To Defoliate Or Not To Defoliate

[DrPhoton]

Removed for security reasons.

[desertdan]

Great research and well written. I am an outdoor grower and from experience I will only prune for shape early in the season on some strains. I think the reason there are no good controlled experiments is because of the problems with cannabis not legal most places. I do very little experimenting because I need to keep number of plants at a minimum and try to grow sufficient smoke for a whole year. Keep up the great work. I enjoy reading well thought analysis.

[DrPhoton]

Yes i have followed your work since i was first a member here, i too grow outdoors and indoors. I like to at least top my outdoor plants once because i believe the main cola of a untopped plant acts more like a sink compared to the rest of the plant. Making the main cola larger while the rest of the plant is neglected.

[Camk]

Great read thank you helps me a lot on this subject!!

[9fingerleafs]

excellent article my friend... im glad someone is clearing the air about this whole hardcore defoliation trend going on

[abadtrip]

Awsome read I have an auto I didn't defol and I am going to leave it now.

thanks for putting the time in to provide us with this information

[Campesino]

So exposing more light to flower sites does not appear to offer any advantage to the flower development.

Hey DrPhoton I am not sure that the evidence that you provide justifies this conclusion. The fact that flowers do not photosynthesize enough to support the plant does not mean that they are not photosensitive. Plants invest more energy in flowers that are exposed to light. They cannot support themselves without leaves, but exposing flowers to light stimulates the growth of those flowers.

[DrPhoton]

Totally understand campesino, but again that would imply that flowers have photoreceptors. Which i argue they do not, at least to the extent of my reading and understanding of the discoveries of how plants have been studied over the last century. For example, taken from long memory. Phytochromes were only found in leaves as plants that were presented with light cues never responded unless the light was presented to leaves. Other parts of a plant such as stems and flowers never responded.

A quote from a quick search on the subject

Hans Mohr · 2012 · Science

"The characteristics of the flowers (including stamens, pistils, corolla and calyx) are hardly modified by light. A potato plant will form very similar flowers under all circumstances which allow flower formation at all."

[Campesino]

The sugar leaves may send important signals if not the flowers per se.

[DrPhoton]

Ohnestly, so could the larger fan leaves. The smaller "sugar leaves" are just younger leaves that develop between the calyx from the same branch as the surrounding larger fan leaves.

[DrPhoton]

Omitted with new information and improved readability. I would really recommended reading again if you have already done so. There has been some good information from people that i decided to add. I am much happier with it now and feel it contructs the message more clearly. There will likely only be minor improvements from here on out.

[alltatup]

I just read it twice and took notes from it; thanks a lot for all your effort! I had read Clarke on "leafing" before, and I am glad to find that particular passage again.

We watch lower buds mature all the time--buds that clearly aren't getting as much light as the upper buds. I understand why now.

Shade vs. Sun Leaves: Very useful information. Stress and sex change: ditto.

[DrPhoton]

Yes, although i make the comment about leaf transmittance, not all light makes it down. Eventually the light that passes through leaves gets absorbed, by the time you get to the bottom there is not much left. Removing branches that develop flowers is beneficial here as they will only create smaller larfy flowers. So instead that energy is directed to the main flower sites.

[DingusKhan]

Holy cow. What a great series of reads. Thank you, very thought provoking. I'm definitely going to try to go au naturel on one of my current grows. I might try to get 2 clones to go together in 1 bucket or bin.

[Dutchman1]

Great stuff. Thanks for your time and effort.

[Obi-Wan]

This is a great article, Thank you for taking the time to research and summarize the information. As a grower that practices controlled and selective leaf removal I have a few follow up questions for you regarding sections that left me somewhat confused as well as pondering what might be a greater reality.

As you close out your introduction you state:

“ There are various methods on how it is recommended to be performed, but typically it will involve the non selective removal of leaves of a varying amount at varying times”

Then under the section titled Air & Light on Leaf Photosynthesis, you state:

”The traditional method of defoliation is a non selective process that removes specific amounts of leaves at specific times. What is usually practiced and is learned through experience is how much is too much, when & how often such a process should be used during a plants life.”

So my confusion is centered around the idea of selective leaf removal. When specifying how many leaves, from what location,at what times, and how frequently. Did we not just create a specific process for selecting leaves for removal?

If so, is a good portion of the controversy surrounding the issue of defoliation simply a misrepresentation of terminology, with some using the text book definition of the word while others practice a more selective approach?

[DrPhoton]

Good question and i can see your confusion. The problem may be down to what i define the difference between selective and non selective. The selective and non selective terms i associate with location of removal. For example, using non selective herbicide does not differentiate between different weeds, so it is not subjected to a selective process.
I chose that wording to differentiate between defoliation for improved yield and defoliation where leaves are removed for improved health. Such as lollipopping or dead leaf removal etc.

Defoliation describes the process of removal or loss of leaves. It does not describe the methods or purposes it may be used for. That requires extended terminology wether that is current or new.

The other problem is that the different methods of defoliation out there, are based on different things. If one develops their method from their beleif on plant stress response. Then the matter of defoliation is a non selective process as the location of removal is irrelevant. However other methods may be selective.

It may be that i need to redefine the terms as they can mostly be viewed as selective processes as well.

What you think ?

[DrPhoton]

I have reconfigured the explanation for defoliation and omitted, changed and moved the second paragraph mentioning the process.

"There are various methods on how it is recommended to be performed, but typically it will involve the selective or non selective removal of leaves, of a varing amount at varying times during a plants grow. This is dependent on the method provided by the grower and their reasons or beleifs which define the process."

"Removal of lower or older leaves or braches, with less exposure to light, could impact a plants performance, however i would not consider this part of the typical use of defoliation for improved yield but the more practical form through pruning practices.
To some extent plants do this themselves, like how leaves are abscent inside a bushy tree. We do this also by methods such as lollipopping. However this is a proven method and is practiced throughout horticulture."

[Dutchman1]

OK OK, I want to hear what you feel is the best way to defoliate or not defoliate from what you have learned. You surely have an opinion at this point. I feel like your still skirting the issue even though you have provided a lot of information at this point. even though you did say that most of the defoliation done by people is incorrect ( in so many words) .

[DrPhoton]

I researched and published this information a while ago, i now have consolidated this data and worked on improving its presentation. While adding more recent data.

No one is doing the method wrong because there is no one definitive standard. There are many ways to do it based on ones beleif or experience. As such based on what i know about the science of defoliation, there is no best way because in my opinion the idea of defoliation to increase yield is wrong.

When i talk about removal of leaves underneath the plant, i am talking about a more traditional form of "pruning" rather than leaf removal. This is called thinning.

[Dutchman1]

Ok, thanks for that and for the info.

[Bigpapa]

Hey DangerDan. Great information. I take from this information that there is a consensus that the foliage serves a purpose. But I also take from all of this that some of the lower flower sites suffer somewhat from loss of light as a result. I’m wondering if anyone has ever done staged harvesting. I am a hobby grower who does one plant at a time. Right now I have a Northern Lights plant that is in her 5th week of flower and is covered with buds. All of the top buds are benefiting from the 600w HPS. However, the foliage is so dense that the numerous lower buds are suffering somewhat. I’m considering harvesting all of the upper buds and seeing if the lower buds can fatten up any. That would mean reintroducing nutrients AFTER an initial flush. Any thoughts along this line of thought?

4x4x80 tent ⛺️
600w MH/HPS
4” in-line exhaust fan
4” fresh air intake fan
3.5 gallon DWC
Regulated temp. and humidity
Using General Hydroponic Flora Trio
supplimented with CaliMagic and HydroGuard
on R/O
Nutrients changed every 7 days

[DrPhoton]

Yes exactly, indoor lights do not provide the same level of capacity compared to outdoor sunlight. For example, 600 watts HPS can produce roughly 700umols per square metre. Where as sunlight can provide upwards of 2000umols. You would need a sodium gas discharge of roughly 2000 watts per square metre to compare. With low wattage lighting, penetration is limited. So undergrowth is neglected. This is because source to sink priority is not equal. It is biased depending on several factors such as proximity, developement, translocation pathways.

If you harvest the healthy flowers and leave the underdeveloped, you can get added value from the leftovers. Care must be taken as the plant will undergo massive shock and could die. I have tried this before with success but it was not worth it because you leave very little plant material and waste a alot of energy in trying to recycle it. In the future it would be better to prune the lower canopy and force the plant to send this extra energy to more valueable sites rather than underdeveloped flowers.

[D.A.A.S.69]

Morning BigPapa, of course you can harvest in stages, take what's ready, an wait for the rest to get ready, I would just feed them molasses at the end.

[alltatup]

I went through Nebula's defoliation during flowering tutorial again (http://www.growweedeasy.com/nebula-f...ation-tutorial), and there's no denying the massive buds that she gets on her plants. Prior to switch to 12/12, at the time of lollypopping, Nebula's technique involves the removal of all large fan leaves, but she leaves on the plant "any small fan leaves as well as the top few pairs of big fan leaves of each cola completely untouched." She doesn't remove a single bud site--only leaves.

As we all know, with the switch to flower and the stretch, a healthy plant will pretty much completely releaf itself by the end of week 3 of flower. Nebula: "Usually by around week 3, a bunch of budlets have formed. At this point I remove all of the major fan leaves one last time. Make sure to especially take any big leaves with long stems.You're forcing the plant to focus on the buds during this crucial phase of their development."

She also makes the argument in this tutorial that colas don't develop all the way down if the plant isn't defoliated--that the main cola will be shorter without defoliation.

I'm curious to see that you think, Dan, of her statement that "You're forcing the plant to focus on the buds during this crucial phase of their development." Her results are undeniable, but it seems to me that a plant is inevitably going to be focused on bud development during flowering; that's its nature! But without defoliation, the colas don't go all the way down like hers do... ????

[DrPhoton]

I would love the idea, of the practice of defoliation to increase yields. Another technique for improved yields is always wanted. However i need more than empiricle data. Even if there is no sound science of the reason how it could possibly work, i would need at least some evidence of a control compared to a variable. So far, the few who have documented it show no improvements but instead inferior results in comparison.

Although i support the idea of providing more light to the lower canopy, this is just for quality rather than quantitiy reasons. Wether this is by removing a select few fan leaves, or by training the plant to allow more light to get through.

[Chefbjy]

Not saying it improves yield but I do think the control and the time frame you can easily fit more defoliated plants into one area rather than one trained plant that spreads across the whole area. So how do they calculate approximate yield from seeds and strains? Are they based off a process of defoliation or a plant they just let grow to it's full potential? If you could get at least half of what your plant should yield you could grow two more plants in the same space resulting in another half of the max you could get from one that will ultimately grow to fill the environment and only produce what has been recorded.

[DrPhoton]

Sorry i misunderstood you, this is getting a little off topic. However. I think you have the wrong end of the stick, so to speak. The number of plants does not dictate the final yield, the light source does. Ultimately you are always limited by the light source until plants become co2 limited. Adding more plants in a grow, reduces vegetation time. Although because of the structure due to shorter vegetation, you gain efficiency there as well. There is a point where adding more plants creates too much crowding and reduces canopy efficiency. Trying to cram more plants in through pruning practices isnt going to help much, if at all.

If you wish to talk more on the matter give me a pm.

[pjhelferich]

Thanks for all the info guys . I'm a new grower and i'm more confused then i was before . I'll read again and decide what way to go.thanks rick

[alltatup]

rick, Welcome to the forum! One thing all the articles say: this is not a technique for new growers to try. So you might want to wait on it. Everyone also stresses that it's only to be used on the healthiest and most vigorous growing plants.

[Dutchman1]

Agreed alltatup.

[DingusKhan]

Also, it helps to remember that you can do either, and if you don't overdo anything, it will work great. As new growers, we get over-eager to do stuff OR dead set against doing other things, when really the most important thing is to stay close to the norm and JUST FINISH your first grow. Once you get to the other side, you can do your next one differently, and see if you like it better.

If there are this many growers with this much difference in opinion, then they are probably both right. Do anything that some else has done (read some completed journals, I recommend Tika PDFs) and copy them. Next, copy someone else who does it differently.

You'll be fine.