DLI Flower stage photo periods

[The70’s]

Hello all, wondering about your strategies on the DLI for photoperiod flowering…

I plan on up-potting prior to flipping the light in the next 10days, once in flower i dont wanna be messing around with them too much, plus i will be using a trellis net.

Thanx for your input, btw i just started using the Photone app and my iphone.
After watching a few reputable reviewers, this is a super low cost addition to my grows

 

[The70’s]

Does this chart seem correct ? Is the number lower because of a 12hr lite cycle ??

 

[Delps8]

As high as you can get it. More light - more, better quality weed.

 

[Delps8]

Does this chart seem correct ? Is the number lower because of a 12hr lite cycle ??

There's no "correct" or "incorrect". growlightmeter.com and Shane at Migro recommend moderate light levels though neither source cites any research to back up their recommendations. Cannabis will give a good yield if you follow that chart.

And, if you follow that chart, your yield and quality levels will be lower than if you were to get your plants to their light saturation point as quickly as you can and keep them there.

Migro and growlightmeter.com are on the low end, most light manufacturers will recommend 600µmols in veg and 1k in flower, and researchers recommend at much light as the plants can take (the "light saturation point").

I give my grows at 850 - 1050 µmols, if possible, and it works out well.

 

[Weffalo]

Recently watched a video by Dr Bruce Bugbee doing an interview with Shane at Migro, I can't find a good source for where these DLI charts get there numbers so I'm with @Delps8 - I'd rather listen to proven experts who can cite scientific research. Essentially if you have high light you need higher C02 levels and nutrient uptake but if your plant is responding well to the light, I'm not sure there can be "too much" as long as it's within the acceptable range.

I'm testing this theory right now with my seedlings getting 40 DLI since day 1, they seem to both be responding absolutely fine it's just a question of will the increase in growth speed be worth the electricity cost or would they achieve approximately the same level of growth with only 10-12 DLI as recommended by these charts?

I'm yet to confirm any findings but if you'd like to listen to where I got this info and maybe learn somethings about DLI and lighting watch:

All the best.

 

[Weffalo]

Does this chart seem correct ? Is the number lower because of a 12hr lite cycle ??

Also DLI is Daily Light Integral, AKA the amount of light the plants receive in a 24 hour cycle, on a 12/12 schedule you would need higher intensity of light for the 12 hours to get the same DLI as 16:8 on a lower intensity.

1000 uMols @ 16 hours = DLI of 57
1000 uMols @ 12 hours = DLI of 43

I've got no idea why DLI is reduced for flowering because info on these topics seems sparse and not so well researched, but I am at the beginning of my journey with this stuff so someone else may be able to offer up insight as to why.

 

[The70’s]

The app is configured to calculate 12hr,18hr and 24hr, you just have to set it to your current light schedule.

I agree to push em, but being im a new grower and only on my second grow, i might do this in small incriments, meaning i will follow that chart by increasing the dli 5 incriments higher per cycle week, so if the chart says in my fourth week of flower I should be giving them 34dli, i’ll give em 40 and keep an eye on them…… if that makes sense

As i use my newly altered chart, it will probably be my new reference

 

[Delps8]

Also DLI is Daily Light Integral, AKA the amount of light the plants receive in a 24 hour cycle, on a 12/12 schedule you would need higher intensity of light for the 12 hours to get the same DLI as 16:8 on a lower intensity.

1000 uMols @ 16 hours = DLI of 57
1000 uMols @ 12 hours = DLI of 43

Which indicates that value of a grow environment where the plants can handle light >=1000µmols. I've grown only autos in the past 24 months (I did one photo grow in 2017) so giving the plants 900±µmols will give me a good DLI (20/4 photoperiod). I'm going to grow photos (well, a photo) next and I'll be trying to get my plants >1k because 12/12 is so much shorter than 20/4.

[tried to load ppfdcharts.com]

Shit, shit, shit. Looks like ppfdcharts.com is off the air - not a timeout just no dns entry. I was sorta wondering when that would happen - there was no evidence that LED Gardener was monetizing the site so it looks like "the kindness of his heart" ended this month. :-(

A couple of shortcuts for DLI - 100µmols for 20/4 results in a DLI of 7.2 That's handy for quick calculations - if your grow is getting about 700 µmols that tells you that the DLI is about 50. The decimal places do not matter and even ± a couple of mols does not matter. The reason I say that is that no plant has a perfectly flat canopy so taking a measurement at a few points in the canopy will only get you "in the ballpark" re. DLI - a vertical change of even a couple of inches dramatically changes the DLI.

Measuring and Tracking DLI
In veg and early flower, I measure PPFD in a grid a la back to front, left to right. I calculate the "row" and "column" averages as well as calculating the standard deviation for PPFD and/or STDEV. The STDEV indicates even the canopy is.

When colas start sticking up, I measure the PPFD at the top of each cola. You can give a cola too much light, BTW. I did that two grows ago and the top couple of inches of the cola bent away from the light. Interestingly, even though I reduced the PPFD for that cola, it didn't straighten out.
Veg and early flower

Flower - readings from the grow I just chopped. Two autos, Alice and Annie. Annie was about 4 times as big as Alice, the latter having had some problems as a seedling.

The Mars SP 3000 was lighting the front of the grow, the Vipar Spectra was for Alice, and the X3 is a "full cycle" (red heavy) spectrum.

The values in blue are a cue for me - they're getting a PPFD of < 500µmols which de Banco says is the minimum that you should give cannabis. That's a guideline, nothing more.

IIRC,

I've got no idea why DLI is reduced for flowering because info on these topics seems sparse and not so well researched, but I am at the beginning of my journey with this stuff so someone else may be able to offer up insight as to why.

I checked growlightmeter.com ("GLM") again and they continue to improve their site. They're now linking to other sources but not citing research means that they're offering opinions. Just like Shane at Migro.

Cutesy graphics like that look nice but what does it tell me? Not much, to be frank. It's their opinion of what DLI's should be used but offers nothing in the way of substantiating how they arrived at those values. I wrote Dominik, the programmer for Photone with whom I've corresponded when I tested Korona and Photone (I've been writing database driven business software for > 30 years, including 3 for Apple, so I have an understanding of the computing issues that he's dealing with) and he said that the only research that they've got is noted on the site. I did find one actual research paper cited but most of it is linking to other industry info. OK, opinions are interesting but my perspective is "money talks and bullshit walks" and unless there's data behind it, I put little faith in it.

The graphic also states that CO2 is "required" for some DLI's. Huh? Using "required" is a big red flag if the potential outcomes aren't discussed. This would be less of an opinion piece if there was some discussion about tradeoffs but, lacking that, "without data, it's just some other person on the internet with an opinion".

Another way to look at what they're recommending is to see how well it fits in with the underlying basic knowledge. We know that net photosynthesis ("Pn") increases as PPFD increases, understanding that the curve starts to roll off at about 500µmols.

With that in mind, why would reducing DLI, which will reduce the amount of glucose that the plant has for metabolism, tend to result in a "better" outcome (and then that takes us down the rabbit hole of how "better" is defined.)?

Rather than try to figure out what GLM is driving at, I'll stick with what Bugbee and others have documented and reproduced - increasing DLI results in a better crop, where better crop means increased plant quality and yield as well as increased crop quality and yield. If altering my light schedule and intensity will result in a better crop, I'm more than happy to makes those changes, but until then, I'm all in for "1000µmols or bust".

 

[Weffalo]

Which indicates that value of a grow environment where the plants can handle light >=1000µmols. I've grown only autos in the past 24 months (I did one photo grow in 2017) so giving the plants 900±µmols will give me a good DLI (20/4 photoperiod). I'm going to grow photos (well, a photo) next and I'll be trying to get my plants >1k because 12/12 is so much shorter than 20/4.

[tried to load ppfdcharts.com]

Shit, shit, shit. Looks like ppfdcharts.com is off the air - not a timeout just no dns entry. I was sorta wondering when that would happen - there was no evidence that LED Gardener was monetizing the site so it looks like "the kindness of his heart" ended this month. :-(

A couple of shortcuts for DLI - 100µmols for 20/4 results in a DLI of 7.2 That's handy for quick calculations - if your grow is getting about 700 µmols that tells you that the DLI is about 50. The decimal places do not matter and even ± a couple of mols does not matter. The reason I say that is that no plant has a perfectly flat canopy so taking a measurement at a few points in the canopy will only get you "in the ballpark" re. DLI - a vertical change of even a couple of inches dramatically changes the DLI.

Measuring and Tracking DLI
In veg and early flower, I measure PPFD in a grid a la back to front, left to right. I calculate the "row" and "column" averages as well as calculating the standard deviation for PPFD and/or STDEV. The STDEV indicates even the canopy is.

When colas start sticking up, I measure the PPFD at the top of each cola. You can give a cola too much light, BTW. I did that two grows ago and the top couple of inches of the cola bent away from the light. Interestingly, even though I reduced the PPFD for that cola, it didn't straighten out.
Veg and early flower

Flower - readings from the grow I just chopped. Two autos, Alice and Annie. Annie was about 4 times as big as Alice, the latter having had some problems as a seedling.

The Mars SP 3000 was lighting the front of the grow, the Vipar Spectra was for Alice, and the X3 is a "full cycle" (red heavy) spectrum.

The values in blue are a cue for me - they're getting a PPFD of < 500µmols which de Banco says is the minimum that you should give cannabis. That's a guideline, nothing more.

IIRC,

I checked growlightmeter.com ("GLM") again and they continue to improve their site. They're now linking to other sources but not citing research means that they're offering opinions. Just like Shane at Migro.

Cutesy graphics like that look nice but what does it tell me? Not much, to be frank. It's their opinion of what DLI's should be used but offers nothing in the way of substantiating how they arrived at those values. I wrote Dominik, the programmer for Photone with whom I've corresponded when I tested Korona and Photone (I've been writing database driven business software for > 30 years, including 3 for Apple, so I have an understanding of the computing issues that he's dealing with) and he said that the only research that they've got is noted on the site. I did find one actual research paper cited but most of it is linking to other industry info. OK, opinions are interesting but my perspective is "money talks and bullshit walks" and unless there's data behind it, I put little faith in it.

The graphic also states that CO2 is "required" for some DLI's. Huh? Using "required" is a big red flag if the potential outcomes aren't discussed. This would be less of an opinion piece if there was some discussion about tradeoffs but, lacking that, "without data, it's just some other person on the internet with an opinion".

Another way to look at what they're recommending is to see how well it fits in with the underlying basic knowledge. We know that net photosynthesis ("Pn") increases as PPFD increases, understanding that the curve starts to roll off at about 500µmols.

With that in mind, why would reducing DLI, which will reduce the amount of glucose that the plant has for metabolism, tend to result in a "better" outcome (and then that takes us down the rabbit hole of how "better" is defined.)?

Rather than try to figure out what GLM is driving at, I'll stick with what Bugbee and others have documented and reproduced - increasing DLI results in a better crop, where better crop means increased plant quality and yield as well as increased crop quality and yield. If altering my light schedule and intensity will result in a better crop, I'm more than happy to makes those changes, but until then, I'm all in for "1000µmols or bust".

Wow great info @Delps8 , thank you so much! I am glad you are here offering advice that stems from logical conclusions based on the expert advice of others and running your own practical tests and records to best achieve the correct lighting. I'm gonna read through your journals properly when I get a chance but I from glancing through I can already say thanks so much for documenting everything so thoroughly.

I'm probably gonna steal some of your methods for tracking DLI as I think that's a great metric to properly collect, my autos are currently getting around 55 DLI in late flower with some nugs probably achieving closer to 57+ so I'm very happy to see another user who doesn't subscribe to this notion of decreasing intensity just as the flowers are able to utilise it.

Very cool that you have reached out to GLM to verify the claims as well, I think it's an amazing app that they offer but ultimately this chart/DLI article seems to be more of a marketing gimmick based on opinion/broscience. I'll definitely be sticking with what both you and Dr Bruce Bugbee are saying for now until the evidence changes or I encounter any issues with too much light in my own grows.

 

[Weffalo]

The app is configured to calculate 12hr,18hr and 24hr, you just have to set it to your current light schedule.

I agree to push em, but being im a new grower and only on my second grow, i might do this in small incriments, meaning i will follow that chart by increasing the dli 5 incriments higher per cycle week, so if the chart says in my fourth week of flower I should be giving them 34dli, i’ll give em 40 and keep an eye on them…… if that makes sense

As i use my newly altered chart, it will probably be my new reference

Yeah can completely understand some trepidation, I am basically accepting there may be negative results from this one but I wanted to test if they really can handle that light and how the plants sizes compare to others at similar ages that grew under less light.

I think Delps charts offer some good insight as to what works well as he's clearly been there and done it. Increasing DLI over the stages works but it does seem like there's no reason to drop intensity after flip like the charts you linked suggest according to the scientific evidence.

 

[The70’s]

One undeniable thing is that increasing light requires increase in watering and nutrients which is where more data is needed.
Im hoping to record all the increases and see where it takes my grow, we may be talking about very small increases in yield and an increase in metabolism only to gain a small amount of yield. Im always suspicious

Its all good and interesting !

 

[Bill284]

One undeniable thing is that increasing light requires increase in watering and nutrients which is where more data is needed.
Im hoping to record all the increases and see where it takes my grow, we may be talking about very small increases in yield and an increase in metabolism only to gain a small amount of yield.

Its all good and interesting !

Merry Christmas my friend




#VIVOSUN #Love What You Grow
Bill284

 

[Delps8]

One undeniable thing is that increasing light requires increase in watering and nutrients which is where more data is needed.
Im hoping to record all the increases and see where it takes my grow, we may be talking about very small increases in yield and an increase in metabolism only to gain a small amount of yield. Im always suspicious

Its all good and interesting !

Got a kick out of your avatar - what vehicle is that? After a few years at Ft. Bragg (where the Air Force would drive us to work) my "daily driver" was a 113 as a FIST and then an M577 as an FDO. It was a great experience but eight years was enough.


You raise good points. More light increases demand for all other resources. Increased P allows a higher rate of respiration which will increase transpiration. That means water uptake increases which puts more water in the air and that means you've got to increase "wind", as Bugbee calls it. Essentially, if one of the inputs increases, you will tend to need to increases the rest of the inputs.

Also, any of those resources can be the "limiting" factor. I sat in on a thread with a grower who was getting light burn at 600µmols. Having light burn at that level just does not make sense - there's no such strain as "redhead"! By working through the components of the growing environment (below), the grower discovered that he had been watering incorrectly. His roots were getting waterlogged and the plant wasn't able to deal with even moderate amounts of light. It's always in the last place you look, right?

This graphic, a screenshot from one of this videos, helps me understand how it all works (I've never grown anything except cannabis).

Re. the increases - I think these images are in the Bugbee/Westmoreland video on hemp cultivation.

Plant morphology. My latest grow got mauled by thrips so I've decided that "dogshit" is a new descriptor for bud quality. Almost my entire grow was the"10" image. My previous grow looked at lot like "70". Check the pix in my journal for the 3/22 grow.

de Banco's source is "The Profitability of Growing Cannabis Under High Intensity Light". Google that and quite a few other documents popup, as well.

The conditions for this paper were that all plants were vegged at 600µmols and then the plants were exposed to different PPFD's. A large number of data is presented (grab a copy of the paper) but the yield data is shown here. Their yield values are low but the % change tells the story. What these researchers saw was an 8.5% increase going from 800µmols to 900µmols. That means about an extra ounce and a half if your yield is in the pound per grow range and it doesn't take a whole lot to get the increase. Yes, more ferts and other inputs are needed but, to me, that's part of the job.

Re. tracking - we can track tons of info but drawing accurate conclusions hard and from the data is very difficult due to the variability inherent in most growing environments. Researchers start with dozens of clones and grow them under highly controlled conditions. By comparison, a home grow is, in a word, chaos.

For me, there's so much variability in every grow that trying to pin down how one changed input changed the outcome is impossible. My approach has been to use the parameters graphic as a guide to try to optimize and simplify each part of the grow environment. I'm thinking is to put the pieces of the puzzle together as best I can and let the pointy head guys argue about the details.

 

[The70’s]

Got a kick out of your avatar - what vehicle is that? After a few years at Ft. Bragg (where the Air Force would drive us to work) my "daily driver" was a 113 as a FIST and then an M577 as an FDO. It was a great experience but eight years was enough.

Its an M88 recovery vehicle 60 tons, V12 twin turbo 32mph (downhill) top speed. I was a 63November M60A3 mechanic

 

[Delps8]

Its an M88 recovery vehicle 60 tons, V12 twin turbo 32mph (downhill) top speed

As soon as I saw "M88"… yeh, it came back to me. They're the answer to a stuck howitzer.

60 tons moving at 32 mph. Better than being in front of an M1 at full gallop!

And now, back to Shane and the Doctor.

 

[The70’s]

As soon as I saw "M88"… yeh, it came back to me. They're the answer to a stuck howitzer.

60 tons moving at 32 mph. Better than being in front of an M1 at full gallop!

And now, back to Shane and the Doctor.

The Hook

 

[Delps8]

Wow great info @Delps8 , thank you so much! I am glad you are here offering advice that stems from logical conclusions based on the expert advice of others and running your own practical tests and records to best achieve the correct lighting. I'm gonna read through your journals properly when I get a chance but I from glancing through I can already say thanks so much for documenting everything so thoroughly.

You're welcome. The info comes from resources that I've watched or downloaded and it's not well organized. I've got PDF's, pictures, screenshots, and video transcripts (text) that are accessible to me but, ATM, not publicly accessible.

I've gone back and forth on whether or not I want to change that. ATM, my "GAS gauge" is on an ebb, I'll admit ("GAS" = "give a shit" == this last grow sorta took the wind out of my sails).

I'm probably gonna steal some of your methods for tracking DLI as I think that's a great metric to properly collect, my autos are currently getting around 55 DLI in late flower with some nugs probably achieving closer to 57+ so I'm very happy to see another user who doesn't subscribe to this notion of decreasing intensity just as the flowers are able to utilise it.

Please do. And repost if you tweak it into something else.

Very cool that you have reached out to GLM to verify the claims as well, I think it's an amazing app that they offer but ultimately this chart/DLI article seems to be more of a marketing gimmick based on opinion/broscience. I'll definitely be sticking with what both you and Dr Bruce Bugbee are saying for now until the evidence changes or I encounter any issues with too much light in my own grows.

I contacted GLM because I tested their app "Korona" when I unarchived my grow tent in early 2021. I bought a tent setup back in 2017, had a photo grow that revegged when I got hit by one of Southern California's famous blackouts and screwed up the (mechanical) light timer. After I ended up with a tent full of nothing, I packed it up until 2/21.

When I unarchived my tent, I tested Korona on my iPhone XS Max running against a Kind LED blurple and Korona could not give me a number. I contacted the company and their programmer made a few suggestions, to no avail. Seeing that I'm a programmer myself (I've been writing software for a living for 30+ years), we discussed a few of the issues that they're facing with Korona, now "Photone", and I moved on and bought an Apogee.

This Spring, I traded email with them again. From those emails:

Delps8 - "I'm writing this in response to a question on <a site dedicated to growing auto flower cannabis>. The issue is that your DLI graph shows that recommended DLI drops from 45 moles in late veg to 25 moles in early flower. I've spent quite a bit of time reading research papers but can't find a reference that indicates that DLI should drop. The info that I've been reading is research on how cannabis responds to increased DLI so their focus is on establishing and maintaining high light levels. Can you provide additional information about dropping DLI in early flower?"

GLM - "The sources of research can be found on the bottom of our articles which is this one: Cannabis DLI for Your Full Grow Cycle
The background generally is light stress: Running the lights at a PPFD of 700 at 18 hours produces a DLI of 45 (the veg target) and then dropping the photoperiod to 12 hours on the same intensity equates to a DLI of around 30 which can then be increased (the PPFD) as the plants get more mature and are better acclimated to high light levels. Staying on the same DLI would require a way higher light intensity that may burn the plants at such an early stage."

Delps8 - "Got it — the drop is because of the change in the light schedule. I can see how that works for photoperiod cannabis but what about autoflowers?"

GLM - "From my understanding auto-flowers can be treated as being “always in veg” so I’d stick to a DLI of 45 until harvest."

That's the reason — hundreds or perhaps thousands of growers are running their autos at 45 mols because the programmer thought that 45 mols was a good number because he thinks that autos are "always in veg".

As I try to tell family members about "stuff on the internet" - "Whether it's a picture, a movie, an email or whatever, it is not real. It is just dots on the screen. You have no idea who or what put it there and you have no idea if it's true or even real. It is just dots on the screen."

Some people will understand what I mean about "dots on the screen" but some people will follow the recommendation to run autos at 45 mols because the guy who thinks that "[autos are] always in veg" recommended it*.

Yup, it's turtles all the way down.

*another issue being that there's zero research backing up using 43 mols in veg to begin with.

 

[Keffka]

With increased transpiration you’re going to want to increase your K as well as your P.. K regulates the stomata opening and closing. Be careful when adding P though.. Too much P can kill off and discourage myco growth. Myco can provide by some estimates up to 80% of your plants P requirement since myco is the number one releaser of P.. it’s a fine dance you want to play and the harder you push your plants light wise the finer the dance is. If you’re growing synthetically this shouldn’t be an issue and should just be a matter of increasing nutes.. if you’re growing organically it’ll take some trial and error since organic doesn’t typically like to be pushed to the light limit to begin with.

@Delps8 is a good person to bounce light questions off of.. introduced me to the works of Dr Bugbee actually