Question about switching to 12/12

I am currently running 18/6 lights on from 3pm til 9am... My question is when I switch to 12/12 do I have to do 3pm to 3am lights on, or could I do something like 6pm to 6am lights on ???

You can change the light schedule, it won't matter.

Some say to leave the lights off for 24hrs then start the 12/12

And some say run 11 on and 13 off to get better results.

12/12 is the best for flowering .but every one has there own little way of doing things ..and you must do some diggin and see what you can find out..im on 12/12 ..and yes change to what ever time you like

when you flip to flower, you can choose whichever schedule you like. some do an extended dark period prior to flowering. i tried it once, but didn't really see any difference in not using it. stick to a simple 12/12 flower time. no need to get fancy. 12/12 is tried and true...

Some varieties prefer 11/13 some prefer 13/11 but almost all of them will do just fine with 12/12 so I just stick to that for everything.

If you want to shift your start time from 3PM to 6PM when you move your plants to the flower room, do it in such a way that they see a longer night rather than a shorter one. The reason is because they key on the length of night so with a long night they get the correct message and they won't notice the change in start time.

I try to run my light 11 pm to 11 am so my room stays warmer at night when it's cool outside//just a thought

Set your 12/12 to whatever time is most convenient to you. There's no special way of doing the flip to 12/12.

SupraSPL said:

Some varieties prefer 11/13 some prefer 13/11 but almost all of them will do just fine with 12/12 so I just stick to that for everything.

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i have never heard of this before. is this an indica or sativa thing? i've heard of the 11/13-13/11 thing, but not that it is something different varieties prefer. which varieties?

Meast21 said:

I am currently running 18/6 lights on from 3pm til 9am... My question is when I switch to 12/12 do I have to do 3pm to 3am lights on, or could I do something like 6pm to 6am lights on ???

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Personally, I take all that into account prior to ever turning on the MH. The time to make that choice is either while the seeds are soaking or the cuttings are rooting (my t-5 runs 24/7 when on). It's not the end of the world if you haven't but for me my lights come on the same time throughout the whole grow. If you were to change the clocks on your grow I'd suggest keeping the lights on for a night or two and then adjust your timer. Sort of the reverse of turning the lights out for a couple of days at the beginning or the end of a flower cycle.

SnapsProvolone said:

And some say run 11 on and 13 off to get better results.

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This is generally only done on a sativa with an extremely long flower time. Some believe it shortens the calendar by a tad bit. I've yet to run anything that was that predominantly sativa were I've needed to try this. But I do have some angels breathe (mango haze x afghan haze) in the pipeline now that has a chance of developing into a 13+ weeker. If they do I plan on trying this around week 10 if the finish line is no where in sight. It says to discard anything over 13 weeks - I may not grow it again but I'm not throwing anything away after 18 weeks or so. If I'm into it that long I'm seeing it through to completion.