Trimming Fan Leaves? A question for plant nerds...

[ShutUpDonny]

Hey all,

I've been reading a bit about training, scrogging, etc, trying to prepare for the veg cycle I'm about to start. In those articles many people recommend that, in order for a proper yield, you should trim many of the fan leaves to allow light to reach bud sites. At first blush this made sense to me, but as I was just sitting here planning my scrog a question occurred to me.
Basically leaves are where the stomata are, and where the bulk of the chlorophyll is, right? They are where most of the photosynthesis takes place, in other words, and so they're most responsible for plant growth. If that's true then why would it matter if more light gets to the buds, especially if it meant cutting off leaves to get it there?
I know that buds are green from chlorophyll, so they must add a bit of energy to the mix, too (at least until they get covered in trichomes). But I also know that on most plants, the flowers are only for reproduction and basically just consume energy instead of creating it. Is this truly a totally different story with mj?
I'll spare you all my usual "I know nothing" spiel since it should be overwhelmingly obvious by now. But does anyone know the reasoning behind the above technique? Thank you for any help you can provide for the random questions of an addled brain.

>D

 

[OctoberDee]

You're gonna have lots of fan leaves before you get to the flowering stage (under most circumstances). Unless you're going for a certain training technique that requires removing the fan leaves your best bet is to leave as many of them on the plant as possible while in vegetative stage. Most times the plant will shed unnecessary leaves on it's own. By the time you get to flowering you may lose a lot of leaves. If not then you would want to trim the fan leaves that are covering bud sites and also this will direct more of the plants energy to creating flowers rather than using the fan leaves for photosynthesis. By nature a marijuana plant in flowering stage is a dying plant whose only concern would be to reproduce. Assuming you are not going to regrow the plant it would be ok to remove most fan leaves but you'd only want to do that a week or two before the plant is to be cut and cured. In a SCROG sitch you'd wanna trim the leaves under your screen because those leaves don't really get light in the flowering stage and are not necessary as they get no light and just die and fall off anyways. Hope that helps.
:bong-hits:

 

[ShutUpDonny]

Thanks Dee, that does help! I will be doing a scrog, and it totally makes sense that the leaves under the canopy are pointless and should be removed (I do have a bunch of CFLs that I can throw under the canopy when it gets to that point, but I guess that's a different subject...). And I get what you're saying about plants already "dying" even several weeks before you cut them - that's a really good point and a great insight. I think it will help with how I picture the life cycle of mj going forward. But it also seems in line with what I was questioning about getting light to the buds.

So I guess to distill my question down even further: Do buds really benefit more from chopping leaves in order to get the buds direct light, like most people recommend? Or would they actually grow more from getting light to as many leaves as possible, which makes more sense to my ignorant ass? And is there any research anywhere to fall back on?

Again, I'm not saying that the rule of thumb is wrong - I'm just trying to figure out what makes it right. And hell, maybe it's supposed to be used in much more specific situations than I'm assuming. I just want to understand :icon_dizzy:!

 

[OctoberDee]

The short answer is yes it benefits your buds to soak as much light up as possible.
Here's a snippet of info from a book you should buy called Cannabis Botany from R.C. Clark. But to get to the point:

Leafing is one of the most misunderstood techniques of drug Cannabiscultivation. In the mind of the cultivator, several reasons exist for removing leaves. Many feel that large shade leaves draw energy from the flowering plant, and therefore the flowering clusters will be smaller. It is felt that by removing the leaves, surplus energy will be available, and large floral clusters will be formed. Also, some feel that inhibitors of flowering, synthesized in the leaves during the long noninductive days of summer, may be stored in the older leaves that were formed during the noninductive photoperiod. Possibly, if these inhibitor-laden leaves are removed, the plant will proceed to flower, and maturation will be accelerated. Large leaves shade the inner portions of the plant, and small atrophied floral clusters may begin to develop if they receive more light.

In actuality, few if any of the theories behind leafing give any indication of validity. Indeed, leafing possibly serves to defeat its original purpose. Large leaves have a definite function in the growth and development of Cannabis. Large leaves serve as photosynthetic factories for the production of sugars and other necessary growth sub stances. They also create shade, but at the same time they are collecting valuable solar energy and producing foods that will be used during the floral development of the plant. Premature removal of leaves may cause stunting, because the potential for photosynthesis is reduced. As these leaves age and lose their ability to carry on photo synthesis they turn chlorotie (yellow) and fall to the ground. In humid areas care is taken to remove the yellow or brown leaves, because they might invite attack by fungus. During chlorosis the plant breaks down substances, such as chlorophylls, and translocates the molecular components to a new growing part of the plant, such as the flowers. Most Cannabis plants begin to lose their larger leaves when they enter the flowering stage, and this trend continues until senescence. It is more efficient for the plant to reuse the energy and various molecular components of existing chlorophyll than to synthesize new chlorophyll at the time of flowering. During flowering this energy is needed to form floral clusters and ripen seeds.

Removing large amounts of leaves may interfere with the metabolic balance of the plant. If this metabolic change occurs too late in the season it could interfere with floral development and delay maturation. If any floral inhibitors are removed, the intended effect of accelerating flowering will probably be counteracted by metabolic upset in the plant. Removal of shade leaves does facilitate more light reaching the center of the plant, but if there is not enough food energy produced in the leaves, the small internal floral clusters will probably not grow any larger. Leaf removal may also cause sex reversal resulting from a metabolic change.

If leaves must be removed, the petiole is cut so that at least an inch remains attached to the stalk. Weaknesses in the limb axis at the node result if the leaves are pulled off at the abscission layer while they are still green. Care is taken to see that the shriveling petiole does not invite fungus attack.

It should be remembered that, regardless of strain or environmental conditions, the plant strives to reproduce, and reproduction is favored by early maturation. This produces a situation where plants are trying to mature and reproduce as fast as possible. Although the purpose of leafing is to speed maturation, disturbing the natural progressive growth of a plant probably interferes with its rapid development.

Cannabis grows largest when provided with plentiful nutrients, sunlight, and water and left alone to grow and mature naturally. It must be remembered that any alteration of the natural life cycle of Cannabis will affect productivity. Imaginative combinations and adaptations of propagation techniques exist, based on specific situations of cultivation. Logical choices are made to direct the natural growth cycle of Cannabis to favor the timely maturation of those products sought by the cultivator, without sacrificing seed or clone production.

 

[convex]

I try and tuck leaves down and around budsites in early flower rather than cut.

As the grow progresses there will be obvious leaves that need pruning, but try and keep it to a minimum.

Cheers

 

[Onespark]

I think of the leaves as elevators that carry nutrients up and machines for photosynthesis. I usually pull the inner and lower leaves off in a SCROG and leave the outer leaves. Seems to not stress the plant and allow light into the lower depths. That with some LST works very well. Too much trimming causes a release of the wrong hormones for flowering. I have read Cannabis Botany but didn't remember that exact part...good stuff! What do you guys think about pulling those inner leaves? Seems to work out as long as you don't pull more than 20% of the plant off while doing it. The only other leaf I remove is something that becomes damaged and starts to reach the 50% healthy/damaged point.

 

[ttystikk]

I remember Seamaiden saying something about how removing healthy leaves to help the plant grow is kinda like fucking for virginity or fighting for peace... cracked me up!

Seriously, the plant knows what its doing. when leaves start yelloweing and dying in the understory of the plant, the nutrients in them are being transported elsewhere to help with further development. Think of fan leaves as not only the engine of plant growth, but also to a great extent its battery supply.

 

[BudPatch]

I'm like Convex, I like to tuck the leaves rather than trim them. Trimming any vegetation off the plant produces a hormone that can hinder your flower growth. It is good to let the buds get light, but the leaves are the power factories for your plant, if you remove them, it has less stored energy and less ability to make new energy for flowers. Hope that helps.

BP