I love this flow chart from Auburn Agriculture. Intellectually, I know that most of the time, my horses could live just fine without their blankets. After all, they have access to shelter, I haven’t clipped them yet this year, and we feed plenty of hay. On dry nights, without wind, they would probably be just find. There’s one old horse at our barn who never has a blanket. He’s about 29 and he’s survived just fine.

Emotionally, I feel like blanketing keeps them cozy. I try not to over blanket — there’s no point in making them too warm — but when my fingers are going white from the cold, I like them to have a layer of warmth.
Of course, it may also be that because my fingers are numb, I don’t want to take the blankets on/off three horses while standing in the dark, ankle deep in mud. Yup, that’s probably the real reason. It’s just easier to leave them with a mid-weight blanket on!
What do you do? Blanket or no blanket? Are your horses hardy enough to brave the winters of Canada (Zelda’s former owner reminds me she grew up in Canada, blanketless, and managed to survive) or do your horses get sheets the first time it dips below 50 degrees?