mogie
Well-Known Member
http://www.drugs-forum.com/growfaq/GrowFAQ%20Basic%20Topics.htm
Fan leaves store mobile nutrients, these stored nutrients are essential in the later stages of flowering. When flushing a plant the fan leaves will lose their color quickly. This is because the nutrients are being mobilized to the atypical meristem (grow tip, bud site). Draining your fan leaves with a flushing period will increase floral development (Ca, 13.03.2002). Fan leaves therefore serve as a nutrient deficiency buffer zone for the plant (Higstar, 03.13.2002).
Nutrient burn usually causes bottom leaves begin to die however DaGnome (03.15.2002) observed that if you do not remove the leaves then they will absorb damage as premature removal generally results in more leaf loss. However if growing hydroponically under ideal conditions it could be argued that fan leaves serve as a nutrient buffer is a moot point.
WHEN AND WHAT TO TRIM IF AT ALL
To trim or not to trim that is the question. Try everything for yourself. Try it all ways. (The Crazy Composer, 13.03.2002). Simply put there is no universal answer it depends on how your are growing when where and what you trim (Cardboardbill, 03.13.2002)
Genetic Variance
Cannabis phenotypes play a large part. A strain with very few leaves and long internodes will need a lot less trimming - if a trimming technique is even adopted. A strain with a surplus of leaves and short internodes would require more thinning to get the same amount of light to the lower buds (The Crazy Composer, 13.03.2002). Cannabis varieties from high sunshine equatorial areas like thai sativa have thin leaves most likely due to more light than say a indicia plant from afghan regions have wider fan leaves due to less light intensity in their natural environment (Lebman, 03.20.2002).
Remove non productive dead leaf material
Here are some signs to look for when removing foliage. Leaves that have reached their final size and are ageing will stop producing chlorophyll and start changing to a lighter color, often yellowing and showing purple petioles (leaf stems). This is when the leaves' capacity to produce sugars starts to diminish, so they are the ones to take out of the way to allow Sunlight to fall on the younger leaves that are producing at a higher rate. The older leaves, even though larger, are no longer very productive once they are not dark green anymore. By the time they start looking pale or discolored, they are not contributing anything to the plant at all. Obviously, the lower leaves are the oldest and the first to age. Old leaves can be removed at any time they are shading younger ones, but try to never remove a leaf in its expanding stage because it is producing at full power (Leaf, 03.13.2002.
Outdoors, fan leaves serve an additional and very important purpose of protecting the buds from the elements and predators. These leaves often become damaged in the course of doing their duty, and will then wither or break off (Jeast, 03.13.02). However depending on the humidity of the growing climate Leaf (03.13.2002) suggests to trim most leaves that show signs of age, are dull in color, yellowing, and obviously any brown or spotted leaves that have bugs or bug damage to prevent mould.
To Increase Lower Bud Development
Light efficiency decreases with distance. The inverse squared light rule states that illuminance is inversely proportionate to the square of the distance from the light source.
Removing the largest area of photosynthesis that is closest to the light source simply to benefit smaller leaves growing out of the but sites that are further away is not logical when growing indoors"(Smokinrav, 03.15.2002). Cultivating outdoors under the sun, the fan leaves don't create nearly as much shade as they do indoors (~shabang~, 03.13.2002). This is consistent with the inverse squared light rule; the sun is 149,597,890 km away so a few feet has no real effect on intensity. This suggests that a trimming benefit could be achieved outdoors as opposed to indoors however leaves only absorb about 15% of the solar energy that hits them, the other 85% passes through except for green light which is reflected, therefore removal of fan leaves would only provide a 15% increase light transmission outdoors (Shipperke, 03.15.2002).
Jeast (03.12.2002) removes fan leaves that are yellowing or starting to yellow (these are usually on the lower stems) and also mid-stem fan leaves that are shading buds. He always try to retain the upper 2 - 3 sets of fan leaves indoors as he believe they are the ones that are truly "working". The concept of the upper fan leaves doing all the work is consistent with effect of the inverse square rule on lighting intensity indoors and the flow on effect for photosynthesis. In support for trimming HyGradeChronic (03.25.2002) states selective trimming benefits lower floral development, allowing the buds to fill out and tighten up better. However he does mention that humidity must be kept to a minimum as leftover stems from the leaf can develop mould unless kept at optimum humidity. Another flow on effect to leaf trimming mentioned by HydradeChronic is that it takes seven to ten days longer for floral development to finish, but the resulting florescence is at its peak from top to bottom.
An alternative to trimming to increase light to lower floral clusters is to use a light mover on a single plant the results are better thanks to the better penetration of light at different angles. Even simple under lighting and side lighting works well to counter fan leaves by adding extra light where it would not normally get (Vapour, 03/13.2002).
Increase upper bud development
What folks need to focus on is the causes of premature leaf drop as that negatively affects yields. If you've read my posts over the years, I try to pound that issue home whenever given a chance. After a good root development, the most important element in floral production is the retention of healthy leaves (Thunderbunny as citied, by Nietzsche, 03.13.2002).
Green Reaper (03.12.2002) suggests that large leaves actually take more energy to maintain than they produce. In contrast Thunderbunny (as citied, by Nietzsche, 03.13.2002) states that when a leaf no longer serves a productive purpose, the plant will remove the leftover metabolites from the leaf, which causes the old spotty, yellowing, necrotic image and then the leaf drops. Once that leaf is gone, a percentage of what would be available carbohydrates for future plant growth is diminished in direct relationship to the loss. The mobility of plants sugars and nutrients suggests that fully developed fan leaves are sources not sinks. Whether developing fan leaves are a sink or a source however is not as clear. An actively growing leaf may be a sink, using energy from the other parts of the plant to fuel their development (George, 03.20.2002). Older developed leaves and that are sources. However there is no evidence to support that during the plants life cycle the development of fan leaves takes more energy then a fully developed fan leave provides, that is to say sink phase is greater than the source phase (Nietzsche). It would also seem illogical from an evolutionary point of view that a plant would evolve to produce leaves that take more energy to sustain then they produce (~shabang~, 03.13.2002).
Trim fan leaves in the last 14 days to help speed up flushing
It helps speed up the flushing process and or makes flushing unnecessary (Homemadepot, 03.13.2002). However the leaves should naturally yellow, too much green in the leaves translates to too much "green" taste in the leaves in my opinion (Bigislandbud, 03.14.2002).
Reducing the Stretch
If trimming fan leaves reduced the stretch it is likely that this occurred because it takes away from the plant's available energy stores and energy generators (~Shabang~, 03.13.2002). This method of reducing the stretch should only be used if absolutely necessary, other options include chemical treatment may be a more viable option.
HOW TO TRIM IF YOU CHOOSE TO DO SO
If you decide to trim your fan leaves, one should always do it by clipping the petiole about halfway between the base of the fan leaf and the stem/branch. Allow the remainder of the petiole to dry up and fall off on its own. This will help protect the plant from risks of infections. They should never be stripped or broken off at the base of the petiole as that would be expose more chance of infecting the plant. Petiole is the he foot stalk of a leaf (10k, 03.16.2002)
Leaf (03.13.2002) believes that excessive leaf trimming and branch pruning will cause the plant to use extra energy to repair itself. However, trimming must be done from time to time, for the longer a plant is left untrimmed, the more material must be removed at one time, therefore the greater the damage that the plant will need to repair. Do not trim fan leaves during veg either, unless they turn yellow. The first real pruning starts when going into 12/12 (Jeast, 03.13.2002). When trimming and pruning, I try to ensure that I do not cause the plant to 'bleed'. Leaf tries to pinch off shoots and leaves with my fingernails as opposed to leaving a clean cut. One thing to remember is every time you cut into any part of a plant, you are exposing the inside of the plant to fungus and bacteria (Leaf, 03.13.2002).
Tuck instead of trimming
Another method is to tuck your fans leaves under to expose the buds, don't forget that even though they wont be getting as much light they are still photosynthesizing and more importantly exchanging gases storing nutrients, and building sugars which the bud then converts into THC and other cannibinoids (Ca, 13.03.2002)
Fan leaves store mobile nutrients, these stored nutrients are essential in the later stages of flowering. When flushing a plant the fan leaves will lose their color quickly. This is because the nutrients are being mobilized to the atypical meristem (grow tip, bud site). Draining your fan leaves with a flushing period will increase floral development (Ca, 13.03.2002). Fan leaves therefore serve as a nutrient deficiency buffer zone for the plant (Higstar, 03.13.2002).
Nutrient burn usually causes bottom leaves begin to die however DaGnome (03.15.2002) observed that if you do not remove the leaves then they will absorb damage as premature removal generally results in more leaf loss. However if growing hydroponically under ideal conditions it could be argued that fan leaves serve as a nutrient buffer is a moot point.
WHEN AND WHAT TO TRIM IF AT ALL
To trim or not to trim that is the question. Try everything for yourself. Try it all ways. (The Crazy Composer, 13.03.2002). Simply put there is no universal answer it depends on how your are growing when where and what you trim (Cardboardbill, 03.13.2002)
Genetic Variance
Cannabis phenotypes play a large part. A strain with very few leaves and long internodes will need a lot less trimming - if a trimming technique is even adopted. A strain with a surplus of leaves and short internodes would require more thinning to get the same amount of light to the lower buds (The Crazy Composer, 13.03.2002). Cannabis varieties from high sunshine equatorial areas like thai sativa have thin leaves most likely due to more light than say a indicia plant from afghan regions have wider fan leaves due to less light intensity in their natural environment (Lebman, 03.20.2002).
Remove non productive dead leaf material
Here are some signs to look for when removing foliage. Leaves that have reached their final size and are ageing will stop producing chlorophyll and start changing to a lighter color, often yellowing and showing purple petioles (leaf stems). This is when the leaves' capacity to produce sugars starts to diminish, so they are the ones to take out of the way to allow Sunlight to fall on the younger leaves that are producing at a higher rate. The older leaves, even though larger, are no longer very productive once they are not dark green anymore. By the time they start looking pale or discolored, they are not contributing anything to the plant at all. Obviously, the lower leaves are the oldest and the first to age. Old leaves can be removed at any time they are shading younger ones, but try to never remove a leaf in its expanding stage because it is producing at full power (Leaf, 03.13.2002.
Outdoors, fan leaves serve an additional and very important purpose of protecting the buds from the elements and predators. These leaves often become damaged in the course of doing their duty, and will then wither or break off (Jeast, 03.13.02). However depending on the humidity of the growing climate Leaf (03.13.2002) suggests to trim most leaves that show signs of age, are dull in color, yellowing, and obviously any brown or spotted leaves that have bugs or bug damage to prevent mould.
To Increase Lower Bud Development
Light efficiency decreases with distance. The inverse squared light rule states that illuminance is inversely proportionate to the square of the distance from the light source.
Removing the largest area of photosynthesis that is closest to the light source simply to benefit smaller leaves growing out of the but sites that are further away is not logical when growing indoors"(Smokinrav, 03.15.2002). Cultivating outdoors under the sun, the fan leaves don't create nearly as much shade as they do indoors (~shabang~, 03.13.2002). This is consistent with the inverse squared light rule; the sun is 149,597,890 km away so a few feet has no real effect on intensity. This suggests that a trimming benefit could be achieved outdoors as opposed to indoors however leaves only absorb about 15% of the solar energy that hits them, the other 85% passes through except for green light which is reflected, therefore removal of fan leaves would only provide a 15% increase light transmission outdoors (Shipperke, 03.15.2002).
Jeast (03.12.2002) removes fan leaves that are yellowing or starting to yellow (these are usually on the lower stems) and also mid-stem fan leaves that are shading buds. He always try to retain the upper 2 - 3 sets of fan leaves indoors as he believe they are the ones that are truly "working". The concept of the upper fan leaves doing all the work is consistent with effect of the inverse square rule on lighting intensity indoors and the flow on effect for photosynthesis. In support for trimming HyGradeChronic (03.25.2002) states selective trimming benefits lower floral development, allowing the buds to fill out and tighten up better. However he does mention that humidity must be kept to a minimum as leftover stems from the leaf can develop mould unless kept at optimum humidity. Another flow on effect to leaf trimming mentioned by HydradeChronic is that it takes seven to ten days longer for floral development to finish, but the resulting florescence is at its peak from top to bottom.
An alternative to trimming to increase light to lower floral clusters is to use a light mover on a single plant the results are better thanks to the better penetration of light at different angles. Even simple under lighting and side lighting works well to counter fan leaves by adding extra light where it would not normally get (Vapour, 03/13.2002).
Increase upper bud development
What folks need to focus on is the causes of premature leaf drop as that negatively affects yields. If you've read my posts over the years, I try to pound that issue home whenever given a chance. After a good root development, the most important element in floral production is the retention of healthy leaves (Thunderbunny as citied, by Nietzsche, 03.13.2002).
Green Reaper (03.12.2002) suggests that large leaves actually take more energy to maintain than they produce. In contrast Thunderbunny (as citied, by Nietzsche, 03.13.2002) states that when a leaf no longer serves a productive purpose, the plant will remove the leftover metabolites from the leaf, which causes the old spotty, yellowing, necrotic image and then the leaf drops. Once that leaf is gone, a percentage of what would be available carbohydrates for future plant growth is diminished in direct relationship to the loss. The mobility of plants sugars and nutrients suggests that fully developed fan leaves are sources not sinks. Whether developing fan leaves are a sink or a source however is not as clear. An actively growing leaf may be a sink, using energy from the other parts of the plant to fuel their development (George, 03.20.2002). Older developed leaves and that are sources. However there is no evidence to support that during the plants life cycle the development of fan leaves takes more energy then a fully developed fan leave provides, that is to say sink phase is greater than the source phase (Nietzsche). It would also seem illogical from an evolutionary point of view that a plant would evolve to produce leaves that take more energy to sustain then they produce (~shabang~, 03.13.2002).
Trim fan leaves in the last 14 days to help speed up flushing
It helps speed up the flushing process and or makes flushing unnecessary (Homemadepot, 03.13.2002). However the leaves should naturally yellow, too much green in the leaves translates to too much "green" taste in the leaves in my opinion (Bigislandbud, 03.14.2002).
Reducing the Stretch
If trimming fan leaves reduced the stretch it is likely that this occurred because it takes away from the plant's available energy stores and energy generators (~Shabang~, 03.13.2002). This method of reducing the stretch should only be used if absolutely necessary, other options include chemical treatment may be a more viable option.
HOW TO TRIM IF YOU CHOOSE TO DO SO
If you decide to trim your fan leaves, one should always do it by clipping the petiole about halfway between the base of the fan leaf and the stem/branch. Allow the remainder of the petiole to dry up and fall off on its own. This will help protect the plant from risks of infections. They should never be stripped or broken off at the base of the petiole as that would be expose more chance of infecting the plant. Petiole is the he foot stalk of a leaf (10k, 03.16.2002)
Leaf (03.13.2002) believes that excessive leaf trimming and branch pruning will cause the plant to use extra energy to repair itself. However, trimming must be done from time to time, for the longer a plant is left untrimmed, the more material must be removed at one time, therefore the greater the damage that the plant will need to repair. Do not trim fan leaves during veg either, unless they turn yellow. The first real pruning starts when going into 12/12 (Jeast, 03.13.2002). When trimming and pruning, I try to ensure that I do not cause the plant to 'bleed'. Leaf tries to pinch off shoots and leaves with my fingernails as opposed to leaving a clean cut. One thing to remember is every time you cut into any part of a plant, you are exposing the inside of the plant to fungus and bacteria (Leaf, 03.13.2002).
Tuck instead of trimming
Another method is to tuck your fans leaves under to expose the buds, don't forget that even though they wont be getting as much light they are still photosynthesizing and more importantly exchanging gases storing nutrients, and building sugars which the bud then converts into THC and other cannibinoids (Ca, 13.03.2002)
.....update. 
