Best way to force flowering while growing outside?

A question from a new grower.

I live in the northeast US. In my research I’ve learned some strains will not finish in time outdoors up here. Bringing me to my question. Is it possible to force flowering earlier on like the 4th of July so they would be finished by late September? I was thinking like black bagging them? Any ideas on this?

P.S. I’m loving this sight very informative! Great job support team! Thanks.

After the Summer solstice in June; The days get shorter. That gives you into July, August and September to finish.