i dont agree ... I have done 18/6 and 24 hour at the same time and really saw no diff. .... save the juice bud - its just not worth the extra electicity it takes.... I truly believe that they need a rest that comes from the dark period to meet the full potential ... but no proof other than my own observations ......
fully agree. i run 24hrs at the moment to make my plants autoflower when moved outdoors where the longest days are only 16hrs.
but in the past have always given the 6 hrs of darkness. some growers swear by 24hr cycles but i dont see much benefit, and as stated above, when running high wattage lights that extra 6 hrs a day can add up to quite some money over time and reduce your profits in terms of yeild to kilowatt hours.
also if you look at a plant in darkness there is a noticable change. it droops slightly as if sleeping, plants dont breath co2 at night either. these factors lead me to a HYPOTHISIS (not proven) that there is something taking place in the plant that is probably good for it.
plants are like people in many ways, if you went without sleep it would mess with you.
and stretching as it pertains to light is more in the spectrum than cycle. plants grown under 2500k tend to stretch more than those under 6500k. thats why some growers use combination high pressure sodium and metal halide in flowering rooms