RE: prolifs in the winter, in the north
Dormant daylilies will go dormant - light conditions
So many aren't dying, they are just going dormant.
If a plant is too small and put outside or planted outside, they will freeze/thaw and die.
If you do want to put them outside, I am one who advocates turning the pots on the sides. You don't want water in the pot, freezing the crown. Or freeze thaw, freeze again, with wet crowns and roots.
Most all plants that I turn on their sides, or put under a bench with a tarp over them, do fine. But they are not prolifs. Prolifs, I have kept inside. I don't have rust. And would water spray off aphids. I have been successful, and I have been not successful. But hey, they are free plants!
In the south, I hear they that you can just put them directly in the ground. My roots don't start growing until Oct/Nov!