IN MY HUMBLE OPINION, When a large FAN leaf starts yellowing, say it is half yellow, that means in the photosynthesis process, that leaf has ate nutes, sucked in some LIGHT and made food for the plant and buds and NOW, half of that is gone, or used or consumed. Well, what about the other half? Can it not it's energy still be used or consumed?
AND when it is ALL consumed or used, that leaf will naturally just fall off.
Years ago I tried removing lower fan leaves to allow more Light to penetrate in. When i did, the plant went into shock for a day or two, and quit eating or only ate half as much, and just went on "stand by" mode. Then, after a day or two, suddenly, I saw that big fan leaf replaced by a new leaf, and I saw my plant use the energy to replace that leaf, more than it used it to grow bigger and make more buds or bigger buds.
I now believe that removing fan leaves is pointless, and that a leaf has a purpose and will serve that purpose until it is dead. Then it will fall off.
Don't ever remove fan leaves before harvest for several reasons.
1. The fan leaves MAKE AND STORE energy for the plant. The fan leaves are doing a process called photosynthsis, and it is the most important part or task or job the plant does, to make it grow. They make the FOOD, the sugars and carbs needed to grow.
If you remove a FAN leaf, the plant will stop growing taller until it can replace that removed fan leaf.
Removing a healthy fan leaf is a big waste of time..they are rapided replaced,, unless you are in the last few weeks of flowering.
2. Even if the fan leaves are yellowing in late bloom I do not remove them until they are almost ready to fall off. The yellowing in the fan leaves at late harvest is the plants metabolism at work. She is transferring all stored energy in the fan leaf to bud production. It is the easiest source of energy she has late in life.
From the Growers Bible by Jorge Cervantes:
Leave leaves alone! Removal of healthy leave hacks up a healthy plant. Removing large or shade leaves DOES NOT make plants more productive. This practice DOES NOT supply more light to smaller leaves and growing tips. Plants need all their leaves to produce the maximum amount of chlorophyll and food. Removing leaves slows chlorophyll production, stresses the plant, and stunts its growth. Stress is a growth inhibitor. Remove only dead leaves or leaves that are more than 50 percent damaged.