That's a great link Alaskan1, thanks for sharing it! It's the first time I've seen the diminishing light schedule that goes with the GLR start at 12 hours though. All of the other articles I've read referred to it starting at 11/13.
Having said that, it's all a guide and success can be had either way, no doubt. Because I'm growing Sativa dominant strains, and trying to coax Sativa characteristics, I feel like 11/13 is the way to start. I may have started at 12/12 with indica dominant strains.
While we're on the topic, here's another good article I read recently on 12-1 technique (GLR). I wasn't sure if linking the article was appropriate to site rules, so I'm including the author's name (he has a growing advice column on a pro-cannabis website).
How to reduce the cost of growing cannabis saving 30-50% on your electricty bill using the 12-1 lighting schedule.
Joseph R. Pietri
The biggest innovator in the history of cannabis in my generation is Reinhard Delp. Not only did he invent and is the holder of the patent for ice water extraction, he has been building flower forcers since 1992. His new solar powered Sun-gate is the leader of the industry. He was the first to feminize seeds and sell them in Europe in the late 90’s. His process was done naturally, without the use of any chemicals.
No one is more copied but seldom matched than Mr. Delp, who to me is the top grower of our generation. The first time he impressed me he showed me 2 plants, planted next to one another, 1 completely covered in powdery mildew, the other completely clean and beautiful. He was developing mildew and mold resistant genetics.
In the late 90’s Reinhard brought back the gas lantern routine that you find in any college grade horticulture book, and applied it to cannabis. Cannabis needs only 13 hours to stay in the vegetative growth stage. The 18-6 lighting schedule in vegetation, actually stress your plants, that never get that much light in one-day outdoors. Cannabis is an outdoor plant. Growing indoors you should copy how it grows outdoors. No Cannabis growing in Afghanistan gets 18 hours of light in growth pattern. Most strains today have some part Indica in their genetic pool. Even equatorial strains don’t get 18 hours of sun a day.
The 12-1 lighting schedule is as follows 12 hours lights on, 5.5 lights off, 1-hour lights on, 5.5 lights off, and repeat schedule. The 1 hour on in between off period fools the plants that stay in vegetative growth state! Your immediate savings are 5 hours in energy costs daily, as well as your bulbs and equipment lasting longer. But how do the plants react to this lighting schedule?
You see immediate growth response from your plants, they are happy from the added rest time. By day 14 the plants tripled in size. The plants are bushy with twice as many bud sites without topping or bending, In fact when you top and stretch your plants out, you get many more bud sites than you would have had under 18-6 using same procedure of topping and stretching plant, your growing bigger and better and faster.
So your saving 5 hours daily in energy costs, as well as your excellerated growth pattern which also saves you time and energy and equipment use.
In the flowering stage, never use 12-12, start your flowering period at 11 hours on 13 hours off. When your are growing outdoors each day you get less and less sun light, you should copy the way the sun acts naturally in your indoor grow. So first 2 weeks of flower you go 11 on 13 off, the next 2 weeks you go down to 10.5 on 13.5 off, next 2 weeks 10 on 14 off, next two weeks 9.5 on 14.5 off and the last weeks of flower you should be at 9 hours on and 15 hours off. You’ll get bigger and better buds by copying the way the sun light works on cannabis outdoors.
Cannabis is an outdoor plant and you should copy the way it grows outdoors indoors. The only thing that 18-6, and then 12-12 lighting schedule's do is make the energy companies rich as well as the people who sell lights and equipment, the more you use the more you spend. 12-1 lighting schedule is a more natural way to grow indoors and you well have the best results you have ever had and save as much as 50% in energy costs.
for adding to the discussion. 
is the ONLY place I've ever registered & posted. One reason for me was seeing how LED grows on other forums were getting ridiculed while growers here were breaking new ground and getting high yields with LED's.
