Do they have foxtailing by any chance?
65 DLI and lighting schedules
- Thread starter RastaDaddy
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You got any work to share with us?Would you be able to post your beauties? Let us AFN members try to remedy them!
I culled my plants some time ago and took down my tent... No photos of them for security reasons. However, I'll return after the grow room is set up. I'm just trying to get my finances in order. It is definitely happening, I think about posting my stuff in a new forum post and will definitely quote you, Frank, when I have it up.
I want to try Antonio's and Sawney's strains.
Both excellent sources of genetics…
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If power generation requirements are critical in your situation, why not grow autos? You mentioned wanting monster yields. Perhaps, check out @420autoflower ’s grows. If nothing else, you’ll enjoy seeing his work!
"Bleached buds", as an expression, is a carry over from HPS days. With LED's, some grows will result in buds that have white tops. Bubgee has looked into it and, IIRC, it was Fall of 2025 that he said that the cause was a high amount of 660nm light on flowers which impacted the buds before they bloomed. Earlier there was discussion that it was a high percentage of 660 but Bugbee ran it down to a high amount of 660.
Re higher PPFD's requiring high EC - I haven't anything like that in "the research" but I'd appreciate a link. I routinely grow at 1000-1100 in ambient CO2 and have never had an EC higher than 1.6. Nutrient demand is very hard to standardize because environments vary tremendously and the EC range the comprises the "sufficiency" level is quite wide (an EC of 1 perhaps).
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Interesting thread- I’ve just seen the effects of high DLI firsthand. My plants stretched up really high and then when I checked the DLI it was at 65 and the plants were struggling with that high DLI. You could see the light stress in them, the extreme uptake of calmag also occurred. This is documented in several books. I dropped the dli down by turning the lighting levels to 50% to get it into the 35-45 range across the tops which are not leveled.
I was keeping it at 40-45 until after flowering and then turned it up to 55 with CO2 running but had to adjust to the plants needs. The thing it once the damage is done those older leafs will not change and it’s the new sugar leaf I want to see signs of recovery in to determine success.
I was keeping it at 40-45 until after flowering and then turned it up to 55 with CO2 running but had to adjust to the plants needs. The thing it once the damage is done those older leafs will not change and it’s the new sugar leaf I want to see signs of recovery in to determine success.
I'm sorry to see what's happened to your plants but it appears that they've recovered quite well. That's extensive damage and it indicates that the plants were given far more light than the environment was able to support and they were exposed for a length period. It takes a lot of exposure to cause necrosis due to excess light.
Plants don't respond to "DLI". I realize that's DLI is used as shorthand here on AFN but DLI is the amount of light that a plant gets over the course of 24 hours. A DLI of 43 is both 1500µmol for 11 hours and 500µmol for 24 hours so I can't be used to manage plants. DLI does have a use but can't be used to manage plants because doesn't indicate how much light is falling on a plant at a given time. And that's what a counts.
Plants respond immediately to changes in light levels because photosynthesis is a continuous process. When a plant gets more light than it can handle, it will change internally (a bit) and, if there's still too much light, the plant will curl the edges ("canoeing" or "tacoing"). That will happen in about 30 minutes or so. When the light levels return to an acceptable level, the edges will uncurl.
If a plant is given an amount of light that it can process, say 1kµmol, it will continue to process that amount of light 24 hours a day until the plant is harvested or until the environment changes such that it can't support the plant in processing that much light. I've seen growers talk about plants needing "rest" or needing darkness but there's no metabolic processes in cannabis that require darkness. It really is just like the energizer bunny (fire it up and it will just go and go and go) and they do this because plants don't get tired. Plants do not tire because they don't have muscles that fatigue. They are "rate limited" by their biochemical processes.
On the other hand, if the environment has a limiting condition, such as heat build up in the grow area or inadequate water, etc. etc. the environment will not be able to support the plant and the plant will exhibit signs of stress. Other than that, cannabis will thrive at ~1000µmol, in ambient CO2, for 24 hours a day.
In years past, I've grown my autoflowers at 70-80 DLI and the only reason I reduced PPFD was, as I put in my grow journal at the time, that there was so much weed there just wasn't any reason to keep my light levels up that high. I was probably at 900µmol and 20/4 or 21/3 at the time.
In a stable, non-limiting environment, cannabis will thrive at 1000µol of light in ambient CO2. This is simply how cannabis functions. David Hawley, head of research at Fluence, found that cannabis shows changes in the shapes of flowers once PPFD > 1200. I've seen fox tailing at ~1100 so I've cut back to <=1050± in ambient.
In hydro, cannabis can be ramped to 1k very quickly (by day 21).
The data below are from my current grow. You'll note that PPFD values are the same from day 6 to day 16 because I f'd up moving the Rapid Rooters from the seedling tray into the reservoir. Once the roots got established in the reservoir, I was able to give the plant 550µmol of light on day 17 and ramp to 1000 on day 20.
Ramp rate is important because autoflowers have only about 28 days to fill out the canopy so a rapid ramp of PPFD is important to creating a big canopy.
In this grow, I'm growing a photoperiod plant but I've used a fast ramp for my autos. Prior to my most recent two grows, I wasn't able to get my plants to 1k until about day 35. I came to learn that the reason for that was that I wan't giving my plants a sufficient amount of nutrients. As a result of giving my plants the right levels of nutrients, they're able to get to 1k and stay that those levels.
One of the reasons for the fast ramp is that I grow in hydro and I do not believe that soil can ramp as quickly as hydro but soil can support high levels of PPFD. Hydro is a race car, soil is a locomotive—they can both get to 1000µmol but soil takes longer.
All of my grows are run at at least 1000µmol and there's no magic to that. Cannabis is a high light plant, in the same category as corn and sugar cane. Per the attached paper, the researchers were able to run cannabis at 1800µmol in ambient CO2.
As it's been made clear to me "650µmol of light is plenty of light for an autoflower plant" and I agree completely. If a grower wants to grow at 650 or 250, it's none of my concern.
What is also clear is that cannabis, as a plant, is able to thrive at light of 1000µmol of light, 24 hours a day, in ambient CO2. This has been known for years and is not a topic of contention outside of cannabis sites.
Why grow at higher light levels? Because crop size, crop quality, and bud quality rise as light levels rise. Cannabis is considered a "1:1" plant because the yield increases in, pretty much, a linear manner.
I've attached a marked up copy of what I refer to as the "Frontiers" paper which gave plants up to 1800µmol of light in ambient CO2. It's an interesting read, for a number of reasons if anyone's interested in discussing them.
I'm sorry to see that your plant had problems at whatever PPFD you were giving your plant but one of the amazing things about cannabis is that it will grow in a huge range of PPFD values and still deliver a decent crop.
Note - I've started running CO2 for this grow and things happen pretty quickly at 1200 and 1200!
