Answer: Overwintering perennials in containers at home takes some experimentation and in my experience, some luck. First off, if possible find a protected spot out of the wind. The best method is to bury the containers in the ground to insulate the roots and leave the tops exposed to the weather to go dormant and awaken naturally. Another possibility is to place them in a sheltered spot outdoors and insulate the pots as best you can -- pile mulch around them (but not over the crowns), use bubble wrap, etc. Yet another option is to place them in a cold frame. (If you try this, take steps to exclude rodents.)
The main objection to placing them in a garage is that it is too warm -- they will not go dormant and thus risk problems with over or underwatering, invite rot due to poor air circulation, and so on. If they are frozen, they will not need water. If the soil is not frozen, they will need water but very little since they are not actively growing and transpiring -- this you will have to do on instinct.
Good luck with your perennials!
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