I have one hen hatched early summer '18 in my flock and last winter it was in the single digits 0 - 10 F, highs in the day of 40's - 50's, typical winter here, she did just fine. I got her when I ordered 8 different breeds of day old chicks. Love her to pieces, she free ranges (as all of mine do) all day and they are in a coop at night, not heated. She was the first of the 8 pullets to lay (June chick, began laying in January) and she was the first to molt this fall. She is completely done molting and her comb is starting to turn red, so I expect her first post-molt egg in January again! Very hardy, but not made for the cold. Let us know how yours do, or do you have them yet?