Red light best for budding?

Respect to the R Spec
5ft x 5ft, 650 watts

cdgmoney250 said:

I have reservations about spectrums with these massive red spikes relative to the other colors. I’m currently using the R4 spectrum from Fluence and was able to run long and short flowering plants at 1500-1700 ppfd (Edit: without CO2 supplement) without stress or issue and the yield and quality are some of the best I’ve had (living soil/water only). I feel if the spectrum is imbalanced and weighted too much towards the red end, plants tend to exhibit photooxidation and photoinhibition at lower ppfds than a more balanced spectrum (relative intensity of the different spectra) still including the same nanometers. While I agree that the addition of far red and UVA is no doubt beneficial overall, if there is too much of either relative to the rest of the spectrum, potential photosynthetic efficacy is diminished. With the red heavy spectrums, photosystems I & II get overworked by the quantity of red photons, and therefore can’t do the repair work they are supposed to as efficiently under higher flux conditions. This is probably why you are seeing oxidative stress above 1200 ppfd. Just my personal perspective based on lots of reading and trials under different spectrums. Not shilling for Fluence, but I picked up the Spydr series mainly because of the spectrum, secondly because of the output, and certainly not because of the price. Compared to modern sun-like LED chips, their spectrum isn’t even that broad, but it is fairly balanced compared to most commercial fixtures. My 2 cents

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Again, apologies for being late to the party, but I'm limited for posting time these days. However, these threads do at least give me an excuse to research!

So I guess the first question is, if you are growing cannabis, what light level do you use to flower without supplementary CO2 and how do you measure it? You've run both short and long-day plants between 1500-1700 PPFD, so it would be good know what variety of plants you've grown, and – if cannabis – which cultivars.

The second question is, if you are growing under 1700 umol/j without supplementary CO2, are you getting twice the yield compared to, say 850 umol/j? The point being, at what level are you seeing diminishing returns? This is going to segue a little bit with what I'm about to write, so please don't think I'm putting you on the spot! I'm genuinely curious about your results.

That said, I don't disagree with the premise of over-saturaing chloroplasts with narrow-band spectra, but there are a few things to consider.

Chloroplasts are dynamic – they actually move around inside plant cells and can orientate themselves to capture more light or to avoid it if intensity is high. This is a facinating short read: https://books.google.com.au/books?id=aQR__H2XBnUC&pg=PA236&lpg=PA236#v=onepage&q&f=false

But for the TLDR cowd, here is a diagram to explain what I mean. The square box is the plant cell, and the grey dots are chloroplasts. In strong light, the chloroplasts turn sideways and align themselve around the outer edges of the cell to allow light to pass through without being absorbed. In low light, they turn horizontal and align themselves in layers in such a way that any light that passes through the first layer is captured by the second layer:


The point of mentioning this is that, although yields may increase with light intensity up to a certain level, photosynthetic efficiency also starts to drop off at some point.

Chloroplasts are also dynamic in that they can alter the production of each pigment to take advantage of certain spectra or to protect themselves from intense narrow band photons. We've all seen this: healthy leaves exhibiting a dark dreen/blue hue in the presence of bluer light (Metal Halide or high CCT LED) and a lighter green hue in the presence of red/yellow light (HPS or low CCT LED).

And you are entirely correct about a balanced spectrum being the best. The only point of difference is "what is a balanced spectrum"?

Chloroplasts are dynamic because sunlight is dynamic. It may be around 5700K at noon, but it varies between that and ~2000K at the beginning and end of each day. On average, sunlight is probably around 3500-4000K throughout any given day. This will change with different seasons, latitudes, altitudes, weather and atmospheric events. You get the idea.

Chloroplasts change because sunlight changes.

So which is the best sunlight spectrum? Is it Spring/Autumn when the days are shorter and redder? Is it in the middle of summer at noon when the UV index is highest? Or do we need different spectra at different stages of growth?

One thing that is missing from a lot of LED grow lights is Far Red – which is crazy IMO. Sunlight from 400-800nm has 25% Far Red light! Many LEDs have almost none and most have very little, with red: far red ratios of 12:1 or higher. Our lights have less than 4:1 (11% Far Red).

Disclaimer time: if you don't already know, I am affiliated with Grow Lights Australia and do a lot of their testing.

Far Red increases photosynthetic efficiency in many ways, one of which is by quenching chloroplasts to enable them to absorb more light without oxidation – especially in relation to red photons.



At the other end of the spectrum, UVA, Violet and Blue counter some of the underdsirable cell-expansion properties of additional Far Red such as excessive stretch, whilst still encouraging larger leaf area. Which is why plants don't stretch under full sun even though it is 25% Far Red.

All of this, however, is a bit moot in the face of grow stats. The best spectrum is the one that gives the best metrics. It is here that opinions may vary. You can tweak your spectra to produce more dry yield or higher cannabinoid and/or terpene content, because it appears there is always a trade-off between these two photomorphogenic responses depending on which end of the spectrum you favour – although I believe the secret is to balance both ends by including UVA and Far Red and also trying to increase Cyan (which is almost impossible to do efficiently with current LED technology).

And yes, may be right that the best spectrum is the one that allows you to push the most photons with a linear – or even absolute – increase in yield until you get to the point of diminishing returns.

What I can say is we've tested R4 type spectra against our own and our yeilds have been better – at least within the parameters we set, which was around 800 PPFD at the canopy when scrogged. Obviously it makes a difference if most of your canopy is getter 800PPFD compared to Christmas tree style growing where the top cola gets 1200 PPFD but most of the lower plant only gets 400-600 PPFD.

Here's the test: https://www.rollitup.org/t/growdown-mars-hydro-vs-grow-lights-australia.1076599/

This one was only a difference of about 7% in our favour, but we've run these before with similar and better results conducted by growers with a bit more experience than the guy who grew these out ^.

Here are the spectra used.

loco41 said:

I was able to finally set up my small 2x2.5ft tent and hang up my GLA original highlights boards once again. Not the most experienced grower, but these lights seemed to serve me better than the 3500 80 cri cobs I had used previously. Not quite as "advanced" as their newer boards but I still think they offer a bit fuller spectrum than the standard options.

Here's the spectrum just to add to the mix we have going in this thread already..

View attachment 5324118

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That was the very first LED light I designed in 2018 using a combination of Nichia Optisolis for the Far Red and Seoul Semi for the UVA. It has 5% Far Red and 0.4% UVA. There are still guys growing phenomenal weed with these LED panels. 2.5 umol/j as well.

This was the next one I designed with LED Teknik – the original High Light 420 board (with 420x LEDs). It was 3.01 umol/j – which was really hard to achieve with the added UVA and Far Red, because the diodes are not very efficient

cdgmoney250 said:

I’m currently using the R4 spectrum from Fluence and was able to run long and short flowering plants at 1500-1700 ppfd (Edit: without CO2 supplement)

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So I got pretty baked last night and went off on a bit of a tanget . . . lost my train of thought so I didn't end up writing what I had originally planned, lol!

There was a fairly comprehensive study into the relationship between light intensity and yield conducted a few years ago titled "The Profitablity of Growing Cannabis Under High Intensity Light". A synopsis of the study is here: https://agnetix.com/app/uploads/2019/05/The-Profitablity-of-Growing-Cannabis-Under-High-Intensity-LightCR-Highlights.pdf

That study determined a linear increase in yield up to 1500 PPFD and involved hundreds of plants and six different LED light fixtures and a DE HPS. The important thing to note is this study used 1400 PPM CO2, so while I said earlier I was not trying to put you on the spot, in a way I am doing just that by asking how you are able to grow under 1500-1700 PPFD without CO2.

Of course, there are different ways of measuring things. The above study was up to an average 1500 PPFD across the entire canopy. Depending on the light, spot readings can easily be around 1500 PPFD with an average of 1000 PPFD or less. My lights have a pretty good spread, but here's a PAR map of one showing a peak of 1473 PPFD with an a average 1232 PPFD over a 4x4 area. There is also significant intensity drop-off as you measure deeper into the canopy, but I'm going to assume you are talking about maximim PPFD at the top of the canppy not exhibity any signs of photo-oxidative stress.

Ignore the "lx", these readings are all in PAR. 1473 PPFD max, 919 PPD min, 1232 PPFD av


As for the study itself, there appear to be a few issues with it. They got 0.77gpw on average under LED and 0.35gpw under HPS – which are terrible figures in anyone's language and make me wonder how such a commercial operation can have such poor yield figures for a 60-day strain that is normally a very good yielder (Green Crack, which is a Skunk#1 x Afghan variety).

I regularly pulled up to 1.3gpw from my vertical 1200W HPS set-up in a 4'x4' with 10-11 week strains. I better that under LED, averaging over 1.5gpw. Here's 2lb from a 4x4 under about 600W of LED pulled the other week. Some signs of light stress if you look closely (curled leaf margins), as I let some of the plants grow into the lights a bit – although I don't mind sacrificing a small amount of bleaching if it means better canopy penetration and overall better results.

And I don't use CO2, so if that study is only getting 0.35-0.77gpw with 1400PPM CO2 and 1500 PPFD, then they obviously need a new "master grower" lol! I like an average 900 PPFD in my grows, but it depends on the strain. Sativas can go up to 1000 and some indicas (especially the new "cookies" type genetics) prefer 800. This doesn't include an extra 100 PPFD of Far Red that is not counted by traditional PAR meters.

And I am talking "average" PPFD across the entire canopy, which means it will be as high as 1200-1300 PPFD in spots, but that's really as high as I can go and will often exhibit undesirable growth, such as elongated internodes, smaller, airier flowers, and obviously some bleaching (oxidation).




Lots of red and far red light in there. 1lb plant from the same grow (dried, trimmed)


This is all just a long was of saying, I'm not sure how anyone grows under 1700 PPFD without CO2, but I'm damned curious to see the results!

Prawn Connery said:

So I guess the first question is, if you are growing cannabis, what light level do you use to flower without supplementary CO2 and how do you measure it? You've run both short and long-day plants between 1500-1700 PPFD, so it would be good know what variety of plants you've grown, and – if cannabis – which cultivars.

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So to preface all of your questions, I’d like to give a little context as to the growing conditions I went through, which was by happenstance, not by design. I run a sealed closed loop 4’ x 8’ tent with A/C, Dehu, and CO2 tank injection and 10 mini fans. I measure light levels with a Apogee Quantum Meter MQ-610 which measures 400nm - 750nm.





1500ppfd was about 5-6” down from the light.

(the plants in these photos are moms getting nursed back to health with the light turned down to 20%)


Air Conditioner failed 2-1/2 weeks into veg, so I had to open up my tent and use the ambient central air cooling from my house to maintain temperature. Because my tent was no longer sealed, I turned off my CO2 because otherwise it would have just been a waste of air and money. This is what led to the growing conditions I experienced.

Now to answer to answer your questions. It’s a cannabis tent, and that’s primarily what I grow in it. I grew short and long flowering plants, meaning some plants were done at day 60 and some weren’t quite finished by day 90. I grew out 3 different strains from seed, and had many varying phenotypes. Some of the greatest differences between plants were different sisters of same same strain. The strains were [Unicorn Poop x Meatbreath] by Thug Pug genetics, Oppenheimer OG F2 by Nature Farm Genetics, and Non-GMO by Mountain Organics Seeds.

Prawn Connery said:

The second question is, if you are growing under 1700 umol/j without supplementary CO2, are you getting twice the yield compared to, say 850 umol/j? The point being, at what level are you seeing diminishing returns? This is going to segue a little bit with what I'm about to write, so please don't think I'm putting you on the spot! I'm genuinely curious about your results.

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I would like to clarify that 1500-1700 ppfd wasn’t the overall average, just that the branches that did experience these light ranges were the largest/frostiest/most developed buds in the tent. Many plants kept trying to grow into or past the light and I had to keep pulling them down to keep the tops from burning (actual burning from touching the LEDs).

Because I grew different plants from seed, I can’t speak to the differences in yields for the same plant under different light intensity as I don’t have the data for that. With that said, it’s the most light I’ve grown under, and the yield was terrific. With THAT being said, some of the cultivars yielded little more than 1/4”lb, and 3 separate plants yielded over a lb each. All literally growing side by side in the same 3’x 6’ bed of soil. Total yield metrics don’t mean much to me, because there are so many factors that affect yield, cultivar being a big one. The best way to test plants (and growers) is to run the same cut multiple times under varying conditions, and that’s how you can get a good report card going.

Prawn Connery said:

And you are entirely correct about a balanced spectrum being the best. The only point of difference is "what is a balanced spectrum"?

Chloroplasts are dynamic because sunlight is dynamic. It may be around 5700K at noon, but it varies between that and ~2000K at the beginning and end of each day. On average, sunlight is probably around 3500-4000K throughout any given day. This will change with different seasons, latitudes, altitudes, weather and atmospheric events. You get the idea.

Chloroplasts change because sunlight changes.

So which is the best sunlight spectrum? Is it Spring/Autumn when the days are shorter and redder? Is it in the middle of summer at noon when the UV index is highest? Or do we need different spectra at different stages of growth?

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I would say sunlight (as seen on earth), is about as balanced a spectrum one could find. When I say balance I mean a minimum difference of radiant intensity from lowest to highest across the photosynthetically active range of nanometers.

Sunlight is dynamic, and changes in spectrum and intensity throughout the day, and likewise from season to season. This is how plants evolved so I would assume this would give us the best plant response if we’re to try and recreate optimal growing conditions indoors.

Prawn Connery said:

That study determined a linear increase in yield up to 1500 PPFD and involved hundreds of plants and six different LED light fixtures and a DE HPS. The important thing to note is this study used 1400 PPM CO2, so while I said earlier I was not trying to put you on the spot, in a way I am doing just that by asking how you are able to grow under 1500-1700 PPFD without CO2.

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I don’t know man, grow environments are pretty dynamic so I just try to keep all the parameters in check. Also, like I said in my previous post, the average intensity my buds saw was not 1500-1700ppfd. Probably more like 1100-1350ppfd.


Plants outside grow under 2300 ppfd with about 400 ppm of CO2. How do they do that according to the studies you linked?

Humidity around 55%, leaf temps around 82-85 degrees F. I use soil moisture meters to keep the soil moisture content dialed. I start shortening the days and lowering temps around week 5 to reduce DLI, but I don’t turn the intensity down until the last week or two down to 80%. The last week the lights are on between 9-10 hours at 80% max intensity finishing at 50% RH and 76 degree leaf temps.

My soil is also pretty dialed in nutrition-wise, which can play a huge role in how well plants photosynthesize.



this mix had just a wee too much K and N and the room got hot at week 7 because my house ac failed in the middle of summer and room got up to 99 degrees.


This ^^^ was before the room was done stretching and started to swell. They closed the gap to the lights by almost 50% from this photo and I had to snap quite a few necks.








This plant ^^^ exhibited some heat stress from when my AC went out (the second time)




Sorry for the photo dump, but if I’m gonna get called out, I gotta put up.

Thanks for taking the time to post all that up mate. Initially you mentioned "long and short flowering plants" and I read that as "long day/short day", so my bad. Obviously cannabis is a short day species.

cdgmoney250 said:

I don’t know man, grow environments are pretty dynamic so I just try to keep all the parameters in check. Also, like I said in my previous post, the average intensity my buds saw was not 1500-1700ppfd. Probably more like 1100-1350ppfd.

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That probably makes a bit more sense to me when we talk about average PPFD, and of course those high figures around 1700-1800 PPFD are directly under each light bar at 4" so that puts things into perspective.

It's a great grow – nothing wrong with the quality by the looks of it – but there are some signs of stress if you look, including fox-tailing, twisted leaves and a small amount of bleaching.

Not criticising, just pointing out that IMO you're running on the ragged edge. But again, nothing wrong with that if you are getting the results you want, especially into the deeper canopy that doesn't see the same PPFD extremes.

The main reason for raising metrics is to give us all an idea of whether you would get even better results if you dialled it down a notch. Or if, in fact, you have achieved a happy medium where the top buds get blasted while the lower canopy is bathing in a more manageable light intensity.

It's hard to know without comparing apples to apples.

But I'm also the kind guy who says if it works for you then stick at it. You can't argue with results.

However, all said and done, there is a big difference between scrogging at high PPFD levels and free-stand growing where only the tops are getting those levels. Here's an example:

Some of these plants got very close to the light and were getting 1500+ PPFD at those points . . . but overall, I had to use supplementary side-lighting to get more light into the lower canopy.







But I wouldn't be aiming for those same high PPFD levels with a scrog, as most of the canopy is evenly exposed:


The point being "average light intensity" is just that. Light drops off very quickly once you get further away from the fixture – especially with bar lights that spread their light over a very wide angle – so I still maintain the average grower is going to see some issues with an average intensity of 1200+ PPFD over the entire grow.

Here is one of my earlier LED grows from a few years back when I subbornly refused to turn my lights down because at the time I couldn't believe I could replace a 600W HPS with less than 400W of LED – even though the PPFD readings were 1300+ across the canopy.


I learned my lesson, and here is the spectrum that did it: it is very balanced – certainly less peaky around 660nm than your Fluence.

cdgmoney250 said:

Plants outside grow under 2300 ppfd with about 400 ppm of CO2. How do they do that according to the studies you linked?

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This one is pretty simple to explain: DLI

Daily Light Integral is the total amount of light the plant sees each day. As you've already mentioned, sunlight is dynamic – so those 2000+ PPFD levels are only seen in the middle of the day, on a clear day at certain times of year in certain locations. I live in Australia – one of the sunniest places on earth – and I only see those levels outdoors in late spring/summer/early autumn around mid-day on a clear day. The rest of the time, PPFD levels are lower.

This is what DLI looks like throughout the year. Don't ask where this is, as I just ripped it off the net. But it shows you how DLI changes from season to season. Obviously it is somewhere in the nothern hemisphere.





OK, here's DLI in Sydney, Australia, over an 18-month period. Just look at the differences in readings even at the same time of year! Each dot is a different day:


And of course, here is how light intensity changes throughout the day on any given day. Don't look at the PPFD figures, just look at the hourly trend:


The main difference between sunlight and articificial light is that, due to the inverse square law sunlight bathes the entire plant – from top to bottom – in the same intensity, whereas artificial lights lose intensity very quickly from top to bottom.

Lots of long posts and lots of good information, I'm sure. Here's my take:

When I started growing back in the 1970's, I used regular fluorescent shop lights....mainly because it wasn't "suspicious" to own or buy them. The color they put out, as you know, is very blue-heavy. And they are very weak and inefficient (by today's standards). The plants, themselves, were not hybrid plants, at that time. They were bag seeds mostly from landrace sativa plants from Mexico. They grew very small under the fluorescents. I'm pretty sure that, in their natural lighting environment, the plants grew much taller.

Now that everyone is growing hybrid plants, I really couldn't say what the growth characteristics of a given plant will be until they are grown a few times. There are just too many variables with all the selective breeding. Even the most efficient lights and most ideal spectrum can't make a wispy SE Asian sativa, into a compact, dense flower.

I like Bruce Bugby and all, but which type(s) of cannabis varieties are being tested to achieve those results? -same question to all the cannabis lighting experts, too.

If all other environmental factors are the same, I think a good LED fixture that puts out more light than you need, in conjunction with a dimmer that will allow you to keep from burning the plants, will give a basic-grower good results....IF the plant's genetics are there!

For me, each grow is slightly different, since I rarely run the same strains twice. So, one type of light spectrums and intensities might work better for some strains and not as well for others.

It's just a matter of how fine does one want to split hairs about this stuff? Light manufacturers will argue all day long over 2 micro moles per joule or 2.5 micro moles per joule, but, in the end it's not really going to make ant practical difference because there's such a vast amount of hybrid strains -all of which have been selectively bred for specific/unique traits. Is there a generic cannabis plant that can successfully represent ALL those traits in order to help lighting experts quantify/confirm their test results?

tstick said:

It's just a matter of how fine does one want to split hairs about this stuff? Light manufacturers will argue all day long over 2 micro moles per joule or 2.5 micro moles per joule, but, in the end it's not really going to make ant practical difference because there's such a vast amount of hybrid strains -all of which have been selectively bred for specific/unique traits. Is there a generic cannabis plant that can successfully represent ALL those traits in order to help lighting experts quantify/confirm their test results?

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There is certainly truth to this and we have said all along that different strains have different lighting requirements. I've seen it myself when growing different strains under the same lights. But that has more to do with lighting intensities as opposed to spectrum. Plants have a degree of plasticity and can produce more or less of certain types of pigments to adapt to the light they get – in the same way they have ways to adapt to different light intensities.

However, one thing I have noticed is that a lot of modern strains these days have very similar genetic backgrounds: they have all come from the same OG > Cookies clones and seem to be variations of the same theme. So breeders do seem to be bottle-necking genetics at the moment.

I'm lucky to have a lot of older genetics I've collected over the years, so it's always interesting to compare. Even though I haven't seen a huge difference, there are some. For example, a lot of OG type strains tend to stretch like a sativa dom with a similar bud and branch structure, but have more compact buds and larger calyxes like an indica but without the heavy couch-lock.

I'm growing old-vs-new at the moment. I have a single Sweetopia (Thin Mint Cookies x Citral) in the middle of 4x my own cross which I made over a decade ago from a very old clone that used to do the rounds in my part of Australia. It was a very heavy old super skunk variety – no-one really knew what it's genetic make-up was, it had been around so long – and I crossed it with the strongest varieties I had in my possession at the time, namely Sensi Star x Sweet Tooth #3. So the cross is a poly-hybrid of three of the strongest indicas that were around at the time and it is starting to show in the variation now that they are starting to flower. They were quite uniform in veg. One thing I do know is that my cross should smash the Cookies cross for yield, which is really quite poor even though it has nice terps. But the clone I used for my own cross had a very strong terpene profile too, so I am very interested to see how they compare . . .


I still think the efficiency debate is valid because better efficiency and fewer watts helps with heat management.

I'd say the best spectrum for flowering depends on who is growing the bud. 4000k with 600nm reds will be more than enough for the vast majority of growers. You would assume around 5% far red from that spectrum, and with newer horticulture whites you are getting the near-uv effects. Besides substituting some green for red, I'd say any added spectrums are probably better done in 'light-treatments' when the plant has finished stretching, done with separate dimmable light bars for UV/Far red. Again, it comes back to the grower... although light is the most important nutrient in growing, there are other factors like temperature, humidity/vpd, airflow, and NPK ratios and concentrations. Light alone, let alone spectrum, is not going to give us some type of giga-buds. And last but not least genetics play a big role in what is best, and even more importantly knowledge about the genetics in relation to all the other factors mentioned here. Edit: 660nm reds, and of course CO2

Man, we used to just throw seeds out into a plowed field near a drainage ditch and then come back at at the end of the summer to see if anything grew...and something always did! Times have changed and now we can get really, really specific about all these technical details....but, so far, I haven't smelled or smoked any weed that was as good as the Thai weed I got in the 70's. I haven't smelled or smoked anything that comes near the Gold Columbian I used to get....or the Bluberry Skunk...and so on. So, even with all the technical advancements that have been made in lighting and all the other stuff, the weed still doesn't smell as strong or taste as good as it did decades ago when there was very little "advanced" equipment available to grow it. It was just better tasting genetics that were all a lot closer to what we now call "landrace" strains. If there was a way to get those old genes back into the pool and then apply all the new technology to growing them, I think it would be fantastic. But, all of it is just legendary, now. People say they have things....hrrrrmph. Anyway, red light, blue light...whatever light...there's no way to consolidate a standard formula for the optimum light to grow cannabis, with so much diversity in the gene pool now. It's like you have to take each plant on an individual basis and then try to dial in a formula for every little thing that a particular strain likes best. And if you grow several varieties, then you're just going to have to try and find a happy medium among them all.

tstick said:

Man, we used to just throw seeds out into a plowed field near a drainage ditch and then come back at at the end of the summer to see if anything grew...and something always did! Times have changed and now we can get really, really specific about all these technical details....but, so far, I haven't smelled or smoked any weed that was as good as the Thai weed I got in the 70's. I haven't smelled or smoked anything that comes near the Gold Columbian I used to get....or the Bluberry Skunk...and so on. So, even with all the technical advancements that have been made in lighting and all the other stuff, the weed still doesn't smell as strong or taste as good as it did decades ago when there was very little "advanced" equipment available to grow it. It was just better tasting genetics that were all a lot closer to what we now call "landrace" strains. If there was a way to get those old genes back into the pool and then apply all the new technology to growing them, I think it would be fantastic. But, all of it is just legendary, now. People say they have things....hrrrrmph. Anyway, red light, blue light...whatever light...there's no way to consolidate a standard formula for the optimum light to grow cannabis, with so much diversity in the gene pool now. It's like you have to take each plant on an individual basis and then try to dial in a formula for every little thing that a particular strain likes best. And if you grow several varieties, then you're just going to have to try and find a happy medium among them all.

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I think part of this yonderyears smelled better is simply down to weed grown in direct sunlight simply gives a better smelling/terpy product than indoor, even if some parts of "quality" is lacking in outdoor. We recently had one of our best harvests ever, everything on point. But my 3x 1 euro auto-haze growing with little help and care on the terrace, with massive misshandling and neglect and drought conditions still smells like 10 times better than our "prime" weed.
We tend to mainly smoke indoor weed know, with a process of breeding that favored non stinky plants for a lot of generations. Of course its not the same as before.

I used to run those 4 or 5 years ago. I would leave the blue on for the first 3 weeks during the stretch to keep them tightly stacked, then switch it off.

After you paw through all the graphs and pie charts, decide if you want to turn it off after. I noticed a lot of foxtailing on sensitive strains

Rocket Soul said:

I think part of this yonderyears smelled better is simply down to weed grown in direct sunlight simply gives a better smelling/terpy product than indoor, even if some parts of "quality" is lacking in outdoor. We recently had one of our best harvests ever, everything on point. But my 3x 1 euro auto-haze growing with little help and care on the terrace, with massive misshandling and neglect and drought conditions still smells like 10 times better than our "prime" weed.
We tend to mainly smoke indoor weed know, with a process of breeding that favored non stinky plants for a lot of generations. Of course its not the same as before.

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Sunlight and the fact that most of the plants were specific to a specific region...soil, light, humidity....And each of those strains was well-adapted to grow that way after years of growing in the same places and became unique. Yeah and since they were plants that grew outdoors, the plants had adapted to really send out the smell -so that something out there could find the plants and "interact" with them.
I know that growers back then bred out a lot of the smelly strains just to keep from getting caught and going to prison! But, I can't imagine that anyone is still doing that now that everything has relaxed. I would have thought that someone would have been able to breed back the goods and corner the market with the real deal by now....but nope...not yet. But I'll say that I've seen a lot of people advertising those old strain names. I've been looking through as much of it as I can get my hands on. So far nothing even enters the ballpark! It's all lies! I dunno, man....I hope someone figures it out!

tstick said:

Sunlight and the fact that most of the plants were specific to a specific region...soil, light, humidity....And each of those strains was well-adapted to grow that way after years of growing in the same places and became unique. Yeah and since they were plants that grew outdoors, the plants had adapted to really send out the smell -so that something out there could find the plants and "interact" with them.
I know that growers back then bred out a lot of the smelly strains just to keep from getting caught and going to prison! But, I can't imagine that anyone is still doing that now that everything has relaxed. I would have thought that someone would have been able to breed back the goods and corner the market with the real deal by now....but nope...not yet. But I'll say that I've seen a lot of people advertising those old strain names. I've been looking through as much of it as I can get my hands on. So far nothing even enters the ballpark! It's all lies! I dunno, man....I hope someone figures it out!

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I remember getting some insanely good weed from malaysia when I lived in singapore as a teenager. I've never gotten close to anything that even remotely resembles it. It was damn near psychadelic. I guess it's like most stuff that gets produced on scale, it becomes bland and stripped of its vitality. You can still find some of the good stuff around, but you'll actually have to do some travelling to find it. Here's a good resource if you are serious: https://www.youtube.com/@pakandafghancannabisseeds4896

Fangthane said:

Possibly just bro-science that I never bothered to fully explore, but I was under the impression blue lighting in flower supposedly increased cannabinoids. Not sure how the total power in their light is divided up between white, red and blue, but presumably there would also be measurable yield penalty from losing a percentage of available wattage by switching off the blue.

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Blue photons don't increase cannabinoids.
According to Dr Bruce bugbee
UVA does not increase cannabinoids either.

Topshelfruns said:

Blue photons don't increase cannabinoids.
According to Dr Bruce bugbee
UVA does not increase cannabinoids either.

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Yes they do. Bugbee doesn't grow cannabis, he grows hemp. Utah University is not allowed to grow high-THC cannabis, so they grow hemp and CBD-rich strains instead.

Any industrial hemp farmer can tell you that the higher the UV index outdoors, the higher the THC concentration. Outdoor help farmers in Australia have had this problem for years, as they would import hemp seed stock from China, where it tests <0.5% THC, but when grown outdoors under a higher UV index, those levels would spike to >1%

That is why most industrial hemp legislation across Australia stipulates that only 0.5% tested hemp seed can be sown, but THC levels from subsequent crops are allowed to be as high as 1% to account for environmental factors such as UV radiation in different areas.

Indoor cannabis growers have also known for years that plants grown under MH have higher THC levels than those under HPS, but yields suffer. HPS has very little blue light and almost no UV. MH has substantially more of both.

The Magagnini et al research paper was one of the few that actually used high THC varieties to determine if blue/violet/UV increased cannbinoids, and it did. And they conducted two trials, which both aligned. Other trials have either used low THC-plants (hemp) or have had some serious concerns about their mothods. The Llewellyn trial used high THC-plants but did one trial and their methodolgy was suspect. They had a lot of botritis in their grow and, in fact, some parts of that trial showed visible increases in trichomes with the addition of UVB and UVA, but they also didn't run UV throughout the trial – only in the last 20 days, which was beyond the peak expression of cannabinoids in most 8-week varieties.

I could go on but, we've done our own trials and found UVA certainly makes a difference to THC concentrations. Three trials all showed the same results.

EDIT: Here is the Magagnini et al paper: https://karger.com/mca/article/1/1/19/189037/The-Effect-of-Light-Spectrum-on-the-Morphology-and

Of note is that the trials were conducted using Valoya lights. Valoya claims to have conducted over 500 different cannabis trials and is one of the leading horticultural LED light producers in terms of spectrum and spectral research.

Here is the Llewllyn paper: https://pubmed.ncbi.nlm.nih.gov/36237501/

Here is the Bugbee paper: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7987162/#pone.0248988.ref006\

None of the Bugbee plants had any violet or UV in them. There was almost no radiation below 430nm. All the Bugbee study proved is that 450nm LEDs don't appear to have much impact on high-CBD plants – because no high-THC plants were used in the trial.



In fact, the higher the THC percentage of the plants used, the more of an effect blue light had on THC levels. Trial 3 actually showed an INCREASE in THC levels in plants that were higher THC to begin with as blue photons increased. Bugbee says it is statistically irrelevent. I say other scientific experiments show otherwise.

I further argue the Bugbee paper is inconclusive in stating that blue photons have no impact on THC levels when one of the trials showed exactly that.

I'm also not going to cast aspersions, but I will say this:

Bugbee never promoted the benefits of Far Red light . . . until his company, Apogee, started making an "ePAR" meter that measured Far Red up to 750nm. For the longest time, he either ignored the evidence or said it was inconclusive. Until his company started promoting it.

Apogee still doesn't make a consumer PAR meter than includes UVA. The ePAR meter includes some of the UVA around (just below) 400nm and lo and behold – what does Bugebee say about this range (just below 400nm)? Why, it is "beneficial". Doesn't really explain "how" it is beneficial, but still – now you have an ePAR meter that can measure all the "beneficial" light!


Bubgee's research has its place. But he is far from an expert on high THC cannabis. In fact, I'm not sure he has ever grown a high THC cannabis plant. Who knows? Maybe he has, but he certainly can't say that aloud in Utah!