My bad I just saw your after water pic.. could’ve just been thirst I saw instead of temps
High dli for autoflowers
- Thread starter browntrout1
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browntrout1
420 Member
Week 9 of 12
Yeah you’re right in that zone. Coloring is typical for your stage.
45 is a better choice since you’re running 24/0. If you’re not gonna give them a break you need to ride the line pretty close.
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browntrout1
420 Member
Thanks this is good info,really appreciate it
No problem! Like everything else in life, take the information you get and apply it in a way that works best for you. Some times you’ll get conflicting information and both pieces will be true. That’s because there are so many different methods, environments, strains, etc. that what works for you might kill my plants and vice versa.
You know your grow better than anyone. Trust your gut.
to the forum 
I see your getting some advice already 
Delps8
Well-Known Member
I tested Photone, then called "Korona", back in 2021 and then again in 2022. As a result of the initial test,I use an Apogee and have a Uni-T lux meter. There are numerous reports of Photone being inaccurate; interestingly the reports are that it reads high.
My first test, was against a blurple and Korona could not generate a result. Second test, Photone as 16% high. In the first test, the weight of the paper had not yet been specified so I tested 20, 22, and 24 lb papers and sent the results to the programmer. They now, apparently, give specific advice.
Most of the time, I use the Apogee since it's probably less inaccurate than the lux meter + conversion. There are times when I spot check with the Uni-T because it's easier to use. I didn't take light readings yesterday, for example, but some of the colas in my grow are close to 1kµmol. It was very easy to put the Uni-T in the tent and get a quick read. It was 6200± lux which, for that light, works out to 992µmol. Good to go.
Delps8
Well-Known Member
A DLI of 45mol with a photoperiod of 24 hours is an average PPFD of just over 500µmol. The light saturation point for a cannabis plant is considered 800-1000µmol.
I run both autos and photos at 1kµmol± because cannabis thrives at those light levels and higher, in ambient CO2. Using that much light assumes that light is the limiting factor meaning that the rest of your grow has to be in good shape. I understand that autos are photos that have been ruderalis genes introduced but have not seen evidence that autos cannot thrive at the 800-1kµmol level.
The only two times I've seen grows that cannot support 400-500µmol were soil grows where the soil was hydrophobic due to incorrect watering.
In my current grow, my plant was at 496µmol on day 21 andI try to keep it in the mid-900's to mid-1kµmol.
Re. 45 for autos as recommended by growlightmeter.com — as best I can tell, the light compensation point for cannabis is 64µmol so light levels between 64 and 800-1kµmol will sustain growth. When I contacted the Photone programmer and asked for citations about the recommended light levels, the response to my question about autos was that they consider autos to be "always in veg" so they recommend 45µmol. I did not seek to understand why he would consider a plant that is flowering to be in veg.
In terms of what light levels to use in my grows, I initially based my practices on data presented by Dr. Bugbee which was very similar to the data presented in the Chandra paper (attached). The results in the Chandra paper were interesting but the focus is on net photosynthesis ("P") and it didn't sit 100% well with me that P was a valid proxy for yield. It took about another two grows before I found the Frontiers paper.
In the paper "Cannabis Yield, Potency, and Leaf Photosynthesis Respond Differently to Increasing Light Levels in an Indoor Environment" the authors write:
"These works have demonstrated that cannabis leaves have very high photosynthetic capacity. However, they have limited use in modeling whole canopy photosynthesis or predicting yield because single-leaf photosynthesis is highly variable; depending on many factors during plant growth such as: leaf age, their localized growing environments (e.g., temperature, CO2, and lighting history), and ontogenetic stage (Murchie et al., 2002; Zheng et al., 2006; Carvalho et al., 2015; Bauerle et al., 2020). While lighting vendors have long relied on cannabis leaf photosynthesis studies to sell more light fixtures to cannabis growers, their models are only tangentially related to whole-canopy photosynthesis, growth, and (ultimately) yield (Kirschbaum, 2011)." page 2 emphasis mine
From the Discussion:
"Cannabis Inflorescence Yield IsProportional to Light Intensity
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 ). These results were generally consistent with the trends of other studies reporting linear cannabis yield responses to LI (Vanhove et al., 2011; Potter and Duncombe, 2012; Eaves et al., 2020), although there is considerable variability in both relative and absolute yield responses to LI in these prior works. The present study covered a broader range of LI, and with much higher granularity, compared with other similar studies." page 9 emphasis mine
A second item of interest, which I did not find until I re-read the paper last week, is in the Results section:
"No CB effects were found in any leaf photosynthesis, leaf morphology, and post-harvest parameters; therefore, CB1 and CB2 data were pooled for the development of all models except secondary metabolites, which were only measured in CB1." page 7
CB = "culture basin"
In the experiment, the plants in one CB was topped, the plants in other were not topped. Based on the sentence I've quoted, the researchers appear to be stating that there was no difference in outcome between the plants that were topped and the plants that were not topped. That's the only time I have seen topping vs not topping addressed by researchers.
So basically what @Delps8 is saying is you can and probably should go higher with your DLI if everything else is dialed in. The biggest issue is the people responsible for the meter being used recommend 45 for a reason that doesn’t really make much sense.
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browntrout1
420 Member
I'm running 525 ppfd @ 24 hours..may increase it to 550
Delps8
Well-Known Member
I've shied away from 85°. One reason being a comment that Mitch Westmoreland made in his video on hemp. He stated that THC levels dropped signifcantly when temps rose above 78°. I don't have a quote on that but he's only got one video on YT, that I'm aware of.
Bugbee and Shane at Migro released this video a few weeks ago. My notes are below.
"7:00-we can get 60 mols/m2/day but you're going to average only 50 mols. By August, it's 45 mols and 35 mols by the end.
12:20-Bugbee has gone to 100 mols and yield is still going up.
Economic optimum - 30-60 mols
46:00-what should I be looking for in a spectrum?
SIgnificant priority on electric efficiency. Red is highly efficient. Bugbee recommends red + 10-20% white
At least 15% far red
Go to 20:00
Give your cannabis plants 1000µmol from the start.
Good to put some of your light in from the bottom. It's not a magic bullet.
Cool off at the end but it varies with genetics. For example 30° down to 20° at the end. For yield and for quality, it's very beneficial to have lower temperatures at the end."
Check out the temperature discussion starting at 56:00. I found it…enlightening.
Good video, I follow the logic on it. Was a bit open ended in terms of start warm end cool. Do you know at what point it’s recommended to initiate the downward temps? Based on what he was saying I’m assuming depending on your strain it’s probably somewhere in the week 4-6 range since a lot of it’s about preserving the flowers.
I didn't watch the video, and to be honest the acronyms are a foreign language, but for the short time I've been growing I have noticed denser and heavier buds at cooler temps, and more airy and lighter buds at higher temps, that's why I try to run my flower tent at 72F during lights on, and as low as 65-66F at lights out, keeping humidity much lower at end of cycle, like 30-35%, with a good fan blowing on them to prevent PM and bud rot...just my 2 cents, like I said only been growing since '08 but I've learned a lot in that time, and it works for me
Delps8
Well-Known Member
Yup, he's pretty vague on that point. It wouldn't surprise me if this was, partially, a teaser for a paper that's coming out.
For some reason, I'm thinking it could be the last two weeks so that would be starting at week 7 but I can't put my finger on it as to where I got that two week figure. I would really like to know since I'm looking at a harvest in about 40 days.
Welcome Bill. Great garden you're tending. Your handle @browntrout1 caught my eye, I miss not having a brown trout river/stream nearby, you must be a fly fisherman. Sorry I can't help with your question but the members above are great and have lots of experience. Good luck and tight lines.
Delps8
Well-Known Member
Yeh, '08's a newbie. ;-)I didn't watch the video, and to be honest the acronyms are a foreign language, but for the short time I've been growing I have noticed denser and heavier buds at cooler temps, and more airy and lighter buds at higher temps, that's why I try to run my flower tent at 72F during lights on, and as low as 65-66F at lights out, keeping humidity much lower at end of cycle, like 30-35%, with a good fan blowing on them to prevent PM and bud rot...just my 2 cents, like I said only been growing since '08 but I've learned a lot in that time, and it works for me
30° - wow. That's…south Arizona? I do get it about RH and bud rot. I think I just dodged a bullet on that in my current grow.
Gotta say, one of the advantages of autos is that you can run them for 20/4 or whatever and that will tend to help stave off bud rot. I lost a really nice looking photo plant a year ago to bud rot. On the other hand, my autos were "back up the truck" size grows and no issues at all with bud rot or PM.
I have seen comments about high temp and fluffy buds. Have you seen this across different strains?
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browntrout1
420 Member
Yes great trout fishing on the east coast...specs,brown and rainbows..
I see it more in hybrids, but there are Indica hybrids with genetics that were born of dank damp jungles, that are the exception, most Sativas actually prefer it warmer, so are more likely not to mold or rot, just from what I've seen, but I don't grow too big or too much at once
well I had 3 tents, which is what I considered "big" if I got 2.5 - 3 lbs per scrog 
I was doing good 
and to be quite honest I've never had anything worse than PM, never seen bud rot, but I've always had the means to control the environment in the grow room 
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I see you have been well taken care of.
What strain are you growing?
Here's some helpful info: Welcome New Members - Please Read Before Posting
Here is some information if you would like to start a grow journal How to Make a Grow Journal
If you want to see want other growers are doing, here's that link.
This is where you place your grow journal.
Journals in Progress: Current and Ongoing
And, after you have over 50 posts you can vote and enter our contests to win free grow stuff from our sponsors.
420 Contests: Win Cool 420 Prizes
Stay safe, and grow well my friend,
Tok..
Wastei
Well-Known Member
You lower temps at the end of flower to be able to lower humidity while still letting the plant transpire. It's to prevent mold and bud rot. When to start depends on flower density more than anything else.
Higher temps and humidity means faster growth rates and lower temps and humidity will slow them down. You do it as needed but you ultimately want to keep RH as high as possible without causing mold for better growth rates and potency. There's always a positive to negative return.
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