Reducing ppfd and dli in last coouple of weeks of ripening?

Just wondering if it's beneficial to reduce ppfd and dli incrementally during the last couple of weeks of flower? I have a nyc diesel up the back and an ethos cookies r2 up the front both are in 7th week of flower. The nyc will run for a fair bit longer the cookies is a nine week strain and she's getting close. Is it scientifically proven or just bro science?

Look to me like they could handle more.

Thanks, I haven't reduced the intensity or dli as of yet, cheers for the response

I followed this DLI chart last run in a 9 light flower room with multiple cultivars that I have ran repeatedly, the yield was very similar to running lights 100% power start to finish. Your power bill will be lower with less continuous wattage running and also HVAC wattage (if applicable). The Photone app on cell phones works very good. I compared it to an apogee i returned because of how good it worked.

I'm using the same dli chart atm and the one for my autoflowers also it's good to have a guide seems pretty spot on, I use the uni T btu lux meter and convert that to ppfd then calculate dli works well for me. I always wondered about the photone app and if it was accurate or not, good to know it is. Thanks for your reply. Here is 5 zkittles autos at week 4 following the autoflower dli chart.

There was some collage research that tried more light at the begining and lower light in the end and they got some good results.allsoo less light means less heat soo more terps survive

Less light at the end yes, helps with fox tails and white hairs.

That's the main reason for my question preserving terps, and avoiding foxtails thanks for your response

Plants just no need so much light at the end so safe your bill, too much light can cause stress and foxtailing, and you can lower your temp but do it last week before harvest not earlier

The only place I've seen recommend reducing light levels is at growlightmeter.com. When I tested Korona/Photone and corresponded with the programmer (2021), I asked him if they had any citations for the light levels that were recommended and he stated that they were on the bottom of each web page.

The reason I asked is that I can't find any literature re. decreasing light levels and, since light is the only way that plants generate food, which means the only way they can create energy, reducing light levels didn't make sense to me. I can't think of a living organism that benefits from having a reduced energy level.

In the three years since then, I still haven't found anything that supports the idea of reducing light levels. In contrast, research has shown that yields and crop quality (the ratio of flower to total above ground mass) increases in an almost linear manner to light levels. Those light levels were 1800µmol in one expirement and, per Bugbee and Westmoreland, yield increased even when they "ran out of light" at 2000µmol.

The recent video by Mitch Westmoreland that he posted on YouTube is a goldmine. It sums up a lot of the bits and pieces that I've found I wondering around the internet over the past few years. He posted it a few months ago and it's essentially a summary of the topics that he defended in his PhD dissertation. It's only 50± minutes and it substantiates a lot of the things that Bugbee has said, as well as topics that Bugbee has hinted at over the past three years.

Back to reducing light levels - if anyone has any research to show that reducing light levels improves yield, quality, or enhances secondary metabolites, I'd love to read it. Along with that would be why that happens because, as I wrote a few paras up, reducing light levels means that there's less glucose generated with means that plant metabolism slows.

The big reveal in his video is something that he mentioned in his video on hemp back in 2022(±)* and that Bugbee first hinted at the beginning of the year — run your temps up to 85°± in veg and early flower but drop temperatures into the 70's or high 60's as flower progresses. That's the best approach to preserving secondary metabolites. Now that I think of this, Shane @ Migro dropped a YTY vide on this in the past week or so and DeBacco will probably repeat it in the next few weeks so there's lot of outlets for the info.

In short, don't drop light levels but do drop temperature levels (starting in about the third week of flower - Shane's video makes is crystal clear, Westmoreland isn't specific on when to start dropping temp).



*That video is about "hemp" but that's just the appellation he was using at the time for cannabis that was low enough THC to fit under the then-limit for THC levels for research at federally-funded institutions.

The best growth come from high temps, high humidity, high light intensity
Upon flowering you are trying to balance growth with trichome preserve measures so you can't go too high on the heat or rh or even light because it generates again, heat..
The best weed I smoked was in the malana mountains in india, high light intensity, very low temps.
It's a basic recipe for success in weed grows, the more light the better.
Sure at some point plants take less light as they are finishing, they also take less water, but water we can see, light saturation within the plant at late stages and when it's starting to drop off is still debatable and probably varies with each set up or strain to try and judge and conclude beforehand.

Delps8 said:

The only place I've seen recommend reducing light levels is at growlightmeter.com. When I tested Korona/Photone and corresponded with the programmer (2021), I asked him if they had any citations for the light levels that were recommended and he stated that they were on the bottom of each web page.

The reason I asked is that I can't find any literature re. decreasing light levels and, since light is the only way that plants generate food, which means the only way they can create energy, reducing light levels didn't make sense to me. I can't think of a living organism that benefits from having a reduced energy level.

In the three years since then, I still haven't found anything that supports the idea of reducing light levels. In contrast, research has shown that yields and crop quality (the ratio of flower to total above ground mass) increases in an almost linear manner to light levels. Those light levels were 1800µmol in one expirement and, per Bugbee and Westmoreland, yield increased even when they "ran out of light" at 2000µmol.

The recent video by Mitch Westmoreland that he posted on YouTube is a goldmine. It sums up a lot of the bits and pieces that I've found I wondering around the internet over the past few years. He posted it a few months ago and it's essentially a summary of the topics that he defended in his PhD dissertation. It's only 50± minutes and it substantiates a lot of the things that Bugbee has said, as well as topics that Bugbee has hinted at over the past three years.

Back to reducing light levels - if anyone has any research to show that reducing light levels improves yield, quality, or enhances secondary metabolites, I'd love to read it. Along with that would be why that happens because, as I wrote a few paras up, reducing light levels means that there's less glucose generated with means that plant metabolism slows.

The big reveal in his video is something that he mentioned in his video on hemp back in 2022(±)* and that Bugbee first hinted at the beginning of the year — run your temps up to 85°± in veg and early flower but drop temperatures into the 70's or high 60's as flower progresses. That's the best approach to preserving secondary metabolites. Now that I think of this, Shane @ Migro dropped a YTY vide on this in the past week or so and DeBacco will probably repeat it in the next few weeks so there's lot of outlets for the info.

In short, don't drop light levels but do drop temperature levels (starting in about the third week of flower - Shane's video makes is crystal clear, Westmoreland isn't specific on when to start dropping temp).



*That video is about "hemp" but that's just the appellation he was using at the time for cannabis that was low enough THC to fit under the then-limit for THC levels for research at federally-funded institutions.

Click to expand...

Thanks, very informative I'll check it out