Lighting times

18/6 causes fastest prebloom accordingly to Hose Cervantes Growers bible.

18/6 is the most efficient/effective light cycle. Any more than 18 hours is really a waste of electricity as cannabis can only grow so much during any 24 hour period. Although there will be a very small increase with 20 hours, the extra over 18 hours is so small that you are basically wasting electricity for 2 hours for very little return. Plants do actually need to "sleep" and undertake certain metabolic processes which it can not do during the day and I personally feel 4 hours "sleep" is not enough. The way I like to think about it is; 2 hours to "wind down", 2 hours to "repair" and 2 hours to "get ready" for the next day. Plants are organic living beings that should be nurtured with love and empathy. They are not machines that are run at full speed all day every day, because something will break. Once an over worked and thrashed out plant situation occurs, this is when plants start doing strange things like grow male flowers or refuse to mature properly, and once that happens, you can say goodbye to quality flowers and end up with "product", that for all intents and purposes looks ok, smells ok but just doesn't quite have the "wow" factor. Hope this helps,.... Organoman.

It really depends on what you choose! cannabis is a photoperiod plant which means if it gets less than 12 hours of uninterrupted night cycle then it'll remain in vegetative state until those conditions are met (inducing flowering by increasing the night cycle to 12/12) Although most people like to go with 18/6 which is considered the optimal for veg/auto-flower, some also believe 20/4 schedule is more beneficial due to the increased day cycle. While this may be a possibility a light/radiation stress will most likely appear if proper distance from lamp is not maintained, and is not recommended to try by inexperienced growers. I believe you can't go wrong with an 18/6 schedule but if you want to experiment and push your girl/s to the limit then go with a 20/4 schedule but be mindful of them!! Hope this helps! Good luck and happy growing :)