I am thinking about planting some plants that aren't hardy in my winters in oversized nursery pots, burying the pots in my garden beds, then digging them up in the fall and putting them in a greenhouse for the winter.

Would that work? If it could work, should I use potting soil or my garden soil? Any advice?

I think it will work. I would use potting soil. Garden soil compacts badly in pots.

I agree with Paul about using the potting mix. But I'm not quite sure why you want to bury the pots?

Dewberry, we here did our Brugmansia that way for several years. It works and I would combine the potting soil and
your garden soil. I would advise to drill holes in the side of the pots so the roots can escape. Best of luck.

Plants that aren't hardy and can so into greenhouse over winter......

Paul2032 said:Plants that aren't hardy and can so into greenhouse over winter......

Paul, I'm not entirely sure this was in reply to my post, but if so - what is the advantage of burying the pots as opposed to just having the plants in pots sitting on top of the ground? And wouldn't drilling holes in the pots to let the roots escape just be more traumatic to the plants when you dig them up?

Sandy.....perhaps Dewberry prefers the look of the plant appearing to grow at ground level and not above . I don't understand the need for the holes. Sorry if my post seemed a little unfriendly. I didn't mean to be...Seems like burying would be a lot of work....especially in my rocky soil.

No need to apologize, Paul - I didn't take your post as unfriendly, just trying to figure out what I'm missing about the reasoning of burying the pots. (Maybe I don't get it because I, too, deal with rocky soil...)

I've done it. We have high winds year round because we're on top of a hill. I partially bury the pots just to keep the wind from tipping them. We also have deer roaming around, and they often will kick over a pot sitting on the ground. Burying them has worked well, and I just leave the holes waiting for the next Spring.

Planting in pots in the ground is usually done to control the spread of potentially invasive plants such as mint, but there's really nothing against using them for moving them during the Winter.
Your biggest problem would be to find sturdy enough containers: the standard plastic container will go to pieces if buried a whole growing season and the less we say about terracotta pots, the better.

I've had excellent results burying pots for summer, clay and plastic. I've done it for 3 reasons, so plants don't tip over during storms, the roots don't get so hot when the sun doesn't shine on the pot, and so they could be easily retrieved to take inside or into greenhouse for winter.

Overall, this has not been as satisfactory as burying plants without pots & digging them back up to save for winter, for several reasons. The pots are so dirty on the outside, and I've ended up having to dig much bigger holes for a few plants to be able to get under the pot to sever the roots that had grown through the drain holes. In those instances, there ended up being more digging than just digging up the plant without the pot.

A few have had potting soil, which did not go well, I assume because of the uneven moisture movement. If you can use some "good dirt" from a garden area, not dry, dusty, lifeless regular dirt from a mowed area, that is what I do because the results are better.

There are no rocks here, so that's not a concern. I wouldn't trust the mere confines of a pot to contain something I was concerned about spreading. I tried that for spider plant and it got away from me anyway.

Some discussions about this
The thread "Winter survivors & plants in ground for summer vacation" in Cactus and Succulents forum
Many pics of this in progress at the time in this discussion: The thread "Shade plants are on summer vacation." in Houseplants forum

ETA: Ground dirt is HEAVY. There's a limit to the size pot you want to fill with this unless you have some very strong helpers.

Yes it will work. The Disney resorts here in Orlando do this with a lot of their smaller tropical plants, especially bromeliads. They don;t do it because of winter but because they replace them so often to keep everything as perfect as possible