I am 16 and trying to grow some above average pumpkins this year. The variety I'm planting are Prizewinners and I have one that is 60 inches in circumference and it seems to have stopped growing already.

I live in Colorado and our growing season is far from over and we only just got the pumpkins in the ground the first weekend of June.

Is my pumpkin done growing? And is there any way to lengthen the amount of time that pumpkins are still growing? And finally if the pumpkin is done can I just leave it on the vine until October rolls around? Thanks