Yes @Calix that’s a great example
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There are three things that cause excess leafs
High N
High humidity
And high defol
Depending on what stage the plant is at , will depend on the outcome ie how it copes
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Now that’s how it’s done! Those green, chlorophyll rich leaves are gonna produce/support some fine bud.
I ruffled thru my Deep Chunk yesterday. The leaves upon leaves is just crazy! I picked out a bunch of dead and moldy spent leaves at the soil level and gave the plant a soil drench of a copper fungicide just to be on the safe side.
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I was convinced that defoliation was a trigger for larger yield and more potent buds, then I did a side by side test and the totals were nearly equal. So I stopped defoliating because I saw it as busy work, now this article has me thinking that some pruning could be helpful to the plant.
Sources vs. Sinks
First of all, you will need to understand the concept of Source vs. Sink within a plant. Pretty self explanatory, a source is any part of the plant that generates more photosynthate (sugar) than it requires for growth, and a sink is any part of the plant that requires more photosynthate than it can produce (or is producing). What is key to understand with this is that a plant tissue can change from sink, to source, and back to sink all as part of the plants natural process. For example, a newly forming leaf (fan leaf or bud leaf) is always going to be a sink, requiring more sugar to grow than it is currently producing from photosynthesis. . . but once that leaf has reached close to its mature size, it is producing much more sugar than it requires because it is hardly growing at that point. . . .and then again as that leaf becomes older and cells start to get older, the chlorophyll will actually lose effeciency and although the leaf may still look green and healthy, it is no longer generating more photosynthate than it requires to stay alive, and therefore older leaves become sinks again!
There are also parts of the plant which will almost always be sinks. Those are things like the roots (obviously no way of producing photosynthate, but still require it), the flowers on most plants because most flowers contain very little to no chlorophyll compared to a leaf, and seeds are always going to be sinks (the strongest sink).
The important reason I am explaining the Source vs. Sink relationship is because when you have too many sinks and not enough sources, your yield goes down and the overall vigor of your plant is reduced. So to maximize yield and sugar content in the final product (the buds), growers should try to eliminate other sinks as much as possible, while maintaining as many strong sources as they can without risking poor airflow or reduced efficiency with too much shading.
Keeping all this in mind, you can guess that a leaf which is receiving less light (heavily shaded) is most likely going to be functioning as a sink in the plant, drawing sugar away from other sinks that you may be more concerned about such as the buds. Removing leaves above the shaded leaf may give it more light, and maybe enough to start generating more sugar than it needs, but the lower down the leaf, the sooner it will be past its highest efficiency and the closer it is to becoming a sink permanently because of photosynthetic efficiency loss. Therefore, I tend to remove older fan leaves (less efficient) first before I go removing mature newer leaves higher up on the stems because they are more efficient.
Now, once you have removed any leaves that are past their prime, you may still have some fan leaves shading other bud sites, which in cannabis do produce their own smaller bud leaves. The larger fan leaves are MUCH more efficient at producing photosynthate than the smaller bud leaves, and because they tend to be more exposed to air flow they will also transpire more, meaning they help more water and nutrients move through the plant compared to bud leaves which have much less surface area and transpire/photosynthesize much less. So, that means it is better to keep large fan leaves, even if they are shading a bud site or two, because they will function as a source for the bud site (sink) and send its excess sugar to the bud. If you remove the fan leaf, the bud is already functioning as a sink, and so will have to get the rest of the sugar it needs from a different fan leaf on the plant (different source required), meaning a different sink is now getting less than it was because it is sharing its sugar supply from its own fan leaf. . . . this kind of sharing and relocating of sugar pathways takes extra energy in itself, and is not beneficial even if the bud site is no longer being shaded and can produce slightly more sugar on its own from the small bud leaves.
In conclusion, remove old fan leaves especially if they are no longer receiving any direct light. Try to maintain as many sources on the plant as possible by getting as much light and air flow to the newer mature fan leaves as possible. Remove any very low sinks that are far away from any strong sources because they will generate almost no photosynthate on their own, along with drawing photosynthate away from other sinks that are more local to the source leaves higher on the plant. And don’t worry if your bud leaves are shaded, because they are sinks anyways, so the plant is pumping all the excess sugar from local fan leaves to the nearest/strongest sinks it can find (your buds)!!
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Link please?
With that line of reasoning other plant units such as roots would never get any resources.
I’ll reiterate, sugars produced by any unit that has chlorophyll and is doing its photosynthetic thingie is not localized. The resources being produced are conducted, distributed, top to bottom via the pholem.
I don’t remove healthy leaves whether it be a peach tree or cannabis. Yellowing leaves while flowering? Correct the problem with a high N food. | Page 5 | International Cannagraphic Magazine Forums
Uncle Ben
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You forgot the CO2 flag, which is an indicator to the plant that the leaf is no longer a producer. If the leaf is processing CO2, the leaf is retained.
Another fallacy, leaf no good - the leaf contains nutrients which will be extracted and used by the plant as the leaf goes thru a state of impending necrosis. You remove the leaf, which is a storage unit, and you’ve deprived the plant of certain resources.
Took this pic yesterday. I’ll give this pure indica another week or two.
Uncle Ben
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ICMag discussion:
My post - Again, you guys are not getting it. The carbos produced are NOT localized. They are transferred throughout the plant top to bottom via the phloem. The phloem is the tissue that is responsible for the distribution of products made during photosynthesis.
The reason why you have “larf” at the bottom is based on a hormonal response called apical dominance. Auxins tend to collect and drive tissue production at the top of the plant. They will tend to get resources first.
Apical dominance means that the growing apex of a plant controls the quiescence of buds sitting in lower positions along a shoot. This kind of bud inhibition is termed ‘correlative inhibition’. Correlative inhibition usually has a gradient: the lower on the shoot, the stronger the inhibition.
Apical Dominance - an overview | ScienceDirect Topics
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Knock it off Tio,
Somebody might learn something………
Never mind, you are on a cannabis forum, if it isn’t bro science it’s not real!
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Great explanation, thanks for sharing… 
Great explanation, thanks for sharing… !
He’s telling you what you want to hear? 
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Right, it makes sense to me, I think I will not be the only one with this opinion, I respect yours but to each his own … 
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I always go with if I’m doing organic living soil -no defoliation, but in hydro or drain to waste it’s always getting nutrients where as in organic it stores it in the fan leaves. Just my 2 cents. 
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thanks for this, nice post 
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This one was crazy pheno barely any leaves and skinny skinny not sure what happened with it was next to supposed same strain and so different. I love it but it was a long flower so weather was the deciding factor
But I do understand defoliation but I’m also lazy this one I didn’t even try to trim at harvest I gave it to a friend larfey pos gorilla zKittes. Also I wasn’t trying to start an argument y’all are my people
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Does it look like it’s ready for harvest? I been trying to grow this for 3 years and can’t get it to finish in time. 2 years ago one pheno took forever to bloom and when it did look like big dandelions when they are white cotton balls . 10 foot tall and only 3.5 weeks of flower before the unforgiving weather forced harvest I couldn’t believe it was so developed in such short time and was very nice and sticky. I’ve heard about some pheno will have this trait for some reason idk but would like to look into why that happens . I mean super vigorous huge cotton balls with long hais like size of golf balls in bloom then two weeks later was fulley developed just not swollen ripe but still a awesome plant . Sorry for the long post but I don’t have any friends 
and nobody likes it when I get going on the subject.
Love all my OG family members y’all are the best
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Had the same problem with Dalat Vietnamese. Took forever to even show a flowering response but when it did, it exploded.
Is that pic now? If you’re in the states you have plenty of time to finish it. Try to retain all the leaves you can or you’ll never finish it.
Looks good!
Uncle Ben
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September 2022 .I got the genetics from my sister, she went on vacation to Costa Rica and purchased a bag of flower and she gave it to me when she got home. . Idk what to think about it but I will keep trying to grow it. I think my problem is just starting the seeds inside and transplanting it outside before it’s ready or maybe the climate is wrong for the plant and needs more growing time cause I literally harvest after the snow fly’s and I can tell they still need another month or so .I’m scared to grow it inside and transplant it outside and it reveg or Hermie or sometimes both this year I’m going to try to figure out how to transition to outside with maybe different light cycles. I was told the middle of May is good time to start hardening them off but still only 14 hours of daylight so they get over 12 dark period this time of the year but some day I will make it my bitch and put her out to do her thing . I named her Cold Snap.
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Can’t tell for the pics, you need something that make macros for this kind of question. But considering the general shape, i share the feeling of Ben. Look like a “double-flo” strain.
For transition, i’ve never crushed my mind back in the day. Both for greenhouse or guerilla’s crops. Just full 24/0 until satisfying maturity, then transplant. My challenge of each year was to transplant the earliest possible, generally in March-April. But it was at 45°North.
" double flo" ? Now I’m all over this … What is double flo?