hi guy's,i grow mine in 1ltr pot's(just over one an a half pint's),from seedling to about a foot tall,an hope they go into pre-flower,then you can tell what sex they are before potting up.if you can't do this because of the height,i've put them into 12/12 early to sex them, then potted them up an put them back on 18/6 for 1-2 week's to let the plants root's get established,then put them on 12/12,and had lovely crop 7 week's later...if using clone's i agree with garden knowm an the student...hope this helps..love an respect..spliffbuilder.