Hope this is a topic for this forum and that it may be of interest to some. Have been lurking for awhile and I've learned some good detail from this forum. Many profs and +reps to those that share their knowledge. I've read many, often passionate, opinions on trimming fan leaves during flowering. Seems some do but many don't. Given the light saturation point of any type of plant (don't know how to measure or estimate it) and all other factors being provided in ample and correct supply (light, water, CO2, temperature, oxygen (in the roots), nutrients, and ph), in an enclosed small footprint grow area, canopy layer is about the only remaining factor a grower can influence to increase flower production. Since light saturation occurs from the top down upper leaves get the total amount of light they need (assumption) and any unused light is wasted. The light cannot penetrate to second and third layers of the canopy so inefficiency occurs. It seems to make for good practice to remove any upper canopy fan leaves so the available light can penetrate to the lower levels of the canopy and the lower bud sites. I'm not advocating wholesale slaughter of the plant, rather selective trimming leaf by leaf so light can penetrate to the lower levels. I understand the principles of LST, SCROG, and SOG and view selective trimming as a plus to these methods. Is this a practice that is used by the experienced horticulturists herein? If so is there anything to elaborate on regarding this vigorously debated topic?
I am doing something along this lines presently. However, I only take off the large fan leaves that are already showing signs of dying off. Right when the first signs appears I snap them off to allow the plants to use their energy elsewhere and or allow light to penetrate to the lower branches. I figure if they are showing signs of dying (even slight) then it won't hurt to remove them and the fact they are showing signs means the plant is done with them anyway. But to just remove healthy green fan leaves is not something I would do, no matter what phase the plant is in.. the leaves act as solar panels to collect light and thus conduct photosynthesis.
Very nice looking setup mj. I like the looks of the environmental controls. Not to mention the results you are achieving. What is also on my mind regarding this topic is what effect flowering has on photosynthesis. Seems the academics haven't yet proven that definitively for any crop species. At least my current state of inquiry indicats so. It appears you have a very controlled environment, suitable as a lab so-to-speak. If I may be so forward; would you select one of your specimens and conduct a test, sharing the results with the community? Perhaps report on what happened, observable differences, yield, etc. I'm just saying.... it might be interesting to see actual tests conducted in a lab-type setting and provide results for further study of getting the most yield from the yield potential of the plant. Thanks for your thoughts.
removing dead or almost dead fan leaves is a good thing, the plant stops wasting energy tring to fix them, and dead leaves bring all kinds of problems like bugs pests and diseases. but the large main fan leaves is what produce the most energy for your plant so its best to leave them alone selective pruning is a process where you remove certain stems and leaves that are not getting enough light(lower branches) so that the plant stops fosucing its energy on the popcorn buds that get no light and puts that energy into the top of the canopy where all the action is, because this is where the light is at, the top. another form of selective pruning is to trim select tops to get the plant to grow in a certain shape that is desired, but neither of these "selective pruning methods"advocate cutting large fan leaves. the only time there is wasted light is if there is light hitting the floor somwhere, in this case its best to bend or tie down the plant to cover up the wasted light patch. to get the most yield from a plant there is a few factors that play a major role. the first being light, you want adequate light for your plants to grow healthy and at a good pace. the second factor is environment, temps must stay stable and humidity in proper range and good levels of co2. the third is good ferts, now im not saying to boost your plants like crazy, but just good wuality complete ferts will do the trick. all this adds into the plants health and the way a plant performs, you cannot get a plant to perform better than its genetic optimal performance, therfore if a plant is optimumly healthy at all points then it will produce optimum yield. over booding a plant will not make it grow faster but more likley intoxicate it or hinder its health leaving you with an unhealthy plant and an unhealthy yeild. now you may think all this is off topic but it all comes back to the same thing, when you cut a plant you hinder its health and at takes tyime and energy to rebuild and heal its self, the large leaves collect and produce the most energy for the plant so removing them the plant would take even longer to repair the wound. removing lower branches are alot less stressfull on the plant, they will most likly take longer to mature and did not recieve enough light to make anything dense, so removing them is helping the plant to redirect its energy to the top buds and branches, IMO i cut just the lower branches that dont recieve much light but i do it all at once when i switch to 12/12, after that i dont touch nothing but dead leaves.
I don't disagree with anything you say joe_. Especially about energy being diverted to repair an injury. I wonder what's going on inside the plant when it has to do that and what, if anything, is taken away from the flowering process.
IMO what is deverted is a day or 2 of production is sacrificed to repair the wounds once it has repaired its self it will divert the extra energy to the fastest growing tip that recieves the most light
I'm not real big on horticulture knowledge, I mostly rely on GC and my friends, my one friend (who also grows) says to leave the leaves, The plant stores energy up in them and uses that energy when it is in flower mode. Hence the yellow/brown dying leaves ususally at 6-7 weeks into flower.
I have read elsewhere that once the plant switches completely from vegetative to flowering growth some leaves are used as sinks for unwanted waste products. If you remove these dump sites early on then there will be a buildup of toxins and the plant will start to dispose of other leaves that may have still been needed to photosynthesize. For the most part I agree with you in removing dying leaves but do so with moderation IMO you should definitely leave a couple to die off completely, just my $.02.
Only remove leaves that are more than 50% dead if you remove them at all. Removing large fan leaves is very stressful for plants. If you aren't an expert, you're better off leaving the plants alone. Cutting large fan leaves to increase light penetration to the lower branches is not a good idea.
I heard also, and maybe because it is sunlight and not artificial light, that the ladies don't need direct sunlight at all, you can actually hide your plants in tree tops. Not sure about this but it sounds somewhat plausable.
Can you please give me a link to this info you mention? I've been growing since 1980 and have never read anything along that lines (does not mean it's not out there). I like to verify "I read somewhere" before I consider it as legit. Thanks...
I would also like to read the article on toxin sink myself. I think the topic dovetails nicely with the question of the effect flowering has on photosynthesis. I'll do some searching on the toxin sink. Again, I'm only discussing selective trimming and not wholesale slaughter. Canopy management at the leaf level. There is a limit to light absorption capability for a given surface area. Inside growing paramters get pushed to the maximum and for smaller wattage grows every little bit helps...maybe. Thanks for the thoughts. In my research on photosynthesis I was never able to find any information regarding toxin sink. I don't know what the plant does with "toxins" per se.
I started the thread so I should at least contribute to it. If you wish to dialog further on the topic we could do so herein or a separate thread. If this is the end of it then thank you for reading and contributing. As a layperson my initial interest in this subject was how one can improve photosynthesis efficiency (PE) in a small footprint and enclosed growing environment. Just throwing more lumens or more CO2 into a tight grow space isn't necessarily going to increase the results of flowering compared to the effort (expense) expended. There's a balance to be obtained and a fixed yield potential for every growing environment. Not everyone has the luxury of space, stealth, and expense to work with. Having researched this topic more since my initial vague posting my own conclusion on the matter is this. The topic of PE remains as vigorously debated among academics as any one of the controversial subjects that is debated amongst the population in general. I had no idea the subject was so controversial. That said there are compelling arguments on both sides that present their cases quite well – to trim or not to trim. Anyone interested in the detail of these arguments should do an advanced search on the subject of photosynthesis efficiency limiting your domain to only “.edu†sites. Avoid the “.com†sites. As a result of my research I will choose to employ methods of canopy management as a means to increasing PE which result in the most benefit to flower production and plant health. These methods will only include plant rotation, LST, and selective singular trimming of leaves (Maybe one day I will try SOG instead of LST). All other environmental variables will be maximized for potential (air, temperature, nutrient uptake, etc). If a single leaf is shading 100% of the light over a bud and the bud leaves directly below it and I can not remedy that by rotation or LST I will surgically remove that single leaf so that at least partial light penetrates the lower canopy and bud sites. Tying the leaf back so light penetrates the lower canopy doesn't “improve†PE in this case as opposed to trimming the leaf because no light means no photosynthesis. So if it's tied back or trimmed off the leaf isn't conducting photosynthesis because it doesn't have any light hitting the green surface area of the leaf. Make sense? On the other hand, no lower bud sites, no problem - “If it ain't broke don't fix it†- leave the leaf alone and don't trim it or tie it back. I think the overall best policy is to not trim but if necessary only trim selectively and minimally and perhaps focus more on air circulation and respiration as a means to improve PE. If your grow environment is less than optimal to your expectations (elongation, lack of branching, lack of flower site formation, unhealthy physiology etc.) then you should look at the overall PE scaled to your particular environment. PE is at the top of the pyramid of plant physiology. It is the sum total of all other inputs combined (light saturation, water, O2, CO2, nutrients, etc). It pays to understand what that means as a potential for improving crop yield opposed to just throwing more of anything towards improving crop yield without understanding what may be currently lacking or by understanding how to maximize your particular custom environment. I'll move on to other thoughts now. Hope I didn't get too far off into the weeds so-to-speak on this journey. Good growing to all and to all G'day.
So I looked for the article again but couldn't find it sorry. I'll keep looking but for now I got nothing but my memory. Regardless, this I know for sure: when leaves start to die off the plant is reabsorbing all of the stored energy to use in flowering. So you shouldn't remove leaves until they dry out.
1 other thing. It seems like this thread is more focussed on getting light to lower branches but as a side topic I think that having a single light source, compared to 2 or 3, contributes a lot to inefficiencies. Personally I would prefer 2 400W lamps on either side of my plants tilted slightly inward over a single 1000W lamp right overhead. I hate having to rotate my plants under the bright spot and I think I could get better results.
I agree with this. I use 2- 400watt setups for my veg room and 2 - 600watt setups for my flower room. I will at some point be adding at least 1 more 400 and 1 more 600 to each room.