Trimming marijuana leaves

A question from a fellow grower:

I have very technical questions for you, such as the 2 in the subject line. Trimming, how often? Is there a maximum number of fan leaves to remove per plant, per day?
When is the best time to trim? In the AM after dark cycle? Just prior to dark cycle, does it matter? The scientist in me believes there is an optimal time of day for trimming. Most likely after the carbohydrate usage going into the light cycle.

Most fan leaves should not be removed, none per plant per day.

The large fan leaves are the energy producing solar panels. Large fan leaves can be removed sparingly if they are blocking a significant branch, which may have a bunch of leaves itself and potential flower developing sites or flowers, but otherwise do not cut off your fan leaves. Depending on how many nodes tall your plant is, you might top it, depending on your style of training/pruning, but otherwise you almost never want to cut a lot of healthy parts of the plant off.

As far as when, yes it is actually best to prune and train a little bit before the lights come on. This of course requires a special green light so you can see what you are doing without interrupting the dark photo period schedule. even the little bit of light from opening the door or what have you is not good for the light schedule, so no light at all should be leaking in during the dark period. If this is too troublesome, then the pruning or training is best done right after the lights come on, this gives the plant the entire rest of the light period to grow, heal and repair before the following dark period, when wounds will be more susceptible to diseases like mold/fungi.

Here here! :mrgreen: I know of no plant whereas it is proper procedure to remove fan leaves.