LED and BUD QUALITY

[Ca++]

Considering the colour they turn, they are probably more interested in blocking blue than red. Blue carrying twice the energy, and doing more harm than good in recent cannabis studies.

In other species, stress from bugs has bought out the colour, and bugs are less interested in the plants showing autumn colours. I don't think canna does this, but it's another reason that might exist.

 

[Prawn Connery]

Considering the colour they turn, they are probably more interested in blocking blue than red. Blue carrying twice the energy, and doing more harm than good in recent cannabis studies.

In other species, stress from bugs has bought out the colour, and bugs are less interested in the plants showing autumn colours. I don't think canna does this, but it's another reason that might exist.

If you're talking anthocyanins, they can can express as different colours depending on pH. But my theory on why they express as pinkish-red in cannabis under LED is due to the high amount of red light most LEDs emit, as well as the cyan gap.

Blue light is stronger, but red light has high absorption. Pink-red is also the complimentary pigment of cyan – which LEDs are notorious for lacking – so not all blues are equal, and any pigment change to reflect other colours (red, green, deeper blues and violet) to absorb cyan, which is not in abundance, would reduce light stress/photo-oxidative damage.

 

[Prawn Connery]

i just got 4.5 lbs from 2000 watts of homemade walmart leds.

but, why are people on this thread about LEDS and BUD QUALITY still comparing hid lighting to led lighting? there is a thread dedicated to that. why must it be done here contrary to the topic of the thread?

i know most of you mean well but this is not the place for that.

why can't the participants on this thread focus on improving the use of leds to improve the quality of their product?

either you can't resist the temptation to put down leds or you don't respect the thread topic and intent.

there are people here who really want to learn, why can't the rest of you simply let them do it?

editing to say that i understand comparing the different spectrums and the other factors involved with growth between the light sources but i don't understand those that are simply saying "hps for the win" or "leds are shit". this is not the place to express personal biases about which one is superior. there is already another thread for that. we are trying to improve the use of leds here, not argue about which lighting choice is best, this should be a simple concept to understand.

If I were to play devil's advocate here, one of the main reasons growers are reluctant to make the switch to LED is (an unfounded) fear of losing yield. Especially for those who are making money from their plants.

There is evidence that the increased amount of blue in LED (and in some cases violet and UVA) reduces yields, and that there is a trade-off between the red end of the spectrum that boosts dry yields compared to the blue end of the spectrum that increases quality (cannabinoids and terpenes).

What we're still trying to figure out is whether the correlation between yield and quality is caused by an increase in secondary metabolite production or a reduction in dry yield or a combination of both.

In other words, if you grow a 1kg plant with 10% THC under one spectrum while another produces a 0.5kg plant with 20% THC under a different spectrum (I am exaggerating for effect), then you still have exactly the same amount of total THC produced (100 grams). However, one plant will have higher yields and the other will have higher quality – so which do you prefer?

What I am starting to believe is that plants divert energy to either primary metabolite production (plant mass/yield) or secondary metabolite production (cannabinoids, terpenes) and that differences in spectrum can lead to photomorphogenic responses that cause plants to divert more energy to either one or the other.

The trick is to produce a spectrum that gives the plant the best chance to synthesise higher levels of ALL metabolites so that you can try to get the best of both worlds. Which is really my Holy Grail in terms of plant spectra.

 

[exoticrobotic]

it is about finding out what in hps caused the larger flowers that some leds are missing and how to supply that to enhance the production of your led-grown flowers. not to revert to hps just because you can't figure it out.

It is expensive figuring it out with leds when hps does it all already at a fifth of the price

Anyway...

I am sorry @Crooked8 saying you were up Bugbees arse but people are still experiencing increased plant colouring despite all other variables being the same when growing with leds.

Don't take it so personally bro it's not like anyone is talking about your leds or your plants ( they look amazing btw )

But plants are known to show increased anthocyanins due to their environment...That could be temperature or light spectrum.

You might not be experiencing an increase in anthocyanins with a $1700 a piece led light but a lot of other people, including me, are with the cheaper $600 home units

Why is this? someone asked a few turmultous pages back..Jeez, anyone would think this is a Haze thread

There are studies showing both blue and red light are effective in promoting anthocyanin accumulation.

There is also an interesting study talking about tomatoes with increased anthocyanins and the effects increased anthocyanins have on plant growth. -

limitation to photosynthesis
strong inhibition of side branching
increased branch-to-stem diameter ratio
altered leaf shape
reduced respiration rate

The study showed anthocyanins absorb light in the blue and red bands of the spectrum and develop traits of the shade avoidance response frequently observed in plants growing in the shade, ultimately leading to lower yields.

How do we avoid this with leds? Raise the lights? Buy your lights? Calmag? What?

I personally want to avoid the low yields/low growth rate/low potency of anthocyanin rich plants

 

[Prawn Connery]

I grow in soil found in growshop, usually some light mix where I add some bat guano. I don't flush neither I just give straight water for the last 10/15 days and I use some organic nutes, what was before the GHE organic line. I turn the light on during night time so when it's off it's daytime temps and it was around 22/25°c for the whole grow.
I should give more P or K to avoid this next time?

Honestly, your plants don't look that bad to me. They look pretty good. If it is only minor discolouration, I wouldn't worry too much about it.

But if you are concerned then, I noticed you defoliated a fair bit in that grow, and so one of the reasons the top leaves are showing more signs is that they are the few remaining leaves for the plant to draw nutrient reserves from.

Leaves primarily serve two functions: photosynthesis and nutrient storage. When you defol, you take away a source of nutrient reserve, as well as a source of photosynthesis. I have noticed that defoled plants tend to divert their energy into making larger leaves around the bud sites (harder to trim) to compensate, and that the buds themselves do not grow as big, because the plant has had to waste energy rebuilding its "solar panel" fan leaf network. You see this because heavily defoliated plants often look a little stressed.

A moderate amount of defol can be beneficial to allow airflow to prevent mould or allow a little more light penetration, so it has its place.

Defol aside, you could try adding a small amount of PK boost to your watering regime at around Week 4-5. I am talking fast-release mineral salts here. If you use a slow-release PK, like potash, you need to apply it a little earlier, near the beginning of flowering. I don't have a lot of experience growing in soil, so I'm not really an expert on soil formulas.

 

[Prawn Connery]

"Recently I grew some plants under Electric Sky V3, HLG 350R, and HPS . The HPS buds are great as usual. The Electric Sky buds are nice and aromatic, close to the HPS. And the HLG buds
are less aromatic and less taste but still pretty decent. It seems like the extra far red spectrum of the electric sky really did help the quality. Have you guys noticed similar results??"

Far red is where it's at, mate. I have never been a big fan of the HLG spectra.

The Electric Sky V3 spectrum is quite similar to the original high Light spectrum I developed six years ago.

Electric Sky V3

Original High Light (with a added violet/UVA).

Original High Light Vs McCree Curve

 

[Prawn Connery]

I am sorry @Crooked8 saying you were up Bugbees arse but people are still experiencing increased plant colouring despite all other variables being the same when growing with leds.

But plants are known to show increased anthocyanins due to their environment...That could be temperature or light spectrum.

You might not be experiencing an increase in anthocyanins with a $1700 a piece led light but a lot of other people, including me, are with the cheaper $600 home units

Why is this? someone asked a few turmultous pages back..Jeez, anyone would think this is a Haze thread

There are studies showing both blue and red light are effective in promoting anthocyanin accumulation.

There is also an interesting study talking about tomatoes with increased anthocyanins and the effects increased anthocyanins have on plant growth. -

limitation to photosynthesis
strong inhibition of side branching
increased branch-to-stem diameter ratio
altered leaf shape
reduced respiration rate

The study showed anthocyanins absorb light in the blue and red bands of the spectrum and develop traits of the shade avoidance response frequently observed in plants growing in the shade, ultimately leading to lower yields.

How do we avoid this with leds? Raise the lights? Buy your lights? Calmag? What?

I personally want to avoid the low yields/low growth rate/low potency of anthocyanin rich plants

This is a good post, but I want to point out that it is not always the case of seeing more colouration under LED vs HPS except in the context of higher (HPS) or lower (LED) ambient/leaf temperatures.

I see defoliation as the main contributor to anthocyanin response, and I think I see it more in LED because HPS tends to make plants stretch a little more which negates some of the need (or desire) to defoliate, and also because HPS has much more green light in it which is mostly reflected into the lower canopy where it is more even distributed.

This is my latest grow. I haven't defoliated at all. It is summer, so temperatures are warmer, and I use a high EC (2.4-2.6) throughout flowering, so there is little chance of nutrient deficiency and I try to balance my nutrient to ensure there is no lock-out, either.

There is very little colouration going on. The main plant showing it is the Sweetopia (Citral x Thin Mint Cookies) which does not like high light levels like the Haze and other plants in there, so it was the first to show a stress response.

Another grow with no real colouration

This is a friend's grow under my lights that show nothing, just normal green.

But here we have a plant (one of mine) that had a lot of internodal stretch that showed copious anthocyanin production as a stress response to all the light on the stems.

 

[exoticrobotic]

This is a good post, but I want to point out that it is not always the case of seeing more colouration under LED vs HPS except in the context of higher (HPS) or lower (LED) ambient/leaf temperatures.

Ok Let's try to narrow that down a bit.

higher (HPS) or lower (LED) ambient/leaf temperatures when lights are on maybe.

The increase in anthocyanins has been shown to increase leaf temperatures during middle of the day so may be the plant's response to low environment temperature with high intensity light.

This is solved with another heat source in the grow area?

or

i could use a hid.

 

[Prawn Connery]

Ok Let's try to narrow that down a bit.

higher (HPS) or lower (LED) ambient/leaf temperatures when lights are on maybe.

The increase in anthocyanins has been shown to increase leaf temperatures during middle of the day so may be the plant's response to low environment temperature with high intensity light.

This is solved with another heat source in the grow area?

or

i could use a hid.

LEDs actually do produce a lot of heat, except most of it is conductive/convective thermal transfer as opposed to radiant (IR) transfer. And given the same ambient conditions, the difference in leaf temperatures is minimal, as I showed with the Bugbee study. The difference in leaf temperatures actually narrows as ambient conditions get hotter.

BTW, anyone who knows me knows I don't have my head up Bugbee's arse – LOL! I have been quite critical of some of his methodology, but credit where it's due.

I fully agree that if you need metabolic warmth in your grow room, then use a HID. There are other ways to increase ambient temps inside a grow room or temp, but HIDs make sense if you also need the extra light.

Personally, I live in an area where it doesn't get that cold and my grow is inside the house, so ambient temps in my grow area are manageable and I don't have any real issues with low temps.

As far as anthocyanins increasing leaf temperatures, is it the anthocyanins increasing the temperature, or do increased leaf temperatures produce more anthocyanin? In other words, which one is cause and which one is effect?

On the subject of LED quality, I (honestly) have never heard someone switch from HID to LED (my LEDs, anyway) say they haven't seen an increase in quality.

We have done quite a few trials of LED vs HPS in the past. I have been trying to find photos of LED and HPS in the same room and these are the only ones I could find, as this room was replaced entirely with LEDs back in 2019 because the grower was so impressed with them.

So this is the finished LED grow that you can see on the left-hand side of the next photo

This is the rest of the room. The LED plants were a few weeks behind the HPS plants, so you can refer to the photo above to compare LED and HPS at the same stages of growth. As you can see, the LEDs more than rivalled the HPS with 2/3 the power. These are all the same strain (Paradise Seeds Wappa) being fed from the same nutrient reservoir. The aircon wasn't used. Note the LEDs on the left-hand side – same plants as above.

Here is an earlier LED trial grow in the same room with a different strain (Chimera's Mental Floss).

 

[kro-magnon]

Honestly, your plants don't look that bad to me. They look pretty good. If it is only minor discolouration, I wouldn't worry too much about it.

But if you are concerned then, I noticed you defoliated a fair bit in that grow, and so one of the reasons the top leaves are showing more signs is that they are the few remaining leaves for the plant to draw nutrient reserves from.

Leaves primarily serve two functions: photosynthesis and nutrient storage. When you defol, you take away a source of nutrient reserve, as well as a source of photosynthesis. I have noticed that defoled plants tend to divert their energy into making larger leaves around the bud sites (harder to trim) to compensate, and that the buds themselves do not grow as big, because the plant has had to waste energy rebuilding its "solar panel" fan leaf network. You see this because heavily defoliated plants often look a little stressed.

A moderate amount of defol can be beneficial to allow airflow to prevent mould or allow a little more light penetration, so it has its place.

Defol aside, you could try adding a small amount of PK boost to your watering regime at around Week 4-5. I am talking fast-release mineral salts here. If you use a slow-release PK, like potash, you need to apply it a little earlier, near the beginning of flowering. I don't have a lot of experience growing in soil, so I'm not really an expert on soil formulas.

Thanks for the reply, I was really happy with the plant in the picture I've shown but I wanted to understand the presence of the anthocyanin with a moderate climate. I tend to defoliate a bit more indeed since I switched to LED because it can be a bit extreme at some point of the flowering and my average humidity can quickly be too high.
I had a Sour Diesel in the same june grow who did not show any sign of purpling so if I understand what you're saying it's a good sign as she is not genetically prone to purpling, I had her more or less dialed as she was all green, I hope I'll ne able to replicate the result in my next run with this genetic.
So far I have been able to get 1G/w with a 465w LED panel, without reflective material on the side, what could I do to improve my yield if you don't mind? (I'll add reflective mylar rapidly)

 

[Crooked8]

It is expensive figuring it out with leds when hps does it all already at a fifth of the price

Anyway...

I am sorry @Crooked8 saying you were up Bugbees arse but people are still experiencing increased plant colouring despite all other variables being the same when growing with leds.

Don't take it so personally bro it's not like anyone is talking about your leds or your plants ( they look amazing btw )

But plants are known to show increased anthocyanins due to their environment...That could be temperature or light spectrum.

You might not be experiencing an increase in anthocyanins with a $1700 a piece led light but a lot of other people, including me, are with the cheaper $600 home units

Why is this? someone asked a few turmultous pages back..Jeez, anyone would think this is a Haze thread

There are studies showing both blue and red light are effective in promoting anthocyanin accumulation.

There is also an interesting study talking about tomatoes with increased anthocyanins and the effects increased anthocyanins have on plant growth. -

limitation to photosynthesis
strong inhibition of side branching
increased branch-to-stem diameter ratio
altered leaf shape
reduced respiration rate

The study showed anthocyanins absorb light in the blue and red bands of the spectrum and develop traits of the shade avoidance response frequently observed in plants growing in the shade, ultimately leading to lower yields.

How do we avoid this with leds? Raise the lights? Buy your lights? Calmag? What?

I personally want to avoid the low yields/low growth rate/low potency of anthocyanin rich plants

Please…..allow me to put my dukes down and swallow my pride…(achem)…quite the gulp there hah

Im like a battered man at this point. I love icmag so much almost out of nostalgia for what ive learned and shared here over the years. It feels like home. But, its gotten so combative with new people and trolls my patience has diminished.
-just know, i am here, for real, out of love and hope to learn and teach. I spend a lot of time giving back and i dont share bullshit. I share information i am truly confident in. My livelihood and career are reliant on this product.
-also know, i was firebreathing against led in 2020-2021. My fiancee fought me tooth and nail to make it make sense. A learning curve is an understatement. But i promise if you match the cardinal parameters you are setting forth you will win with led.

If you want to avoid a shade avoidance response i cant think of a better solution than led considering there is far less shade.

I DO see more coloration under led, from the strains that are more anthocyanin rich. But the ones that never produced any still dont under led. My question is, all things considered in my situation, we have more terps, cannabinoids, yield and overall health even with more coloration. So whats the problem? Where is the link in anthocyanin rich strains and a lower yield/low growth/low potency? I havent seen this at all, if so id have run back to CMH/HPS. Im left wondering if i persevered further and gave it a fairer shot than you did.

A few questions, when you went from hps to led and had disappointments did you….

Check leaf surface temperatures under hps vs led? What was the difference? At what ambient temps? How close were your fixtures? What was your average ppfd for both and at what distance? If you converted to led and increased ppfd, did you increase overall feed and co2 in accordance with this increase in light?

Its not just the brand of light, you have to give it a real chance. Balance is the key.

 

[Ca++]

If you're talking anthocyanins, they can can express as different colours depending on pH. But my theory on why they express as pinkish-red in cannabis under LED is due to the high amount of red light most LEDs emit, as well as the cyan gap.

Blue light is stronger, but red light has high absorption. Pink-red is also the complimentary pigment of cyan – which LEDs are notorious for lacking – so not all blues are equal, and any pigment change to reflect other colours (red, green, deeper blues and violet) to absorb cyan, which is not in abundance, would reduce light stress/photo-oxidative damage.

I don't want to point the finger at anthocyanins, which are one class of chemicals, out of the three that can bring about some colour. I'm not seeing the deep reds that would make me think that way. I'm seeing reds, that are more shifted to the orange and yellow. Brighter reds. The reds of carotinoids, which are guided by blue light levels.

I only saw this where there is very high light and lower temperatures. It's the carotinoids function to regulate growth speed. Slowing photosynthesis in this case.
Anthocyanins will also slow the plant, but are produced for a wider range of reasons. Things like making it look more attractive after seed production.

This raises fundamental questions, surrounding why it happens, and if it really is anthocyanins. From what I have experienced, I can't say that it is anthocyanins. Though my red, is just one of many.

 

[exoticrobotic]

Im like a battered man at this point. I love icmag so much almost out of nostalgia for what ive learned and shared here over the years. It feels like home. But, its gotten so combative with new people and trolls my patience has diminished.

Cmon man! liiiighten up a bit, it's talk about a light

I loves ya man, not as much as you love Bugbee but...

I DO see more coloration under led

Me too, even when i ran them in summer with 30c temps.

My question is, all things considered in my situation, we have more terps, cannabinoids, yield and overall health even with more coloration. So whats the problem? Where is the link in anthocyanin rich strains and a lower yield/low growth/low potency?

No problem in your environment, you want little to no side branching, tall columnar plants which i believe leds in my cold room promote vs more branchier hid grown plants.

I want side branching for scrog/sog

but If you want further reading the title of the studies i've been reading are

Promoter replacement of ANT1 induces anthocyanin accumulation and triggers the shade avoidance response through developmental, physiological and metabolic reprogramming in tomato​

and

Effect of Red and Blue Light on Anthocyanin Accumulation and Differential Gene Expression in Strawberry​

 

[kro-magnon]

Cmon man! liiiighten up a bit, it's talk about a light

I loves ya man, not as much as you love Bugbee but...



Me too, even when i ran them in summer with 30c temps.



No problem in your environment, you want little to no side branching, tall columnar plants which i believe leds in my cold room promote vs more branchier hid grown plants.

I want side branching for scrog/sog

but If you want further reading the title of the studies i've been reading are

Promoter replacement of ANT1 induces anthocyanin accumulation and triggers the shade avoidance response through developmental, physiological and metabolic reprogramming in tomato​

and

Effect of Red and Blue Light on Anthocyanin Accumulation and Differential Gene Expression in Strawberry​

You can have big bushes under LED even easier than with HPS, the growth under is faster so it's easy to make plants with several tops.

 

[TrifektaSeeds]

LEDs actually do produce a lot of heat, except most of it is conductive/convective thermal transfer as opposed to radiant (IR) transfer. And given the same ambient conditions, the difference in leaf temperatures is minimal, as I showed with the Bugbee study. The difference in leaf temperatures actually narrows as ambient conditions get hotter.

BTW, anyone who knows me knows I don't have my head up Bugbee's arse – LOL! I have been quite critical of some of his methodology, but credit where it's due.

I fully agree that if you need metabolic warmth in your grow room, then use a HID. There are other ways to increase ambient temps inside a grow room or temp, but HIDs make sense if you also need the extra light.

Personally, I live in an area where it doesn't get that cold and my grow is inside the house, so ambient temps in my grow area are manageable and I don't have any real issues with low temps.

As far as anthocyanins increasing leaf temperatures, is it the anthocyanins increasing the temperature, or do increased leaf temperatures produce more anthocyanin? In other words, which one is cause and which one is effect?

On the subject of LED quality, I (honestly) have never heard someone switch from HID to LED (my LEDs, anyway) say they haven't seen an increase in quality.

We have done quite a few trials of LED vs HPS in the past. I have been trying to find photos of LED and HPS in the same room and these are the only ones I could find, as this room was replaced entirely with LEDs back in 2019 because the grower was so impressed with them.

So this is the finished LED grow that you can see on the left-hand side of the next photo
View attachment 18948679

This is the rest of the room. The LED plants were a few weeks behind the HPS plants, so you can refer to the photo above to compare LED and HPS at the same stages of growth. As you can see, the LEDs more than rivalled the HPS with 2/3 the power. These are all the same strain (Paradise Seeds Wappa) being fed from the same nutrient reservoir. The aircon wasn't used. Note the LEDs on the left-hand side – same plants as above.
View attachment 18948678

Here is an earlier LED trial grow in the same room with a different strain (Chimera's Mental Floss).
View attachment 18948680

For every man that says leds are better you'll find one that says the opposite.
I remember back in the day that we used to smoke outdoor and it was cool and nice
Then, the news were flashing one day, watch out ! Hydro ! It will melt your face
Smokers beware haha, and indeed indoor was going strong and was better.
Now, led growers try to justify this tech by saying the end product is better..
But again, you see better, I for one don't see it where I live, not in my grows or others
But I also don't see it in many HIDs ops.
This knowledge of genetics first was known for a long time, lights never and will never be the cause for fire weed, it's only genetics.
Pros and cons of different light techs are strictly for grower use, a killer genetic plant will be fire smoke even under T5s

 

[zachrockbadenof]

, lights never and will never be the cause for fire weed, it's only genetics.

and that is one true statement....

 

[Prawn Connery]

For every man that says leds are better you'll find one that says the opposite.
I remember back in the day that we used to smoke outdoor and it was cool and nice
Then, the news were flashing one day, watch out ! Hydro ! It will melt your face
Smokers beware haha, and indeed indoor was going strong and was better.
Now, led growers try to justify this tech by saying the end product is better..
But again, you see better, I for one don't see it where I live, not in my grows or others
But I also don't see it in many HIDs ops.
This knowledge of genetics first was known for a long time, lights never and will never be the cause for fire weed, it's only genetics.
Pros and cons of different light techs are strictly for grower use, a killer genetic plant will be fire smoke even under T5s

We are all a product of genetics and environment. Environment is what causes genetics to evolve.

And fewer and fewer growers these days are saying HPS is better than LED. But each to his own.

 

[Janborrego]

Show me, show me a pic like i showed u under LED... full trichome heads across the entire flower structure leaves etc... sorry, you wont find one.
LED are great dont get me wrong bro, they are not fitted to flower anything, not stuff that need the highest intensity ever, science says to up the ppdf when your flowering, but science also told u not to go over 1000 ppfd as its not necessary, when you dont go above and beyond (in light intensity) you will get poor resulst, no matter the light source, and LED prove that, just look, leave the science papers in favor of your eyes for a sec.

Full Led only 3 weeks into flower. They are not ready but are stacking up nicely.

 

[Prawn Connery]

Thanks for the reply, I was really happy with the plant in the picture I've shown but I wanted to understand the presence of the anthocyanin with a moderate climate. I tend to defoliate a bit more indeed since I switched to LED because it can be a bit extreme at some point of the flowering and my average humidity can quickly be too high.
I had a Sour Diesel in the same june grow who did not show any sign of purpling so if I understand what you're saying it's a good sign as she is not genetically prone to purpling, I had her more or less dialed as she was all green, I hope I'll ne able to replicate the result in my next run with this genetic.
So far I have been able to get 1G/w with a 465w LED panel, without reflective material on the side, what could I do to improve my yield if you don't mind? (I'll add reflective mylar rapidly)

We do a lot of PAR mapping of lights and having reflective walls makes a big difference to even and intense canopy coverage. Moving from soil to coco (mineral salt, organic or blends) will provide much faster growth. You would probably be shocked by how much – especially once you get into auto-watering systems, but even hand-watering coco can provide quicker results. I don't notice any real difference in taste between soil and organic coco run-to-waste.

 

[Prawn Connery]

I don't want to point the finger at anthocyanins, which are one class of chemicals, out of the three that can bring about some colour. I'm not seeing the deep reds that would make me think that way. I'm seeing reds, that are more shifted to the orange and yellow. Brighter reds. The reds of carotinoids, which are guided by blue light levels.

I only saw this where there is very high light and lower temperatures. It's the carotinoids function to regulate growth speed. Slowing photosynthesis in this case.
Anthocyanins will also slow the plant, but are produced for a wider range of reasons. Things like making it look more attractive after seed production.

This raises fundamental questions, surrounding why it happens, and if it really is anthocyanins. From what I have experienced, I can't say that it is anthocyanins. Though my red, is just one of many.

That's the thing, carotenoid absorption peaks in the cyan range, but most LEDs have very little cyan. 450nm blue pump phosphors are notorious for their cyan gap and Samsung's new 437nm pump Evo is even worse.

Carotenoids do absorb blue and violet, but again, very few LED spectra go into the deep blue, violet and UVA range. I'm not sure I've ever seen a carotenoid stress response in cannabis under LED, but that's just my experience. My LEDs do have UVA, violet and moderate cyan levels.

The caveat is trying to find two spectrum absorption curves that match – there is so much variation that it is hard to know, exactly, where most absorption peaks occur beyond a general range.