I usually just take them and bury them in leaves in the backyard around my shed. It is not the freezing but the freeze, thaw, freeze, thaw... that will kill them so if you can keep them frozen solid until a real thaw that is all you need to keep them alive.

I agree that it's the freeze/thaw cycle which disrupts the roots and also sometimes too little or too much water. Since the pot changes the ability of its soil to "share" water with the surrounding soil, a plant in a pot my end up with standing water if the drain holes have frozen or may be too dry if there hasn't been any precipitation.

As a side note: At least around here, most often the ground isn't really frozen that deep. Under the road, which is kept clear, it freezes quite deep, but anywhere there are plants, leaves, or snow, it is amazing to me how little depth there may be to the frost line.

SO I have to manage Pests( rodents)and moisture and Temp to keep the plants alive over winter.

What do you think of using the baby pool w/holes,gravel,landscape fabric,and "plant" the pots in soil. cover w/ aged shredded leaves and some galvanized hardware cloth..I could tarp it..

I am hoping my hunting cats and my having to mess with it to keep an eye on moisture will be helpful in keeping rodents down. But i am not above using poison if I must. Thanks guys.

I've often wondered if it would be successful to buy the planter pots which are not plastic but are a dirt/paper/cardboard type of material and are meant to decompose easily. I have two right now that I saved from a mum purchase. I've been told to be careful of the drainage issue, and that burying plastic pots in the ground doesn't allow the roots to drain, resulting in a mass plant funeral. I'm considering cutting the entire bottom off of these dirt/paper pots, placing some perennials in them, and digging the pots to normal planting length. Then next spring they will be dug up with plants hopefully intact and ready to go in normal planters...right?