Some equatorial landraces seem like they may benefit from 12/12 from birth , I’ve read and heard talk of the plants flowering when genetically ready vs being tricked into it by going from 18/6 to 12/12. With the few modern hybrid seeds I’ve tried this with I’ve experienced plants that went into flower almost immediately resulting in like maybe three joints worth of herb and I’ve had plants that vegged for 4-6 weeks before showing sex and starting to flower. When working with landraces it seems simulating the photoperiod of that strains origin could be beneficial.
With seed plants I prefer to veg under 18/6 till they are showing signs of maturity and then flip to 12/12 or 11/13, this gives me more over all control of there shape and size.
I know most of the time with seeds they tend to not want to flower until there ready if you try to go from veg to bloom at to young of a age.
I’ve generally heard it done when running long flowering sativas from seed, haven’t tried it myself unfortunately so I can’t speak to any personal results
Here are some pics!
This 1st one was when they were being moved to the tent on 12/12 there was 9 total and I ended up with 4 females this was on December 9th 2021, also I have a old dishwasher I converted to a seedling cabinet with a few LED bulbs and a small fan that I use till they are out of the soil a week or so because my dark period is 12 degrees Celsius.
This here 2nd pic was 1 month after the 1st pic. This was January 9th 2022 , the 3rd pic in January 13th, also the pots are 1.5 gallon but only holding 1 gallon of soil, my plan is 12/12 basically from seed (1 week 24hr light) with 12 plants in my 2x4 tent in 1 gallon pots the 1st 4 I didn’t have 1 gallon pots I now do.
This here 4th pic is just a bud this was the same time the 2nd pic was taken on the January 9th
This here picture was from January 29th that little runt is now gone it wasn’t growing at all.
This picture is February 4th
And these pictures are from last night February 10th
My goal is to always have 12 plants in the tent on 12/12 and to always have something ready in the seed cabinet to go into the tent as something gets harvested, this will allow me to grow a variety of strains and should have a steady supply, I’ve found when I veg out plants than flower them I run out in between grows so this is my attempt to eliminate that, plus it’s part of the fun experimenting lol
I want to see if I can get a small crop in before summer outdoor so I planted a few of my auto seeds in the mulch in my flower tent so far 3/4 popped above ground
They might stay super small on the 12/12 cycle. This was an Auto I ran on 12/12 from seed for a solo cup competition. From the autos I have run, I think they need the hours of light to get bigger. Good luck though, and I’ll be following along!
I have some DocDs velvet buzzsaw and lemintz from corey im gonna try this with, it will be the second time I run some real sativa. Ill probably veg a couple weeks but not much since headroom is at a premium. I tried Burmese Pure outside 2 seasons ago and had to bring them in and try to finish under the lights.
I got the trics to the cloudy stage and pulled it. Im sending the balance of these beans to Doug to give away, all you sativa lovers keep your eyes open.
I’m doing this right now actually, filling the gaps left from males. Seeds planted directly into 3 gal pots and 2 seeds into a 7gal. No idea how its going to go but I’m getting nervous as the big girls around them get larger and space seems to be shrinking lol. I’m used to having a packed jungle but airflow underneath is always on my mind and now I’ve taken up any space I could have put my small fan. The seedlings all seem quite happy though and are getting the proper amount of light for their size and age.
Very good point you’re making there.
Seedlings really don’t crave 18 hour of light from the get go.
Come to think of it, it probably contributed a fair bit to the seedlings I’ve lost a few grows ago.
The hours aren’t as important as the dli, aside from triggering flower. My seedlings are in the center row of my tent with a qb on one side of them and a hps on the other, so they are getting the light overlap section of the tent. My meter showed I was at about 1500 and after the calculations puts them right around 18dli. As they get bigger that will increase naturally. I’ll be keeping an eye on that but it might work out perfectly.
If anyone is interested in following a perpetual 12/12 grow, I update regularly.
I went a little over 12 hours of light for a few months but I really prefer perpetual 12/12, otherwise there’s too much shading of the seedlings and depending on the individual plant, some of them grow smaller buds when defoliating, others give zero fucks.
I keep throwing small handfulls of seeds in there as I harvest them or receive them from the wonderful people here.
I’m very happy with the results.
Always said the search function is a great asset in this site 
, was going to open a thread but found this. Thanks for all the info, if anyone has more input about the pros and cons please share… 
12/12 could be good so I could mix autoflowers and some photos for the First Time.Since i should invest in Electric Bill,would you advise It?For example for making seeds and crossing an auto with a photo,a Little breeding until I got a stable auto trait cross
Autos doesn’t matter the light cycle they’re under but they have a shorter lifespan, so that 12/12 just would just help the regs to start flowering faster and “catch” the autos when they’re ready … 
So in therms of yield,I mean,I am not about yield but efficiency with the Money I pay for my Electric Bill.Have someone tried a bunch of autos in 12/12?I do know It depends on lot of factors too,It Is a bit of a stupid question.I don’t know,It Is Just that with autos I cannot properly breed or keep a plant that I like the phenos of
Never tried, but guess they would not reach their whole potential, people go 20/4 with them, less bill but less buds in your case …
As George said it would most likely make them a shorter plant than what they could be under more light…
however, they do grow super fast so you could probably luck out and still get decent sized plants…
Sometimes, with autos, I feel they start flowering when the tap root hits the bottom of what it’s in… so depending on pit size, they might do some good to.
You probably sit at about 40/60 … the 40% being the bigger sizes under 12/12 from start and the 60% would probably be the likelihood of single cola minis, but still pretty good if you’re SoG’ing
Fuck around and find out, every plant reacts in its own unique way to everything.
Nobody can say with 100% certainty.
Just when you think you have it figured out nature will throw you a curve ball.
ive run photos in 12/12 before and actually really liked the results. they stay super small so theyre manageable and you get to try a whole bunch of different strains. yield was shit though. i was getting something like 7g off a 1L pot @ 75-90d.
It’s great for breeding and making seeds though, can open pollinate with more different plants and make more crosses in one go.
Regarding pots for auto’s, I remember @ReikoX switching to deep narrow pots and getting more yield, do I remember correctly?