Hi Thisbetty:
I am not sure if you are asking if overwintering iris in the garage means they will be placed in pots or not. Many people including myself have overwinterd potted iris in the garage successfully. I would pot them rather than leave them unpotted. Even if you crowd multi rhizomes into the pots they are better off. That is because covering with sand/soil will help them retain just enough moisture to stay alive.
That being said, I have witnessed the regrowth of median iris which were left over the winter on a shelf in the garage by mistake and planted in the spring, but the survival rate will be better in the pots.
Laetitia

Survival will definately be better in pots. Lots will dry out totally otherwise.
North Carolina...I'd be tempted to pot them and sink the pots along the foundation of a heated building or line them along the foundation and cover with pine boughs.

I overwintered late comers in a cold frame before. I crowded them in pots nearly touching each other. After the first planting soak I didn't water or open the frame for the rest of the winter. A cold frame can be as simple as hay bales making a frame with some old windows from the dump. Mine wasn't much fancier and hay is a good insulator.

Big dealers hold them over in temperature/moisture controled refrigerators. They cull all the rotters like potatoes and apples. Odd are pretty high they get sprayed with antifungals a few times too. The regular iris dealers only dig what is sold or likely to sell shortly.

Thanks so much. I am potting them this afternoon and will store them outside next to the house and under a our wide overhang. Protected by EV shrubs and old juniper fronds/limbs. I do not have a good place for a makeshift cold frame, tho I might be able to rig up something in this location once all are potted and in place.

And I do agree, when I am not procrastinating, that in our zone almost all plants survive better in the soil or potted outside.