Thaks for all the ideas and support! Blueberries require acidic soil, and ours is not even close to acceptable for them, although the 2 that I put in the ground last Spring are actually doing pretty well, without any soil supplements. In order to grow them in the ground here, you are supposed to have to add soil sulphur, wait months, maybe a year, before planting them, then add it occasionally. I've "interviewed" dozens of people over the last year and not one of them has been successful growing blueberries, except the man at the landscape shop. He can grow anything!
Oklahoma ALSO has heat and humidity in the summer that makes it hard to grow blueberries. I got 14 different varities, all chosen to be as close as heat-tolerant as I could find. That still doesn't fix the acidic soil requirement issue, thus the decision to put them in pots---very large pots--on wheels.
I believe I'll "shelter" those little pots a bit as you suggested by just rolling them into the greenhouse. If we have a normal Oklahoma winter, they will get the required number of hours below freezing even in there. Of course then I'll have to water them occasionally, right? I'm not good at that part. Maybe every 2-3 weeks?