In this thread, the hostas have been moved before into an unheated garage to overwinter. It is being asked about moving into an unheated shed.

What I further wish to ask is, if I let my hostas up here get totally dormant, would it break their dormancy if I put them INSIDE MY HEATED CAR for a 2 day (1500 miles) trip south?
Should I put them in the roof top bag and leave them in the dark and cold all the way home? I'm thinking that will be a yes. But how should they be prepared for this journey?

Here is a link that might be useful: Unheated shed, how to store over winter?

What I'd do:

Wait until just before or after first frost to dig & pot the hosta. Use a porous mix to fill in & around the root ball. Move to an unheated shelter to wait for the move. (Any place where they won't get rained on.)

As to how you actually transport them will be weather dependent. If it's unusually warm, I'd forgo the rooftop bag where they'll get heated up by the sun. (Weight on the car top also a concern?) Have on hand some ice, frozen in 1/2 gallon plastic milk jugs to pack in between the potted hosta and tuck a couple of blankets over them to keep them well chilled--if you transport them inside a heated car.

Another thing you might consider doing--before you load the hosta, put down some large pieces of reflective mylar (cheap tanning blankets), load the hosta & cover with more mylar & then cover with blankets. The mylar will work to reflect heat away from the 'package' and help keep the cold in. Might want to insulate underneath the bottom layer of mylar, too, to protect from any heat rising into the car from the exhaust system. Use recycled styrofoam packing or get a sheet of the cheap (white) beadboard from Home Depot or Lowes. Aim for packaging them in a sort of free form ice chest.

Once you're at your destination, transfer to a place in the shade (but not next to any heated structures.) As soon as you can, pop them out of the pots & heel them in somewhere shady (but dry) and maybe consider lightly covering them with something like pine boughs to keep them from getting too wet.

Then maybe the easiest thing to do would be to just leave the MA hosta in MA & replace them with southern grown hosta. Spring comes really early in Alabama so you won't have long to wait!

First frost in MA is around Columbus Day, so you've got over a month between frost and the move. I've linked frost dates in Alabama below. You should be past first frost there by Thanksgiving, unless you are moving to the Gulf Coast (Mobile).

Let them go dormant here. Wait til about Halloween to be sure they are in dormant stage. Then dig them up with as much of the soil on the rootball as you can keep (or carry). Put them in plastic lined boxes for the trip. You won't need to water them. The soil should be moist enough. Label them carefully. If you are using a trailer to move, put them in the trailer. If a car, use the trunk. If you don't have either of those options then put them as far in the back of the vehicle as possible.

When you get to Bama, find an appropriate spot away from a heated structure and in shade, to heel them in. Just put them in the ground, near each other, but not touching. Move them to their permanent spots next Spring when the pips are just coming out of the ground. I'd leave the pots out of the equation completely. I think it needlessly complicates matters.

Steve

Here is a link that might be useful: {{gwi:368669}}

Ok, I am distracted now by the cookout we are going to, just wanted to acknowledge receipt of your contributions to solving this expected problem.

Are any of you familiar with the Cajun card game, bourre (booray)? I'll put the link to the Wiki article below. I mention it in passing, because becoming a proficient grower of hostas might be like playing bourre. Does not discourage me one bit. In fact, it offers a challenge...not only for raising happy plants, but for recognizing one from another as they seem to change with season and with age. La, la, it is a whole new card game I'm playing now. Back later.
Bon appetit, everyone.

Here is a link that might be useful: Wiki discusses BOURRE rules of engagement

I like Steve's idea of eliminating the potting process altogether and using plastic lined boxes. Eliminates a step, saves a lot of labor and the hosta won't mind a bit.