Defoliation, a scientific approach...

So is it an indoor grow? And which lights do you use? Is it a SOG type of grow?
Have you noticed any differences or done any side by side experiments yet?
Studies have indicated so far, that new growth may likely be directly influenced by the amount of irradiance which reaches the specific point of the plant. I have heard about the influence of air flow as well, but so far I couldn't find any papers on this topic.

indoor grow yes
lights hps
sog no

since you said removing any amount of leaves is defoliation
then i really cant remember that far back, it must be like 18-19 years since i have left a plant to grow and not removed a single leaf
over time i would say i remove less now than i did in the past due to unfavorible results, mostly with indicas
and finding other ways to open the plants up to a more evenly spreading footprint

as far as differences go its very pheno dependent , with the right pheno spacing and planning very little leaves should need to be removed imo
many types will suffer as a result, removing too many leaves will make the colas smaller
removing too many leaves from indica types can cause distorted regrowth and gaps in the colas with extra leaves that regrow
on the other hand i have seen plenty of sativa types respond ok to large amounts of leaf removal they still grow large colas with many plants fitting in a tight space

the airflow thing is more about avoiding mold/budroot and pm, when colas are close together the local humidity around them is high if the air is not freely moving around all the
colas and foliage, also when the plants are large and bushy with lots of leaves overlapping moisture/water gets trapped on the leaves
i mostly remove leaves and small thin branches from the bottom and blow air under the plants , which also gets sucked up through them by the extractor above

if you feel your plants need lots of leaves removed in order for them to grow healthy and give the max yield in the space
then it could equally be said that you could grow a different plant/pheno keep them smaller space/plan it better and virtually no leaves should need removing , each to their own

plants like these with huge fan leaves can be a problem but picking leaves off them will make them worse, and they look sexy so it should be a crime anyway,
better to bend them or tie them out to allow more light in
buds that grow under huge leaves like that do seem to suffer a little they seem pale green or almost white in some cases where they were shaded




peace

manti said:

I am new to this forum so maybe I am a little bit naive about that, but I hope the best. There must be people out there, who are interested in scientific exchange... ... I hope... :-/

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Very interesting and thought provoking info bro.Id suggest you visit the logical gardener if you want to chat with folks who place a high value on science in the garden.

When I look at a plant....let's say in late-veg....I take it out and look down at it from above. The leaf pattern is so amazingly precise in placement there's no doubt in my mind that this plant has its shit together and knows how many and where to put the leaves as it grows.

Go ahead.....you do the same and you'll come to the same conclusion.

It's my opinion (sorry I know you're looking for scientific facts) that such a smart plant also has the ability to discard any leaves that are not contributing to the plant. It feeds from the leaf and then it falls off.....all by design.

Again my opinion.....To think that we are smarter than our plants in regards to leaf placement and amount is a bit unrealistic.

testiclees said:

Very interesting and thought provoking info bro.Id suggest you visit the logical gardener if you want to chat with folks who place a high value on science in the garden.

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Well it wasn't me who said that it would be unlikely to create a thread which stays scientific. I was just trying to find some people which are interested to look into this topic a little bit deeper...

skunkd0c said:

indoor grow yes
lights hps
sog no

since you said removing any amount of leaves is defoliation
then i really cant remember that far back, it must be like 18-19 years since i have left a plant to grow and not removed a single leaf
over time i would say i remove less now than i did in the past due to unfavorible results, mostly with indicas
and finding other ways to open the plants up to a more evenly spreading footprint

as far as differences go its very pheno dependent , with the right pheno spacing and planning very little leaves should need to be removed imo
many types will suffer as a result, removing too many leaves will make the colas smaller
removing too many leaves from indica types can cause distorted regrowth and gaps in the colas with extra leaves that regrow
on the other hand i have seen plenty of sativa types respond ok to large amounts of leaf removal they still grow large colas with many plants fitting in a tight space

the airflow thing is more about avoiding mold/budroot and pm, when colas are close together the local humidity around them is high if the air is not freely moving around all the
colas and foliage, also when the plants are large and bushy with lots of leaves overlapping moisture/water gets trapped on the leaves
i mostly remove leaves and small thin branches from the bottom and blow air under the plants , which also gets sucked up through them by the extractor above

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Well that is interesting, and makes totally sense. If you already have a pheno fitting the environment, the results would be much less significant than when you alter the natural habitus of another pheno to fit them and in consequence clip the misplaced leafs in that process.
I have read, that the plants measure the significance of the individual budsites by light and airflow. This is because well lit sites which are exposed to airflow are most likely to be at the top of the plant and have a higher possibility of being pollinated through the stronger airflow. However I havn't peer reviewed this information yet. Additionally it should prevent mold as well, as you said this is one thing I totally forgot about.
What was the biggest amount of foliage you removed in one session so far? And which exact strains did you find to react positively/negatively to defoliation?

Edit: Nice photos by the way...

lilroach said:

When I look at a plant....let's say in late-veg....I take it out and look down at it from above. The leaf pattern is so amazingly precise in placement there's no doubt in my mind that this plant has its shit together and knows how many and where to put the leaves as it grows.

Go ahead.....you do the same and you'll come to the same conclusion.

It's my opinion (sorry I know you're looking for scientific facts) that such a smart plant also has the ability to discard any leaves that are not contributing to the plant. It feeds from the leaf and then it falls off.....all by design.

Again my opinion.....To think that we are smarter than our plants in regards to leaf placement and amount is a bit unrealistic.

Click to expand...

I agree with you mostly on the fact that the plant is able to organize itself when left alone. I think results would be more significant in plants with altered growth pattern like topped and trained plants. However it seems -at least from studies in other plants- that there might be some influences on plants without altered patterns as well. Would be interesting to get more into this details.

I personally like to defoliate. Once I flip to flower, I do all my lowers on the plant (normally around 1/4-1/3 of the plant depending on strain. After they stretch for a couple weeks I will go in and clean up the lowers one more time. At about week 3-4 of flower, I will start to remove a few of the larger fan leaves that are directly shading buds, and try to let a little more light in. Through out the grow as I notice large fan leaves that are directly shading buds or blocking a lot of light from getting in or overlapping fans, I will remove them. The last week, I will start to completely remove all the fans, a little bit each day until they are completely gone the day I harvest. I do this because it makes it easier when I harvest to separate the fans so when they dry and get trimmed, its all sugar leaf for extraction and the fans don't have to get separated from sugar while trimming. I also feel that opening up the plant by removing fans in the last week helps finish the plant off and finished the shaded buds in the middle better.

I have done an experiment where I did no defoliation on one side of the room and I did the other side how I explained above and I got 5oz more on the side I defoliated. It was a 6k room with the same cuts from the same mother on both sides of the room. I did this about 8 years ago so its been awhile. I get 2#+ per light regularly doing it this way.

Just my personal opinion and experience

This is a room that I defoliated like I described above. If you look closely there are not many fans left, if any at all.

manti said:

Well it wasn't me who said that it would be unlikely to create a thread which stays scientific. I was just trying to find some people which are interested to look into this topic a little bit deeper...

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i got you...and i still suggest @ The Logical Gardener you might strike up a worthwhile convo among sciece based gardeners.

I agree that defol theories merit discussions and experiment.

After embarking on my journey , its an obvious , depending on how you train your plant/s you are manipulating that plant and there for the cause and effect comes into play , on a normal growing plant outdoors you wont see big fans leaves stacking and a static light that sits in one position.

Topping...especially in veg.....will increase yield if done correctly....but topping is done more for bushiness and adding branches than attempting to maximizing growth from removing leaves.

lilroach said:

Topping...especially in veg.....will increase yield if done correctly....but topping is done more for bushiness and adding branches than attempting to maximizing growth from removing leaves.

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Yea I like to top as well. I top 3 days after transplant from cubes, then about every 7-10 days after that and I wait about a week from last topping before I flip to flower. Normally top 3 times indoors, sometimes more if I'm running multiple strains and some are getting too tall and I want the shorter ones to catch up

I want to participate in defoliation.

707humboldt said:

I personally like to defoliate. Once I flip to flower, I do all my lowers on the plant (normally around 1/4-1/3 of the plant depending on strain. After they stretch for a couple weeks I will go in and clean up the lowers one more time. At about week 3-4 of flower, I will start to remove a few of the larger fan leaves that are directly shading buds, and try to let a little more light in. Through out the grow as I notice large fan leaves that are directly shading buds or blocking a lot of light from getting in or overlapping fans, I will remove them. The last week, I will start to completely remove all the fans, a little bit each day until they are completely gone the day I harvest. I do this because it makes it easier when I harvest to separate the fans so when they dry and get trimmed, its all sugar leaf for extraction and the fans don't have to get separated from sugar while trimming. I also feel that opening up the plant by removing fans in the last week helps finish the plant off and finished the shaded buds in the middle better.

I have done an experiment where I did no defoliation on one side of the room and I did the other side how I explained above and I got 5oz more on the side I defoliated. It was a 6k room with the same cuts from the same mother on both sides of the room. I did this about 8 years ago so its been awhile. I get 2#+ per light regularly doing it this way.

Just my personal opinion and experience

This is a room that I defoliated like I described above. If you look closely there are not many fans left, if any at all.
View attachment 3425608

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What are your growth parameters? Is it indoor? Do you use SOG or something like that? And what strains have you experience with?
Do you have a journal of your side by side experiment? This would be very helpful I guess...

Sidenote: I tried defoliating some plants in the end of the 3nd week now, following exactly your approach. Let's see how this turns out...
Sadly I don't have a control group and those are plants from seed as I am in a selection phase for a new pheno for cloning. So at the moment everything here is quite crowded, and there is no room for a side by side experiment at my place. I am really looking forward to do this once I have enough room for at least 4 identical plants to experiment on, but it might take a while to get there. Until then it would be great to collect more background on the factors of interest.

testiclees said:

i got you...and i still suggest @ The Logical Gardener you might strike up a worthwhile convo among sciece based gardeners.

I agree that defol theories merit discussions and experiment.

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I am actually working with a guy from the local University but our problem is, that we can't work on this topic in the labs there or even publicly because we have a little legislation problem in our country. So doing chemical analysis is a little bit sneaky for us and setting up larger test crops under controlled environments are even unthinkable...
I thought it would be a good idea to involve the people actually working with this plants because I assumed a lot of experience and interest amongst them.

240sxing said:

After embarking on my journey , its an obvious , depending on how you train your plant/s you are manipulating that plant and there for the cause and effect comes into play , on a normal growing plant outdoors you wont see big fans leaves stacking and a static light that sits in one position.

Click to expand...

That's why I assumed that the results of defoliating might be more distinct in plants with altered growth pattern, but so far it is only a theory of mine...

lilroach said:

Topping...especially in veg.....will increase yield if done correctly....but topping is done more for bushiness and adding branches than attempting to maximizing growth from removing leaves.

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Don't get me wrong at this one. I meant that you alter the growth pattern of the plant, therefore limiting its self organizing abilities. That is the point where it might be beneficial to remove shading foliage which the plant produced while aiming for a normal growth pattern. So the one and the other might go well together. But as I said, this is only a hypothesis from me so far.

AlphaPhase said:

I want to participate in defoliation.

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Do you have some grow space to spare and would be willing to document a side by side experiment on some clones?

manti said:

What are your growth parameters? Is it indoor? Do you use SOG or something like that? And what strains have you experience with?
Do you have a journal of your side by side experiment? This would be very helpful I guess...

Sidenote: I tried defoliating some plants in the end of the 3nd week now, following exactly your approach. Let's see how this turns out...
Sadly I don't have a control group and those are plants from seed as I am in a selection phase for a new pheno for cloning. So at the moment everything here is quite crowded, and there is no room for a side by side experiment at my place. I am really looking forward to do this once I have enough room for at least 4 identical plants to experiment on, but it might take a while to get there. Until then it would be great to collect more background on the factors of interest.

Click to expand...

Indoors and outdoors, although I have never done a side by side outdoors I still do the same defoliation.

No I don't grow sog, I do 4-5 plants in 10g pots per 1000w light over a 4x4 area, and veg for 4 weeks.

No journal with a side by side, this was a while ago