Does CRI Make a Big Difference?

Just wondering if there is a big difference in production with a higher CRI Cob... How does it all play out?

90 cri has more red above 700 which promotes both emerson effect and some people say it helps finish faster

Got it.. Thank you

it also may promote stretch in some strains which could be desirable or undesirable in your case

This is really an unknown. By the traditional definition of the PAR spectrum (400-700 nm), most 90 CRI lighting will produce less photosynthetic photon flux per watt than 80 CRI. However, as CobKits stated, it is known that wavelengths over 700 nm have an effect on photosynthesis despite being outside of the traditional PAR range.

The sun is 100 cri, wouldn't the closer to 100 be best?

Corso312 said:

The sun is 100 cri, wouldn't the closer to 100 be best?

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That would be nice, but high CRI LEDs typically have a lower luminous efficiency than their 70-80 counterparts. So you're potentially losing photosynthetic photons for the benefit of better color rendering to the human eye.

I can confirm using higher cri promote stretch notice ! that my plants are very stretchy (haze) it also promoted fox tail.

@Corso have you tasted outdoor weed ? I dont like nature is not perfect nature = survival non stop

I love outties, the only time they don't taste great is if the genetics blow or some milkweed or other plants got stuck in the buds or insects. I'm of the belief that killer outdoor is as good as killer indoor, only the size of the buds give their true identity away.

Ganjineer said:

That would be nice, but high CRI LEDs typically have a lower luminous efficiency than their 70-80 counterparts. So you're potentially losing photosynthetic photons for the benefit of better color rendering to the human eye.

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Thank...that makes sense to use the 80 cri now..always wondered that.

high CRI diodes have their phosphor peak shifted toward the red giving less green but more light at 640 and 680 NM.this produces a lower lumen rating but also a lower LER so may not reflect a reduction in efficiency or radiant power.it would provide more stimulation for chlorophyll A and B.without comparison grows there is no way to know which is best. leds use indigo (450nm) to control stretching so you may need to raise the color temperature with high CRI diodes to get more 450nm light to offset the increase in deep red light

I added 2700k 90cri to my 3500k 80cri lights along with far red after lights out and I am way ahead of schedule. I think this grow will easily finish a week early. Maybe even 10 days.

It would be nice to have the high CRI w/o losing Photons in one cob. If that were the case, I'd say yes all day.

you lose more lumens than photons.
umol/J is not that much different and the fact that theres more red should offset this slight loss

if lumens/PAR were everything wed all be growing with 6500k cobs or 450 nm monos

without a side by side using 70 or 80 cri vs 90 or 95cri we really dont know if the benefit of more colorfull spectrum vs higher lumen makes a difference.is there a side by side like this here? i thought maybe @puffenuff did one?

CobKits said:

you lose more lumens than photons.
umol/J is not that much different and the fact that theres more red should offset this slight loss

if lumens/PAR were everything wed all be growing with 6500k cobs or 450 nm monos

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Any chance you could produce some par measurements, 80 cri vs 90 cri for the same series cob. I don't think I've ever seen that posted here anywhere, All we've got to go on is how many lumens each produce which is meaningless. You've got the li-cor and you stock the chips....so....

I have done a side by side with 4000k 80 vs. 3200k 95+ CRI and the high CRI produced less larf. This was less than a 5% difference in weight and less than 1% difference in THC test. I think the extra stretch helped the high CRI. The lux meter shows that the high CRI is 10% less, but the plants said something else.

My testing started on page 5, in my Sig is the test.

Hybridway said:

It would be nice to have the high CRI w/o losing Photons in one cob. If that were the case, I'd say yes all day.

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if radiant power is the same your photon count would go up with high CRI diodes. 1 watt of deep red light produces more photons than 1 watt of green or orange light and is more useful to plants.with all the unknown variables a comparison grow is the easiest way to determine which is best

nevergoodenuf said:

I have done a side by side with 4000k 80 vs. 3200k 95+ CRI and the high CRI produced less larf. This was less than a 5% difference in weight and less than 1% difference in THC test. I think the extra stretch helped the high CRI. The lux meter shows that the high CRI is 10% less, but the plants said something else.

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What was the total weight for each? Less larf is good but I'm curious what the final weights are