There is a whole lot of info out there going around, about PAR Levels, and Spectrum settings … SOO … I wanted to ask the community … What do you think the best PAR Levels and Spectrum settings are for each stage of growth.
The science is way deep here and 80% of what you try to learn is based off some company marketing so its all misdirection. To actually figure out the par intensities and spectrum combo best for plant would cost millions of dollars and hours of trying each individual wavelength combo throughout a whole plants life cycle.
so each combo for say 60+days straight at least and have live test subjects. Real plants living under this. Different plants different responses.
Were talking 20+ years true
(detailed )research and honestly people are too lazy to do it nowdays.
In the world today People find something that has positive response. Make up the science to back it. Market it and deal with recalls and all later after they cash out.
Now personally i like mixing it all up. Combos. Whether it be t5with staggered bulbs and purple led center or qbs with purple center but i like the mix of whites yellow and the purples everyone hates.
Right now im trying purple cobs on outsides with hps in center but they dont like the hps for some reason. It air cooled so its not heat they just dont like it
I think you want more number based answers but in reality most of those numbers are sales pitch. Who has the real equip to call em on any of it. A par meter is not legitimate equip. They are mostly all trash too unless you spend couple hundred dollars. Then it still isnt disecting anything. Just a little better than the light meter on an iphone. Like i said. Millions of dollars and hours needed in this dept to truly research it all.
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I was able to find this info and it just so happens that these are VERY close to the PAR ranges that I personally use in my grows.
Between 200-400 PPFD: for seedlings, clones, and mother plants.
Between 400-600 PPFD: for early to late stage vegging cycles.
Between 600-900 PPFD: for the flowering, fruiting, or budding stage of plants.
Between 200 PPFD and 400 PPFD, plants growth rate potential crawls around 30 – 55% which is recommended for mother plants or young, weaker plants that need a light that’s not super intense.
If you were to double your PPFD from 400 to 800, the growth rate potential reaches about 85%. You would think that doubling the intensity would push the growth rate
potential pass 100% but the truth is, there’s a loss of power in return the more intense your lights become.
Once you surpass 1000 PPFD and go into Double Ended Grow Light territory, your plants stop becoming light limited and start becoming carb limited. At that level of PPFD, increasing CO2 levels is highly recommended to take advantage of that intense light.
For most growers, CO2 is not necessary. So a common balance between performance and efficiency is in the 600-900 PPFD range.
Keep in mind that this is assuming that you have an ideal spectrum and only represents the potential growth rate on the lighting side and doesn’t factor in other environmental conditions or genetics for optimal growth.
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Also, check out this guide that was produced by Fluence and posted by Muleskinner, over here:
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Lumigrow’s is good too - for the most part all these agree on light levels, temps, humidity, etc…here, I’ve cut out the important part from Lumigrow’s study:
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Does this mean 400umol at 50% efficiency results in the same rate of growth as 800umol at 25% efficiency?
Am I oversimplifying?
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That graph is showing the improvements in efficiency as the CO2 increases.
The way I interpret it is at 400 ppm of CO2 (about the average CO2 outdoors without supplementation), increasing the light intensity from 400umol to 800umol will show a minimum improvement in the carbon fixation by the plant. e.g. the available carbon is limited and adding more light does nothing.
While, if we have 1400ppm CO2, the difference becomes more dramatic between 400 and 800umol. Around 10% improvement since we have more carbon available for the plant to utilize.
So, with our high powered LED fixtures, we may be wasting a good deal of power without CO2 supplementation. Keeping in mind, that the umol/s will decrease as we move away from the lamp (down the stem). So, a bit extra at the top may be perfectly fine.
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Ok and like i said in the beginning. Every single study or piece of data supplied so far is marketing data for a company selling a product.
Try to google and buy a par meter and a meter capable of even reading the spectrums your light puts out. Thatll end the whole debate. You cant buy one cause they dont exist. It requires total lab type large scale research.
“”" Every single study or piece of data supplied so far is marketing data for a company selling a product. “”"
I can tell you for a FACT, that this is FALSE KNOWLEDGE, that you are spouting.
I have been growing cannabis for 25 years.
I PERSONALLY participate in the STUDIES of CANNABIS as well as the TESTING of LEDs, and my ONLY GOAL, is to INLIGHTEN MYSELF and OTHERS.
I am not doing what I do for “MARKETING DATA” … I SELL NOTHING.
I am doing what I do for - The Education of Cultivation and the Cultivation of Education.
And about this …
“”" Try to google and buy a par meter and a meter capable of even reading the spectrums your light puts out. Thatll end the whole debate. You cant buy one cause they dont exist. It requires total lab type large scale research. “”"
The one I use …
Not only do they exist, but also, not even the most expensive “INDUSTRY STANDARD PAR METERS” are anything close to as expensive as you are making them out to be.(price is stated in linked video @ aprox 2:00)
Please watch this video.
- The only way to expand your mind, is to have an open mind.
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Watched it. It proved exactly what im saying.
Not that you are trying to sell something. Not at all what im saying. Im saying all of the tools dont actually answer the questions. And sold seperately there is another piece to get you closer. But it never gets to a true answer. True flat out intensity numbers per wavelength of light
Breaking down exactly how intense each color is in the blend. Without that you are not figuring out anything. To have that you need a lab and at least hundreds of thousands of dollars tied up in multiple pieces of equipment and then put a marijuana plant under each combo for 60days to see its responses to said intensties and wavelengths. Like i said its wayyy deeper than im willing to go and lot deeper than just buying some crap par meter and holding it under a light. The cheap meter was $200next up was $600. The equip you need is about $10000
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so everybody shotguns it and saturates as much as they can. Not energy efficient but then neither is bitcoin.
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Yes, I’m guessing pretty much the case.
I’d assume a good portion of the set-ups are probably a bit under-powered anyhow. It’s surprising how much power it takes to get even coverage at the suggested intensities. All hale the sun…
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Not sure about the accuracy of the CO2 graph, I’ve seen the same chart from other sources with different conclusions. If you use that graph then there’s no reason to go above 400 umol/sqm during flowering without extra CO2. I’ve seen 600 in other graphs, that matches my experience better.
These figures from the LED companies do seem to suggest there’s not much increase in yield above 600-700 umol/sqm without CO2. That’s an eye-opener, for years the lighting companies said it makes sense to go up to 1200 or 1400. Maybe it’s partly the difference between LED and HID, you don’t need as much.
here’s the other graph from my files - I have no idea where it came from. I assume the numbers are for normal levels of CO2.
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Don’t know, haven’t studied their graphs in detail.
Here is a research paper on the topic: 12298_2008_Article_27 (1).pdf (545.9 KB)
This is also some relation to the DLI that probably comes into play. Ends-up being a 3d set of variables.
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interesting, here is their version of it - this curve matches my chart w/ the green bars - this would imply that going to 1000 umol/sqm makes sense
and for greenhouse managers this is important - 600 is the max if you want to save water
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For those who don’t know, you can use your mobile phone to measure lux using one of those light meter / lux meter apps. Then you can convert those values to find PPFD. I’m using Quantum Board QB288 v2 and use Horticulture Light Group (HLG) online calculator to convert from lux to PPFD. Granted that this is not super accurate, but it will do for some of us hobby growers.
Lux to PPFD Calculator for Quantum Board here:
And as mentioned in this thread, the optimal PPFD for different stages of grow is on point with what I’ve researched and recommeded by HLG at that URL above.
However, I have recently noticed that if use PPFD of around 900 PPFD which is around 6000 Lux during flowering, the top of my plants started yellowing. I’ve also burnt a couple of plants by strictly following the recommended PPFD values, so I guess, use these recommended value with a grain of salt. BTW, in order to get these 900 PPFD, I had to lower my QB288 down to about 12" above canopy and that might be too close.
Anyway, so I am backing off the light to about 18" above canopy and waiting to see if I’m still burning my plants.
I’m curious if anyone here using Quantum Board and have found optimal PPFD, Lux, and/or distance to canopy.
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Ambient co2 levels will still give you a better yield at 600umol than 400umol, just inefficiently. I’ve been told that co2 isn’t worth it unless you’re pushing 1000umol but this one makes me question that. But let’s take ppm completely out of the equation for a second.
If your plants are operating at 50% efficiency, and they’re receiving 400umol, they’re only able to use 200umol.
so will that equate to the same speed of growth as 800umol at 25% efficiency, or am I oversimplifying? i.e. at higher light levels the plants may produce more secondary compounds that don’t directly translate to a larger plant.
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This is a good read:
http://www.plantphysiol.org/content/125/1/29
What happens when a plant receives more light than it can utilize, etc.
…tapping this in from my phone, sorry bout that…
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Youre right. You found all of it right there.
Can you tell me what your own light puts out now that you got all that money in it?
How much blue to red yellow white. Nms however you want to scientifically break it down. Spectrum. Can you tell the intensity of each spectrum? No. That must be done through a plants whole life cycle to say one is better than the next. They must both be run full life cycle and compared ,graphed. Now how many spectrums?
Oh now What was your light doing again? Exactly Google can tell you. They cant lie on the internet.
Im going to roll in some donkey colas while you chase a dream.