference. The short time I vegged them in the flowering chamber under the CMH and daylight tubes was awesome, but once I switched to flowering their performance really tapered off. This is not to say anything bad about CMH, I just think I vastly oversupplied the plants with blue light for flowering.

 

[cocogrower]

Well with the grow that I did entirely with side-lights, out of 16 of the 32W tubes, 4 were 3000K and the rest were 6500K(512W total on 2 sq ft.). Flowering was definitely delayed more in some plants than in others. My Trainwreck x Sour Diesel just kept growing and adding on more flowers until it finally hermied and it really never completely finished even after 80 days. I ended up chopping them because of it. The Trainwreck X Columbian Gold was also delayed but not nearly as much. It got closer to finishing than they did.

Later on I went to a 400W CMH overhead and 256W of surrounding fluoros. Again the plants never quite wanted to finish. I also had an AC failure which was causing problems, and I think maybe the CMH didn't love my ballast. I ended up switching to my regular HPS bulb after 60 days and a week or two after that they finally started to swell up properly. Heat forced me to cut them before they were totally done, but they got pretty close to ideal but the yield was awful for the space and power I used.

I strongly suspect that the lower amount of far red in the CMH and the near total lack of it in the fluoro tubes was detrimental to flowering, especially when they were getting so much blue. If I had to guess I'd say 60-70 of the light they were getting was in the blue spectrum. With the HPS that balance totally changed and I think it made a big difference. The short time I vegged them in the flowering chamber under the CMH and daylight tubes was awesome, but once I switched to flowering their performance really tapered off. This is not to say anything bad about CMH, I just think I vastly oversupplied the plants with blue light for flowering.

Nice to hear about your experience with white/side lightning MC! Did you ever complete a run with HPS from above, and cold tubes on the sides? I only have experience with HPS (son-T agro) and Chinese leds of the mentioned spectrums. I have not flowered exactly the same strains, or under the same conditions. But my impression is definitely that HPS made the plants flower faster.. But here light intensity might have come to play as well. around 2000 l/sq feet compared to 7400 l HPS.. In my next run i will try close to 7000 l/square feet of Led and see what that makes with my plants..

What do you guys reckon is the optimal light intensity for short and squat plants? 12/12 from seed it is..

 

[HydroGrowLeds]

Here is a great read I thought I would share with you:

https://docs.google.com/file/d/0B5gZ0gCb1nrWRXA1RDlUS3dtTUk/edit

It's going to blow your mind and explain to you exactly why Hydro Grow uses the spectrum we do.

 

[tenthirty]

Somewhat misleading and not quite accurate IMHO. It also does not go into efficiencies of shade adapted plants vs sun adapted.
Nor does it take into account photomorphology.

SDS explored the concept of the "perfect spectrum" on another forum in a much more in-depth manner and specific to cannabis.

McCree action spectrum
http://www.controlledenvironments.org/Light1994Conf/1_3_Tikhomirov/Tikhomirov text.htm

Planckian locus
http://en.wikipedia.org/wiki/Planckian_locus

Google KNNA and goldy Lox spectrum.

 

[cocogrower]

Here is a great read I thought I would share with you:

https://docs.google.com/file/d/0B5gZ0gCb1nrWRXA1RDlUS3dtTUk/edit

It's going to blow your mind and explain to you exactly why Hydro Grow uses the spectrum we do.

Sounds interesting, but speed reading didn't really give me any answers. Scientific English is a bit hard for me to grasp at this hour..

Hydro: What did you learn from it?

 

[cocogrower]

Somewhat misleading and not quite accurate IMHO. It also does not go into efficiencies of shade adapted plants vs sun adapted.
Nor does it take into account photomorphology.

SDS explored the concept of the "perfect spectrum" on another forum in a much more in-depth manner and specific to cannabis.

McCree action spectrum
http://www.controlledenvironments.org/Light1994Conf/1_3_Tikhomirov/Tikhomirov text.htm

Planckian locus
http://en.wikipedia.org/wiki/Planckian_locus

Google KNNA and goldy Lox spectrum.

TenThirty, think i've been sniffing on that SDS thread earlier, but now found some really informative parts; like how length of days affects hight of sativas and hybrids. Thanks!!

 

[magiccannabus]

Nice to hear about your experience with white/side lightning MC! Did you ever complete a run with HPS from above, and cold tubes on the sides? I only have experience with HPS (son-T agro) and Chinese leds of the mentioned spectrums. I have not flowered exactly the same strains, or under the same conditions. But my impression is definitely that HPS made the plants flower faster.. But here light intensity might have come to play as well. around 2000 l/sq feet compared to 7400 l HPS.. In my next run i will try close to 7000 l/square feet of Led and see what that makes with my plants..

What do you guys reckon is the optimal light intensity for short and squat plants? 12/12 from seed it is..

I was about to try it with HPS from the start, and maybe turning on side lights maybe not. Then I had some friends get very dramatic about something and was too worried they were going to turn me in for something else(rescuing cats without a license...) so I scrapped the grow setup for a while. I've got 3 plants that are about 16-18 inches tall right now though and I am going to stick them in the flowering chamber as soon as I can get that room ready again....

 

[Bubbleblower]

Well with the grow that I did entirely with side-lights, out of 16 of the 32W tubes, 4 were 3000K and the rest were 6500K(512W total on 2 sq ft.). Flowering was definitely delayed more in some plants than in others. My Trainwreck x Sour Diesel just kept growing and adding on more flowers until it finally hermied and it really never completely finished even after 80 days. I ended up chopping them because of it. The Trainwreck X Columbian Gold was also delayed but not nearly as much. It got closer to finishing than they did.

Later on I went to a 400W CMH overhead and 256W of surrounding fluoros. Again the plants never quite wanted to finish. I also had an AC failure which was causing problems, and I think maybe the CMH didn't love my ballast. I ended up switching to my regular HPS bulb after 60 days and a week or two after that they finally started to swell up properly. Heat forced me to cut them before they were totally done, but they got pretty close to ideal but the yield was awful for the space and power I used.

I strongly suspect that the lower amount of far red in the CMH and the near total lack of it in the fluoro tubes was detrimental to flowering, especially when they were getting so much blue. If I had to guess I'd say 60-70 of the light they were getting was in the blue spectrum. With the HPS that balance totally changed and I think it made a big difference. The short time I vegged them in the flowering chamber under the CMH and daylight tubes was awesome, but once I switched to flowering their performance really tapered off. This is not to say anything bad about CMH, I just think I vastly oversupplied the plants with blue light for flowering.

This is a great post, no theory, but facts (KNNA style)

May be we shouldn't try to reinvent the wheel too much but go with what's known to work. Why trial and error if all these errors have already been made. Others with resources we can only dream of are doing all the work anyway, for example at the WUR and it's driving them crazy.
They make "perfect" spectrums that in theory should be X% more efficient than regular light, but in reality it never is. Every tiny little change they make effects everything else and sometimes dramatically. Temperature and CO2 levels also have a big impact on the effects of spectrums and changes of it as well as different light cycles, humidity, etc, it's all very multivariate analysis. Never in our life will we figure out how plants really work, no matter what led companies claim, it is just not that simple.

One thing by the way that is known to work is using intra canopy light, but very little of it.

 

[greengenes707]

We know leafs use sunlight 95% efficiently, so may be there are other action curves we have no idea of.

How do we know this?

 

[magiccannabus]

Photosynthesis actually only catches from about 0.1% to 2.0% at best. Its incredibly inefficient. If it could capture 95% of light, the plants would look very dark! Most of the sun's light either bounces back into space or becomes heat.