To Defoliate Or Not To Defoliate

[DrPhoton]

alltatup

"This seems to contradict the stance against defoliation if light does indeed affect flower development."

The developmental differences are associated with the source to sink movement. The flower itself does not cause morphological change, the leaves around it do through photosynthesis.

[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.

[DrPhoton]

Im sorry, i was using terms from my human anatomy field. Although botanists seem to use it as well. Proximal and distal describe locations compared to a reference point. Proximal meaning the top of the plant, distal meaning the bottom.

[alltatup]

Dan, I don't understand this: "flower or fruit developement is more extensive in the proximal location of the plant. There are a few reasons for this, light is just one." This seems to contradict the stance against defoliation if light does indeed affect flower development.

What is "proximal location" of the plant?

Vitreous Fascinating about THC percentages!!

[DrPhoton]

A great question but one which is partly already answered with the original post. First i have the utmost respect for nebula, i take nothing from her and i believe she provides fantastic learning material. Her expereince is nothing to take for granted of.

"Cannabis is wind-pollinated, so it doesn't fatten any buds except the ones that have access to wind. Defoliation exposes the more of the buds to a breeze. Cannabis buds seem to get fatter when they're exposed to strong, direct light and defoliation exposes the buds to light."

The section on floral morphology is practically dedicated to this. There is no morphological properties of flowers in response to light or mechanical sensations, such as air movement.

"It's possible the plant focuses on bud sites during the initial part of flowering because it simply doesn't have leaves to put energy into"

I also address this in Leaf Photosynthesis, but i will elaborate on this. In the early stages of leaf development, leaves act like sinks. In just a few days, leaves begin the sink to source transition where they start supporting themselves and begin exporting photosynthetic resources, as a source. Its at this point and for the remainder of its life until senescence that it stays as a source. Removing leaves does not provide more photosynthate for flowers, as leaves are providing energy, not requiring it. They are sources.

As to the development of the bud structure, exposing light down the canopy further would allow a more uniform developed flower. It has typically been observed that flower or fruit developement is more extensive in the proximal location of the plant. There are a few reasons for this, light is just one. I completely support the idea for providing a structure that enables a plant to do this, as this creates a higher quality product. But removal of leaves to expose light will only do just that, create a more uniform flower structure. The yeild will not improve because all you have done is shifted where photons will land. There is no improvement in photosynthetic efficiency or efficacy, the total photosynthetic yeild is the same.

I may add some of this to the main article but i have to be careful at this point not to overdo and already overdone writeup. But really great question, any more questions are welcome.

[D.A.A.S.69]

Just thought I would throw this out here, don't know if it's right or wrong, but I'm gonna continue to take all the leaves an branches that's blocking light.It works for me.

[Bigpapa]

Vitreous, what strain are you getting 23% out of?

[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.

[Vitreous]

alltatup, I too defoliate in the same fashion as Nebula, been using this technique for quite some time. In the beginning I had learned that I was removing to little not making much of a difference. Now today it almost appears I may be too aggressive removing leaves. But NO. I think I have gotten closer to the max defoliation point, creating some of the largest colas I have ever produced. Regardless of the strain, I keep on doing the same thing to each individual plant. Here is what I get out of defoliating...
I noticed when I defoliated very little, the lower bud formations would cure a low grade THC, between 10-15%.
Aggressive defoliation would create percentages that compete in strength with the upper flowers. To a point where I could mix the lower cured buds with the upper and top section cured buds, and could not spot the difference, other than size. I then proceeded to have 3 THC testing done Lower, Mid and top..believe this or not, all 3 tests were 23% with a +/- of .03.
In the real world this would be considered impressive.
What Dan needs to know is basically, if you let the sun shine through, there is a benefit from top to bottom.

[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

[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.

[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... ????

[Dutchman1]

Ok, thanks for that and for the info.

[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.

[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