Ive grown outdoors in michigan for some years now and we can grow some monsters trust me ivee grown them, but you gotta be carefull if you dont get a strain that will finish before the first frost your plants could have to get pulled early or risk getting ruined, now i have let them go a couple frosts if it got warm during the day.
There are guide lines to growing big plants in michigan annd they are, getting as much sun as you can get during the day so make sure to have a really good spot, next add good soil to ur plot and good fertilizers also i really recomend topping your outdoor plants after about 2 to 3 weeks old... strain has a huge thing to do with it also because if you have good strong genetics your starting off very strong when tryin to grow heavy yeilding buds...and with topping ive grown huge monsters and have had heavy yeilds around a half of a pound, not a monster or a huge yeilder forreal but a handfull of half pound weed plants add up. Also make sure to start them off indoors about 3 weeks to a month before june 1st then plant on june 1st.