big problem need help

can anyone please help i put my plants into 12hours from seed they now there been flowering for 12 weeks,but at xmas i had to take them on my hoilday and they was in my van for 2 weeks in the cold,then i came home and put them back under the light the bottom fan leaves have gone yellow and so have the ones on the main bud sites,but only 10% of the hairs have gone brown, the buds r big but not that much thc on them.do you think its time to harvest or have i just fu.ked them up.cheers :( :(

flowering for 12 weeks?

I sounds like you may have had to do something most grows would never encounter.. take it on the road...

I personally wouldn't put to much effort on plants that have been flowering already for 12 weeks.