Exactly what does "over 40 (moles) begins to hit a point of diminishing returns for your crop" mean?

[IamN2pot]

First, a HUGE thank-you to the THCF members that have enlightened me greatly about PAR and PPFD (yes, pun intended💡). That said, I may still have knucklehead ideas about what I think I've learned, so feel free to step in and correct me, again!!!.
All of the info I've been reading about how much light a cannabis plant needs goes along these lines. They need a minimum and 20 moles of light and up to 40 moles max per day, 18hr or 12hr, doesn't matter as long as it's a total of 20-40 moles a day. Total amounts of light "over 40 begins to hit a point of diminishing returns for your crop."
Now, I'm thinking that the 40 moles per day is the sweet spot and the term "diminishing returns" means a smaller total volume of flower, just like flowers that receive less than 40 moles per day will begin to render "diminishing returns". But then I wonder to myself, is that term being used commercially? Is it refering to a diminishing return more along financial lines of cost per gram to produce (profit margin diminishing)?

The reason I am asking that question is because IF the maximum amount of light is 40 moles, and bud size diminishes at light concentration over that, then I have questions and ideas about how LED lights are designed. In a perfect cannabis light, wouldn't ALL the PPFD measurements on a PPFD map read about 900umols? ..for a perfectly even maximum canopy coverage?

I think I must have something wrong because there are alot of PPFD maps that have the center area mapped at way over 900umols and the outside edges well under 450umols. Do both of those areas of the grow tent, over 900 and under 450umols, have equally diminishing returns?

TIA for your help and answers, N2

 

[growsince79]

First, a HUGE thank-you to the THCF members that have enlightened me greatly about PAR and PPFD (yes, pun intended💡). That said, I may still have knucklehead ideas about what I think I've learned, so feel free to step in and correct me, again!!!.
All of the info I've been reading about how much light a cannabis plant needs goes along these lines. They need a minimum and 20 moles of light and up to 40 moles max per day, 18hr or 12hr, doesn't matter as long as it's a total of 20-40 moles a day. Total amounts of light "over 40 begins to hit a point of diminishing returns for your crop."
Now, I'm thinking that the 40 moles per day is the sweet spot and the term "diminishing returns" means a smaller total volume of flower, just like flowers that receive less than 40 moles per day will begin to render "diminishing returns". But then I wonder to myself, is that term being used commercially? Is it refering to a diminishing return more along financial lines of cost per gram to produce (profit margin diminishing)?

The reason I am asking that question is because IF the maximum amount of light is 40 moles, and bud size diminishes at light concentration over that, then I have questions and ideas about how LED lights are designed. In a perfect cannabis light, wouldn't ALL the PPFD measurements on a PPFD map read about 900umols? ..for a perfectly even maximum canopy coverage?

I think I must have something wrong because there are alot of PPFD maps that have the center area mapped at way over 900umols and the outside edges well under 450umols. Do both of those areas of the grow tent, over 900 and under 450umols, have equally diminishing returns?

TIA for your help and answers, N2

Totally depends on the plants and environment. Some plants can handle more light than others. Will 400umole make better than 1300? Who knows, maybe you should do a side by side and see. I doubt you can draw a symmetrical curve.

 

[Anthem]

First, a HUGE thank-you to the THCF members that have enlightened me greatly about PAR and PPFD (yes, pun intended💡). That said, I may still have knucklehead ideas about what I think I've learned, so feel free to step in and correct me, again!!!.
All of the info I've been reading about how much light a cannabis plant needs goes along these lines. They need a minimum and 20 moles of light and up to 40 moles max per day, 18hr or 12hr, doesn't matter as long as it's a total of 20-40 moles a day. Total amounts of light "over 40 begins to hit a point of diminishing returns for your crop."
Now, I'm thinking that the 40 moles per day is the sweet spot and the term "diminishing returns" means a smaller total volume of flower, just like flowers that receive less than 40 moles per day will begin to render "diminishing returns". But then I wonder to myself, is that term being used commercially? Is it refering to a diminishing return more along financial lines of cost per gram to produce (profit margin diminishing)?

The reason I am asking that question is because IF the maximum amount of light is 40 moles, and bud size diminishes at light concentration over that, then I have questions and ideas about how LED lights are designed. In a perfect cannabis light, wouldn't ALL the PPFD measurements on a PPFD map read about 900umols? ..for a perfectly even maximum canopy coverage?

I think I must have something wrong because there are alot of PPFD maps that have the center area mapped at way over 900umols and the outside edges well under 450umols. Do both of those areas of the grow tent, over 900 and under 450umols, have equally diminishing returns?

TIA for your help and answers, N2

Go to you tube and look up Bruce Bughee. There is a video of him and in the cover of the you tube title he is in a lab coat. He explains the formula for changing u miles to moles

 

[IamN2pot]

Go to you tube and look up Bruce Bughee. There is a video of him and in the cover of the you tube title he is in a lab coat. He explains the formula for changing u miles to moles

Thanks for the Dr. B video input. There is a converter online to do that, here. 900umols per second adds up to 38.88 moles during 12 hours of light... so right around 900umols is the sweet spot, I think???

 

[mysticepipedon]

"Diminishing returns" doesn't mean more light will reduce yield, it just means increasing light by an increment won't increase yield as much as the last increment. The yield curve with increasing light is starting to flatten out. Eventually it will decrease yield.

 

[N1ghtL1ght]

from a study on that topic.

I know it's bizarre but the real loss of efficiency in photosynthesis is not matched with an actual decrease in harvest, as grow experiments have shown a rather linear increase.

It could be the extra amount in sugar caused higher surplus growth, when usually some is needed to satisfy the demand of the living cells already.

 

[effexxess]

Do both of those areas of the grow tent, over 900 and under 450umols, have equally diminishing returns?

Here is a study showing nature of diminishing returns graphed out. You can see how the yield curve is still climbing at 450 and flattens after 900.

High light intensities can be used to grow healthy and robust cannabis plants during the vegetative stage of indoor production (2021)​

Melissa Moher, David Llewellyn, Max Jones and Youbin Zheng

Abstract. Although the vegetative stage of indoor cannabis production can be relatively short in duration, there is a high energy demand due to higher light intensities (LI) than the clonal propagation stage and longer photoperiods than the flowering stage (i.e., 16 – 24 hours vs. 12 hours). … To determine the vegetative plant responses to LI, clonal plants of ‘Gelato’ were grown for 21 days with canopy-level photosynthetic photon flux densities (PPFD) ranging between 135 and 1430 μmol·m-2·s-1 on a 16-hour photoperiod (i.e., DLI daily light integrals of ≈ 8 to 80 mol·m-2·d-1). Plant height and growth index responded quadratically; the number of nodes, stem thickness, and aboveground dry weight increased asymptotically; and internode length and water content of aboveground tissues decreased linearly with increasing LI. … Generally, PPFD levels of ≈ 900 μmol·m-2·s-1 produced compact, robust plants that are commercially relevant, while PPFD levels of ≈ 600 μmol·m-2·s-1 promoted plant morphology with more open architecture – to increase airflow and reduce the potential foliar pests in compact (i.e., indica-dominant) genotypes.

There was almost a 3-fold increase in DW (dry weight) over the 135 to 1430 μmol·m-2·s-1 APPFD range in the present study, although 90% of the maximum increase in DW was attained at an APPFD of only ≈ 900 μmol·m-2·s-1.

In contrast, plants were smaller at ≈ 900 vs. 600 μmol·m-2·s-1 but had ≈ 15% higher DW and ≈ 6% thicker stems (i.e., ≈ 13% higher cross-sectional area).

Since the number of nodes saturated at relatively low LI, a canopy-level PPFD target of about 900 μmol·m-2·s-1 may be most appropriate for producing robust but not overly compact plants while also minimizing lighting-related energy and infrastructure costs. Although not as common in commercial settings, production facilities that target more open plant architecture and greater energy conservation may opt for canopy-level PPFD target of ≈ 600 μmol·m-2·s-1.

Few contemporary recommendations suggest exposing vegetative cannabis plants to PPFDs higher than 800 μmol·m-2·s-1 in indoor production systems. The current study demonstrates that vegetative cannabis can be exposed to substantially higher LIs (than commonly-used in the industry) with positive morphological outcomes that can prime plants for the transition into the flowering phase.


Note: "Blurple light" spectrum LEDs used for study!

F igure 1. Relative spectral photon flux distribution of blue (B) and red (R) LEDs used during the propagation and vegetative stages

 

[IamN2pot]

I know it's bizarre but the real loss of efficiency in photosynthesis is not matched with an actual decrease in harvest, as grow experiments have shown a rather linear increase.

Bizarre indeed. THanks for the info!

 

[IamN2pot]

Here is a study showing nature of diminishing returns graphed out. You can see how the yield curve is still climbing at 450 and flattens after 900.

High light intensities can be used to grow healthy and robust cannabis plants during the vegetative stage of indoor production (2021)​

Melissa Moher, David Llewellyn, Max Jones and Youbin Zheng

Abstract. Although the vegetative stage of indoor cannabis production can be relatively short in duration, there is a high energy demand due to higher light intensities (LI) than the clonal propagation stage and longer photoperiods than the flowering stage (i.e., 16 – 24 hours vs. 12 hours). … To determine the vegetative plant responses to LI, clonal plants of ‘Gelato’ were grown for 21 days with canopy-level photosynthetic photon flux densities (PPFD) ranging between 135 and 1430 μmol·m-2·s-1 on a 16-hour photoperiod (i.e., DLI daily light integrals of ≈ 8 to 80 mol·m-2·d-1). Plant height and growth index responded quadratically; the number of nodes, stem thickness, and aboveground dry weight increased asymptotically; and internode length and water content of aboveground tissues decreased linearly with increasing LI. … Generally, PPFD levels of ≈ 900 μmol·m-2·s-1 produced compact, robust plants that are commercially relevant, while PPFD levels of ≈ 600 μmol·m-2·s-1 promoted plant morphology with more open architecture – to increase airflow and reduce the potential foliar pests in compact (i.e., indica-dominant) genotypes.

View attachment 1284296

There was almost a 3-fold increase in DW (dry weight) over the 135 to 1430 μmol·m-2·s-1 APPFD range in the present study, although 90% of the maximum increase in DW was attained at an APPFD of only ≈ 900 μmol·m-2·s-1.

In contrast, plants were smaller at ≈ 900 vs. 600 μmol·m-2·s-1 but had ≈ 15% higher DW and ≈ 6% thicker stems (i.e., ≈ 13% higher cross-sectional area).

Since the number of nodes saturated at relatively low LI, a canopy-level PPFD target of about 900 μmol·m-2·s-1 may be most appropriate for producing robust but not overly compact plants while also minimizing lighting-related energy and infrastructure costs. Although not as common in commercial settings, production facilities that target more open plant architecture and greater energy conservation may opt for canopy-level PPFD target of ≈ 600 μmol·m-2·s-1.

Few contemporary recommendations suggest exposing vegetative cannabis plants to PPFDs higher than 800 μmol·m-2·s-1 in indoor production systems. The current study demonstrates that vegetative cannabis can be exposed to substantially higher LIs (than commonly-used in the industry) with positive morphological outcomes that can prime plants for the transition into the flowering phase.


Note: "Blurple light" spectrum LEDs used for study!
View attachment 1284297
F igure 1. Relative spectral photon flux distribution of blue (B) and red (R) LEDs used during the propagation and vegetative stages

Now I see. If I'm reading that graft right, the "diminishing return" is a "smaller bang for your buck" commercially speaking. It is NOT leading to smaller buds or total weight. It looks like the total yield continues to increase up to around 1500umols or 60 moles in a 12/12 bloom cycle? Am I on the right track there?

 

[N1ghtL1ght]

It is NOT leading to smaller buds or total weight. It looks like the total yield continues to increase up to around 1500umols or 60 moles in a 12/12 bloom cycle?

the study you are refering to did only veg, not flower, plants.

 

[effexxess]

the study you are refering to did only veg, not flower, plants.

Flowering study summary and links below 🙂

​

Cannabis Yield, Potency, and Leaf Photosynthesis Respond Differently to Increasing Light Levels in an Indoor Environment 2021​

Victoria Rodriguez-Morrison, David Llewellyn and Youbin Zheng​

The objectives of this study were to establish the relationships between canopy-level LI (light intensity), leaf-level photosynthesis, and yield and quality of drug-type cannabis. … Plants were grown for 12 weeks in a 12-h light/12-h dark ‘flowering’ photoperiod under canopy-level PPFDs ranging from 120 to 1800 μmol·m-2·s-1 provided by light emitting diodes.

… dry inflorescence yield increased linearly with increasing canopy-level PPFD up to 1,800 μmol·m−2·s−1, while leaf-level photosynthesis saturated well-below 1,800 μmol·m−2·s−1. The density of the apical inflorescence and harvest index also increased linearly with increasing LI, resulting in higher-quality marketable tissues and less superfluous tissue to dispose of. There were no LI treatment effects on cannabinoid potency, while there were minor LI treatment effects on terpene potency

FIGURE 1 | Relative spectral photon flux distribution of Pro650 (Lumigrow) light-emitting diode (LED) fixtures.
“Blurple” light. The photon flux ratio of B (400–500 nm), green (G, 500–600 nm), and R (600–700 nm) was B18:G5:R77.

It was predicted that cannabis yield would exhibit a saturating response to increasing LI, thereby signifying an optimum LI range for indoor cannabis production. However, the yield results of this trial demonstrated cannabis’ immense plasticity for exploiting the incident lighting environment by efficiently increasing marketable biomass up to extremely high—for indoor production—LIs (Figure 7A). Even under ambient CO2, the linear increases in yield indicated that the availability of PAR photons was still limiting whole-canopy photosynthesis at APPFD levels as high as ≈1,800 μmol·m−2·s−1 (i.e., DLI ≈78 mol·m−2·d−1).

FIGURE 6 | Sketches of Cannabis sativa ‘Stillwater’ plants grown under low (A) and high (B) photosynthetic photon flux density (APPFD), 9 weeks after initiation of 12-h photoperiod

Overall, the impact that increasing LI had on cannabis morphology and yield were captured holistically in the plant sketches in Figure 6, which shows plants grown under higher LIs had shorter internodes, smaller leaves, and much larger and denser inflorescences (resulting in higher harvest index), especially at the plant apex.

Increasing Light Intensity Enhances Inflorescence Quality. Beyond simple yield, increasing LI also raised the harvest quality through higher apical inflorescence (also called “cola” in the cannabis industry) density—an important parameter for the whole-bud market—and increased ratios of inflorescence to total above ground biomass (Figures 7B,C).

FIGURE 7 | The relationship between average apical photosynthetic photon flux density (APPFD) applied during the flowering stage (81 days) and inflorescence dry weight (A), harvest index (total inflorescence dry weight / total aboveground dry weight) (B), and apical inflorescence density (based on fresh weight) (C) of Cannabis sativa ‘Stillwater’. Each datum is a single plant.

CONCLUSION. The results also indicate that the relationship between LI and cannabis yield does not saturate within the practical limits of LI used in indoor production. Increasing LI also increased harvest index and the size and density of the apical inflorescence; both markers for increasing quality. However, there were no and minor LI treatment effects on potency of cannabinoids and terpenes, respectively.

 

[IamN2pot]

CONCLUSION. The results also indicate that the relationship between LI and cannabis yield does not saturate within the practical limits of LI used in indoor production. Increasing LI also increased harvest index and the size and density of the apical inflorescence; both markers for increasing quality. However, there were no and minor LI treatment effects on potency of cannabinoids and terpenes, respectively.

I think that pretty well answers my question about a light saturation point and so called "diminishing return". Thank you to both @effexxess and @N1ghtL1ght for you patience with me and your knowledge. I really appreciate it! 👍

OK, so I have to ask 1 more question. I see good data above on how many or dense a photon shower the plants can handle and thrive under in both veg and bloom stages, about 1500umols at canopy in veg and up to 1800umols and more in bloom. Below I attached a PPFD map of my SF4000 and it has measuements at 12", 18", and 22" while the newest SE5000 shows a map at 8" and 10".
I've also been learning about LED light burn, appearently from the light being to close to the canopy and not the heat given off, ...soooo? You know where this is going. Only in the 12" map of my SF4000 do those PPFD numbers exceed 1800umols. The SE5000 doesn't even break 1400umols on the 10" map. So the question is, where is that happy spot? My guess is it is NOT in the 8"-12" over the canopy range, but that's why I'm asking. Maybe it is for the SE5000, but not for the SF4000? I was thinking that for my SF4000 in a 4x4 tent, that the 22" numbers would give me my best bud size, density and overall weight, because that map shows the largest 'total' area under the lamp with PPFD reading above 450umols and I would certainly hope be far enough away from the canopy to avoid any light burn issues. Should I be going the other direction, towards the largest area with 900+umols? Trying to get as high a PPFD as I dare in the center and forget about the edges? Where is that sweet spot??? without causing "LED light burn" issues?

OK. that was more than 1 question mark, but thanks anyway!!! 🙃💡☮️

 

[RootsRuler]

IME, 900 - 1000umols is the sweet spot in veg and 1200 - 1600 umols in flower. 900umol is almost 40,000 Lux.

Of course much of this is also dependent on room environment. Pushing 1600umol is going to create a lot of heat regardless of the cooler running LED's. Anything higher in Umol will burn the canopy unless you have high air exchange rates and air conditioning that can cool down the environment to a workable temperature.

What I would like to see from lighting fixture companies is to use more LED's towards the edges of the lights so that you get a more uniform PPFD across the whole light fan.

For example, the SF4000...

Nominal run height would be around 18" so I will use the map provided. At center it is putting out close to 1400 ppfd. At the edge it is putting out around 450 ppfd. Adding more LED/psi at the edges would increase PPFD at those zones. Of course this would mean that COB manufacturers would have to construct and designate each panel in a specific configuration to correspond to where it is in the fixture. Not a big deal but much easier to just put an even amount on each panel and call it a day since each panel is the same and they don't have to make and track four different panels.

If there was a manufacturer that was willing to do this I would seriously consider buying their light.

 

[IamN2pot]

IME, 900 - 1000umols is the sweet spot in veg and 1200 - 1600 umols in flower. 900umol is almost 40,000 Lux.

Of course much of this is also dependent on room environment. Pushing 1600umol is going to create a lot of heat regardless of the cooler running LED's. Anything higher in Umol will burn the canopy unless you have high air exchange rates and air conditioning that can cool down the environment to a workable temperature.

What I would like to see from lighting fixture companies is to use more LED's towards the edges of the lights so that you get a more uniform PPFD across the whole light fan.

For example, the SF4000...

Nominal run height would be around 18" so I will use the map provided. At center it is putting out close to 1400 ppfd. At the edge it is putting out around 450 ppfd. Adding more LED/psi at the edges would increase PPFD at those zones. Of course this would mean that COB manufacturers would have to construct and designate each panel in a specific configuration to correspond to where it is in the fixture. Not a big deal but much easier to just put an even amount on each panel and call it a day since each panel is the same and they don't have to make and track four different panels.

If there was a manufacturer that was willing to do this I would seriously consider buying their light.

Reading my mind. I have to believe there is something wrong with my simplistic thinking. So why wouldn't one use a square bar design fixture to go into a square tent to get even PPFD readings across the map? It must be easier said than done. My idea is a design like this one, and of course, no PPFD map for it.

 

[N1ghtL1ght]

First off, just because you CAN give the plant so much light doesn't mean we want to do that, or if we do, at all times.

Light translates to sugar --> biomass, but not necessarily trichomes. High light mostly causes dense, swollen buds that weigh heavy, but its quality may already suffer from the 'Dilution-Effect'.

Most "bleaching" you see on top is actually a misdiagnosed deficiency. Light acts as a metabolic driver, high lights needs more nutes than lower. The PPFD affects a large number of variables that need to be considered.

 

[RootsRuler]

Reading my mind. I have to believe there is something wrong with my simplistic thinking. So why wouldn't one use a square bar design fixture to go into a square tent to get even PPFD readings across the map? It must be easier said than done. My idea is a design like this one, and of course, no PPFD map for it.

I got to talk to some of the engineers at California Lightworks and asked them why the center is always the highest PPFD and the edges the lowest. They explained it to me this way.

Each LED puts out the same amount of PPFD. Those LED's are either built with a refractor as part of the design or they augment it with a refractor that will spread the fan of the LED since raw LED's emit a single beam. Because each LED has a particular angle of fan the center ones get the benefit of the fan from the others which ups the PPFD readings. Essentially the center of the light is being showered with electrons while the edges don't have the advantage of the other diodes adding electrons into their light fan as much. That's why you see the PPFD go down exponentially as you move to the outer edge of the light.

You can remedy this by adding a light next to it or near it to supply the edge with enough crossover fan light but now you need more room and the outer edge of the added light still suffers the same issue. This is why I say that tailoring the light so that the output is as even as possible throughout the light footprint would be a boon to tent growers like me. With a light like this I can do a wall to wall SCROG in the tent and not have to accept that the farther out I go from the center of the lamp the smaller my yields will be.

A bar light like the SE5000 could be made to have the 2 end bars have double or triple the amount of LEDs while the bars inside next to the outer bars would have less and the center even less. Both ends of each of these inner bars would also have to have more LED's to be able to have the light power like the outside bars do so that all four walls are getting the same light coverage.

I'm no electrical engineer and I'm sure there is some sort of physics law that prohibits this but it seems that a light like this is what would be most beneficial to us tent growers.

Light translates to sugar --> biomass, but not necessarily trichomes. High light mostly causes dense, swollen buds that weigh heavy, but its quality may already suffer from the 'Dilution-Effect'.

Most "bleaching" you see on top is actually a misdiagnosed deficiency. Light acts as a metabolic driver, high lights needs more nutes than lower. The PPFD affects a large number of variables that need to be considered.

While your statement is true there is some context that needs to be availed.

Yes, high PPFD will create dilution effect BUT that depends on earlier development of your nutrient delivery system, i.e. Branches, and your root system. If you take the time to develop a strong root and branch system your plant will be up to being able to deliver the nutrients it needs to avoid the dilution effect and produce heavy , swollen DANK flower. The one thing I would be a bit apprehensive about would be the heat the high PPFD would generate which might evaporate some of the terpenes giving a less than enjoyable experience.

 

[N1ghtL1ght]

I got to talk to some of the engineers at California Lightworks and asked them why the center is always the highest PPFD and the edges the lowest. They explained it to me this way.

Each LED puts out the same amount of PPFD. Those LED's are either built with a refractor as part of the design or they augment it with a refractor that will spread the fan of the LED since raw LED's emit a single beam. Because each LED has a particular angle of fan the center ones get the benefit of the fan from the others which ups the PPFD readings. Essentially the center of the light is being showered with electrons while the edges don't have the advantage of the other diodes adding electrons into their light fan as much. That's why you see the PPFD go down exponentially as you move to the outer edge of the light.

You can remedy this by adding a light next to it or near it to supply the edge with enough crossover fan light but now you need more room and the outer edge of the added light still suffers the same issue. This is why I say that tailoring the light so that the output is as even as possible throughout the light footprint would be a boon to tent growers like me. With a light like this I can do a wall to wall SCROG in the tent and not have to accept that the farther out I go from the center of the lamp the smaller my yields will be.

A bar light like the SE5000 could be made to have the 2 end bars have double or triple the amount of LEDs while the bars inside next to the outer bars would have less and the center even less. Both ends of each of these inner bars would also have to have more LED's to be able to have the light power like the outside bars do so that all four walls are getting the same light coverage.

I'm no electrical engineer and I'm sure there is some sort of physics law that prohibits this but it seems that a light like this is what would be most beneficial to us tent growers.

It is just due to crosslighting, this is also dependant on distance to canopy. Once close up like 20-30cm it alleviates and homogenizes the light dustribution better.

The solution thought out by SANlights system (to prevent the typical hotspot and increase ppfd uniformity) is to use 2 lamps (instead of one), place them a bit towards the sides, but slightly tilted/directed towards the center:

Lichtmessung

bloomtech.de

Yes, high PPFD will create dilution effect BUT that depends on earlier development of your nutrient delivery system, i.e. Branches, and your root system

Well, my last run did confirm that is not necessary. The plants were able to develop big buds even with almost no veg (cut >> root >> flower). In 3 months they are able to do that easily. Although it surely help to enter flower well-prepared. But then roots can only drink when they are new, so a plant's roots always grows.

being able to deliver the nutrients it needs to avoid the dilution effect and produce heavy , swollen DANK flower.

and exactly this causes the dilution effect - pumping flowers to be heavy with nutes. I'm aiming to grow trichomes, not inert dry plant matter.
Thus, I need a high area of flower surface, but the buds itself shall be light, and a smooth original smoke.
Problem with fertilizer in abundancy is the occassional darkgreen sugarleaf, causing bitterness/sharpness & hayish taste. Apart from the tendency of Cannabis to accumulate metals and such in its tissue.

 

[RootsRuler]

It is just due to crosslighting, this is also dependant on distance to canopy. Once close up like 20-30cm it alleviates and homogenizes the light dustribution better.

The solution thought out by SANlights system (to prevent the typical hotspot and increase ppfd uniformity) is to use 2 lamps (instead of one), place them a bit towards the sides, but slightly tilted/directed towards the center:

Lichtmessung

bloomtech.de

Thank You! This sounds like it will better my light coverage. I have 2 lights in a 5 x 5. I will try this and measure light uniformity across the canopy! 🤘

 

[RootsRuler]

It is just due to crosslighting, this is also dependant on distance to canopy. Once close up like 20-30cm it alleviates and homogenizes the light dustribution better.

The solution thought out by SANlights system (to prevent the typical hotspot and increase ppfd uniformity) is to use 2 lamps (instead of one), place them a bit towards the sides, but slightly tilted/directed towards the center:

Lichtmessung

bloomtech.de

I was so sure that your solution was what I have been looking for but I ran into a few issues.

I slid the roof bars over to the side to mount the lights and tilted them at around 45* so that the center of the light was pointed at the center of the canopy. What I got initially was if I hung the light almost touching the wall it lit the edges beautifully but the PPFD dropped precipitously once it got about a third of the way from the wall. I tried to move the light bar and light closer to the center to increase the PPFD but the edges then suffered a drop in PPFD. More than likely it's my lights as one is an old school style blurple and the other is a newer COB style lamp. In my situation I think it could work if I had a 3rd light and hung it directly in the middle hanging in the normal position horizontally then have the other 2 lights at a slight angle at the edges like you posted. This configuration would give me wall to wall coverage at an acceptable PPFD reading for flower. I'm growing in a 5 x 5.

 

[IamN2pot]

I'm aiming to grow trichomes, not inert dry plant matter.

LOL, N1L1, I completely agree. Between my e-nail that gets 95% of my usage and the S & B Plenty for the occasion when I feel like an hour long flower session, my lungs and bronchial tubes are seriously improved over when I smoked alot of plant matter.

Well, my last run did confirm that is not necessary. The plants were able to develop big buds even with almost no veg (cut >> root >> flower).

Please elaborate with some additional tips. Canopy light intensity numbers? Hydro? Soil? Nute regime?
Reason that perked my interest is because back in the day, mid 90's while I was in A-dam, I was growing the NL5xHaze in a SOG. What was differant about the NL5xHaze was/is that as soon as I rooted clones under 24/0, I planted them into pots (soil) and put them under 12/12, where they remained for 80-83 days. Most other commercial growers back then opted for as short a bloom time as possible and would do a 10 day 24/0 to veg plants before flipping to 12/12 in SOG grows. I was running 600w HPS w/90K lums over 42 plants, 6pots x 7pots, and pots were about 6" square. In those days and in that SOG system, we aimed for dry weight of 500gr pr sq meter under the 600w lamps.
What a differance today from 30 years ago in our understanding of this plant and it's needs!