This past winter, my butterfly ginger overwintered in my unheated garage and I was very very worried that it would rot from the severe winter we had. One or 2 of the rhizomes did rot, but the rest remained healthy regardless and when I took them indoors in March, they started to sprout. When they went outside they didn't skip a beat at all and the sprouts continued to grow vigorously. Fast forward 4 months and now I have some blooms forming. It should be in full bloom by mid September so it will be plenty warm enough for it to make healthy blooms. Last year it didn't start blooming until October so I did not get to enjoy the blooms. I am so happy it's blooming early enough for me to really enjoy it still!
Here's a picture of it this afternoon (you can see the bulge in the stamp and the little flag leaf on top). I'm excited! I may one day have the courage to overwinter these outdoors, but I like them too much to even risk losing them.