What gardening zone are you in? What are your winters like? Is the garage heated? Does it get opened and closed a lot, for vehicle use?

I, myself, am in zone 5b-6, and I keep a large assortment of potted plant material in an unheated, unused garage over winter. So far, this season, I haven't had to bring anything inside out of the elements except my tender, tropical plants that can't take a frost, and those come inside my apartment. But everything else is still outside because the weather hasn't really gotten to the snow/ice/frigid winds point yet.

When it does get nasty outside, and stays that way, and the plants in pots look more like they're dropping into dormancy, I'll bring them all into the empty garage, and I'll group them together in plastic baby pools to keep the pots off the concrete floor. I'll water anything that's completely dry, but everything else will simply get closed inside the dark, unheated garage until spring.

I keep no plants in the garage that is heated, and gets used all the time. The temperature changes too drastically with the door going up and down, everyone using it to enter the inner yard and house, and it's attached to another building that IS heated, so it's not a good option for me to keep any plants in it.

Also, I keep some items that won't fit into the unheated building grouped together outside in a protected area, where the frigid winds won't disturb them. I sometimes pile wood mulch around the grouped pots, and I allow the leaves that drop in fall to collect around them for added protection. Then, I hope Mother Nature will drop a nice insulating blanket of snow on top of everything, which will provide extra protection for everything in pots until such time as it melts in spring.

I do think that how you treat your potted Blueberries will depend greatly upon your zone, and whether or not your garage gets used on a regular basis. If you have a garden shed, that might be a better option... or if you have an area that's shielded from the direction of cold winds, that could be an option, as well. I would still mulch around them, depending on your zone and how cold your winters get.

As for watering all the pots in the unheated, closed garage... over winter, when it snows, I will gather some snow with a snow shovel, and kind of sprinkle it evenly over the potted plants in the pools... or as evenly as I can... to mimic Mother Nature and the amount of moisture that would be provided if those pots were outside, though not to excess. If some are on the drier side, it's okay.

I don't know that I've answered your questions or helped in any way... perhaps others have differing suggestions? I just try to protect anything not planted in the ground from the freezing winds that would most likely kill the roots in anything left out in the open.

Me too. Snow, is how I water plants overwintering in the garage, which is where all my temperate bonsai spend the winter, so there are prolly around 150 plants in the garage now. You don't want the soil to be soaked, just damp enough to keep fine roots from drying out and dying.

Al