Hey Tom,
Central MN, eh? What city are you in? I'm staying in Long Prairie right now. I've got some of my original Cold Hardies growing where I planted them nearly 20 years ago. It would be fun to trade visits. I can also show you more non-cold hardy cacti than you've probably ever seen in Minnesota.
Daiv
Extremely Cold Hardy Cacti
We've gotten about 8 inches of snow the last two days, and temperatures have stayed well below freezing... I think this is going to be a good thing for my cacti, if I remember correctly, its the freezing and thawing that usually kills them, not just the freezing. So yeah, here's keeping my fingers crossed that they all make it! As soon as I get a picture of them peeking out of the snow, i'll make sure to post it!