Their peat moss imports primarily come from Canada. Some 80 - 90% from what I could find.
There are a few other suppliers that might be able to step up, but the USA seems to be feeling pretty independent these days... I'm not sure how that would go for them
Which is interesting to say... If they did seperate, I highly doubt that they'd be keeping any of the existing healthcare infrastructure.
I don't think the US wants Albertans anyway. I think they just want what they're standing on.