Optimum time to change to 12/12

Hi there people, i am just about to flower my first grow and i am a little confused about when is the best time to do this.. Everything i have read has explained that i have to wait until pre-flowers appear so i dont stress the girls into turning hermie but i cant seem to find anything about how mature the pre-flowers have to be...
Can i change the lights when they have just appeared or do i have to wait until they are fully mature??

I am just growing a pick and mix of seeds that were taken out of my bought weed so i dont know what they are and am a bit restricted with height so i want to flower as soon as possible so the plants stay resonably short.

Any help would be great..

I've read that plants will double to triple in height from onset of flower to finish, only a couple of days into flower with mine so don't know for sure, but I flowered mine at 10-18 inches(some grew faster) and was told to flower at 10-14 inches by a buddy.

Ok, The height is not the problem....I would like to find out if i can start to flower as soon as pre-flowers appear or do i have to wait until the pre-plowers are fully mature??

You can flower at absolutely any time.

mismos00 said:

You can flower at absolutely any time.

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Yes, supposedly, the best way to start flowering is give them at least an 18 hour dark period, some ppl do 20 hours or even as much as 32 hours, look into it and then you should feel confident about the switch, good luck!

OK..I have read that u shouldnt change to 12/12 until pre-flowers appear because it stresses the plant into thinking it is running out of time before the end of the season, this causes the plant to make a last ditch attempt to pollinate by turning hermie(this is how they get Feminised seeds by the way). As with all things this is just one opinion and i want to find out if this is the case.
So How mature do the pre-flowers have to be before turning to 12/12??

mismos00 said:

You can flower at absolutely any time.

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Let's see if we can put this together without confusing anybody further!

You can change the photoperiod to 12-12 at absolutely any time. That's the whole idea behind the "12-12 from seed" concept. But even then, the plants won't really start to flower untill they're "mature" enough. Which means when they display preflowers at about 4-5 weeks.

On the other hand, Clones are probably mature enough as soon as they take root - so they will respond quicker to a photoperiod change.

T.H.Cammo said:

On the other hand, Clones are probably mature enough as soon as they take root - so they will respond quicker to a photoperiod change.

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Yes, very true. Clones are the same genetic age as their mother.... or father... lol, which means that as soon as they root, they are ready for 12/12 flowering if the mother had reached sexual maturity.

thank you T.H.Cammo that clears it up for me...I was wondering if i had flowered too early but i cant be...Nice 1