I agree this is a debated subject and there are differences of opinion. I do believe that there are some situations in which trimming fan leaves is advantageous.

THEORIES WHY TO TRIM FAN LEAVES Increase Lower Bud Development The fan leaves shade lower buds and that these buds do not develop to there full potential because of a reduction in lighting intensity due to shading from upper fan leaves. To conserve energy for upper bud development Trimming fan leaves and lower, shaded branches focuses the plantā??s development on main top buds (Che Bleu, 03. 13.2002). A plant wastes precious energy several ways. A tall plant needs to use energy to build extra stem, and then use extra energy to move water up higher, this is why I believe "scrog" methods are productive. An untrimmed bushy plant causes the plant to expend energy to build elaborate branches and leaves, and then has to use excess energy to supply all these structures. Careful trimming to remove unnecessary branches (which wont produce nice buds) and unproductive suckers will leave more energy for a larger yield. Suckers do exactly as their name suggests, they suck needless energy from the plant which can be put to better use, towards yield (Leaf, 03.13.2002). Reduce the Stretch If fan leaves are trimmed during the early flowering stage, the stretch is reduced (Che Bleu, 03.13.2002). Reducing the stretch might be advantageous in certain cultivation conditions. Speeding Up The Flushing Process Remove some of the fan leaves 14 days before harvest. It helps speed up the flushing process and or makes flushing unnecessary (Homemadepot, 03.13.2002). Reduce The Chance of Mould Removal of dead fan leaves is necessary to reduce the risk of mould. Failing to "clear the airway" can lead to development of mould in the "crowded" areas of the plant (Jeast, 03.13.2002). Scrog growers may also reduce the chance of mould by removing fan leaves due to reduce the level of transpiration. This is because many scrog grows are in a confined space where humidity is a serious problem (DoctorDangerous, 09.04.2002). However with better ventilation it may be necessary to avoid the mould problem (Nietzsche, 09.04.2002). Increase root development on Clones Fan leaves on clones should have their blades cut in half, to make the clone grow slowly while a root system develops (Weezil, 03.12.2002).
PhatJay Reviewed by PhatJay on . Phat Jays 2nd Grow (CFL/Coco) w/pics I started off my second grow today. I am keeping my setup similar to last time, but I am hoping to try out a couple of new things this time round. I am also mixing my own food for this grow. My last grow is still in it's final 2 weeks so I am using a smaller cupboard to start these off and I will be transferring them across to my main cabinet, when the other 2 plants are finished and harvested. :jointsmile: Today I potted up my cuttings and fed them with 200ml 1/4 strength Canna Hydro Rating: 5