18 day light cycle?

I ahve read in the "past" on this forum that an 18 day light cycle is shorter and still produces the same yield. I have not come across any "new" comments or discoveries on this. Any help here would be great, thanks.

Does this mean the lights go on for 18 days then go of for 18 days. I'm totally confused. You must have been reading something about veggin' 18/6

I think he's talking about the 18/6 Light cycle. 18 days and 18 days off seems ridiculous to me. But i'm still a newbie, what do I know?
Not sure what type of seed you're growing, but I have read a lot of articles, journals etc. Seems to me, majority of people grow with 20/4 with their autoflowers. It's working great for me so far. For regulars, 18/6 seems best to optimize growth during veg stage, and 12/12 during flowering.

Hey, 18/6 is the 'industry standard' for the vegetative cycle as u don't need 24 hours of light. I wouldn't recommend more than 18 hours of light. Just my 2 cents.

18 hours on & 6 hours off.. I believe plants need sleep for growth

Hey folks: since the subject is florescent lighting let me suggest another approach. Discount Hydroponics at Riverside, California offers free hydro classes and one of their instructors suggested a progressive light schedule where you start with 20 hours of light and four hours of dark. He was against 24 hours of light and his theory was that even plants need a little R&R. At the end of each week you reduce the light by one hour which increases the dark by one hour. He compared that to what happens in nature. You don't have a sudden drop from 18/6 to 12/12. I think I was the only one in the class that tired it, and it worked for me.

Since then I've used his idea on three grows, all of which have been successful. At about 14 hours of light and ten hours of dark I started seeing pre-flowiering and I had done nothing but follow his lighting schedule. At that point I changed from veg nutes to half strength flowering nutes. After a week of 1/2 strength flowering nutes I go to the full strength flowering formula and I keep them on that until my plants are ready for the pre-harvest flush.

I keep dropping the lights each week until I get down to 14 ours of dark and 10 hours of light and I keep it at that schedule until I harvest. I don't know if it has anything to do with the nutes I'm using; Technaflora's, "Recipe for Success." I've used them exclusively, from seed start or cloning all the way to harvest for about the last four years and I'm very satisfied with their product. I'm doing this under 5,000 and 6,000K T-5 grow lamps and when I change the nutes from vegging to flowering I do the same with the lamps. I use 2700K T-5's for flowering. So far it's worked great for me. It keeps my sugar bowl full and me out of the dispensaries and the light bill doesn't doesn't break the bank. If you decide to try it I hope you'll let us know how it worked for you. For me it's been a very relaxed trouble free way to grow. I hope this helps. HSA

Mj doesn't need a dark cycle to grow roots like other plants do. It's a proven that 24hr lighting does better than 18/6 on veggin'