Forcing early flowering because of light pollution and dropping temperatures...

Hi, I know I need 12 hours on, 12 off for my plants to flower. I have read a lot about the smallest amount of light stopping them from going into the flowering stage. My plants are on a balcony. Lots of artificial light comes from the opposite tower block and all of the tower blocks around, roads and my house. Is this going to be a problem? Should I make a room for them that is completely dark? Would putting bin bags over them be safe for the plants? I would love to just leave them to flower naturally but I am worried about all the artificial light around and the dropping temperatures that are coming soon! Many thanks for any help and/or advice. x
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Light is the same for plants as it is for animals. Would you like to sleep with lights on? While I'm not sure exactly your setup, it would be advised to ensure they are getting their 12 hours of "darkness", sans light. I prefer to actually give my flowering girls only 11, even.

I would cover them cover with a table and table cloth remove in the am

Thanks guys