Yellow corydalis returns every season in my pots. I grow hosta in pots but I have to move these to an unheated shed in the winter to avoid freeze and thaw.

Sherry

Right now I have many pots with perennials and Japanese Maples inside an unheated garage. Our climate is more harsh than yours violetsnapdragon (we invariably will see -20 C/-4 F temps each winter). The only potted perennial that I have overwintered in an outdoor pot is clematis arabella (it is so hardy). As an experiment, this past Fall I left out a potted paniculata hydrangea "Flare"....we shall see.

I'm not going to be much help as in my zone, any perennials will winter over in containers....and even some 'annuals'. But as long as you are selecting for winter cold hardiness, you are not restricted as to type of perennial you can grow in containers - ANY can work, if sufficiently cold hardy.

Generally, I do not grow perennials in containers for more than a couple of seasons before either discarding and replacing or moving them into the garden. Like anything else grown in a container, eventually the plants will grow and the roots expand to the point that congestion and crowding will limit healthy growth. And any potting soil will need routine refreshing as well.

Same ^^, though issues with dryness and wetness are more severe in pots, when their roots are mostly slumbering and not transporting great amounts of water.

Right now I have hostas and hakonechloa in pots.

What I find works well is to plant in a plastic nursery pot and slip that inside the ceramic pottery for the season -- otherwise the pottery is beastly to transport to storage for the winter, plus I don't want the pottery cracking from the freeze-thaw of the soil moisture.

I'm experimenting with a couple of fruit trees in pots -- we'll see how that goes.

I've done the bring-it-into-the-garage thing, with mixed results. I think it's a matter of remembering to water them once or twice, but not TOO much. I was kind of shocked this year that the heuchera and Jacob's ladder are sprouting/leafing out this early, but I guess it's true what they say about pots warming up before the ground does. These plants are getting watered when it rains/snows only. True enough--they probably need to be divided or moved to the ground after so many seasons, but I don't know how many that would be. It just seems that these look way better (way sooner) than the stuff I've overwintered in the garage.

As far as freezing/cracking, I finally gave up on pots that have that issue--my back is getting too old to haul them in and out. So, don't judge, but my big pots are frost-resistant resin/plastic and they are holding up, so far.

Potted perennials that do well in my zone 5b are: sedums (all kinds small and tall), yarrow (pink and yellow), dianthus, creeping phlox, blue fescue grass. I'm trying a few new things this year, including a small dogwood shrub and a different ornamental grass. I can update you in a few weeks.

So far, it looks like the other ornamental grass I tried may not have made it in the container garden. But I can confirm that hardy geranium (aka cranesbill) did.

It's way to early to make a call on ornamental grass -- the warm-season ones won't start waking up for at least another month up here.

Good to know, mxk3! Thanks. I won't give up on it just yet. I did give it a haircut yesterday when I was cleaning up containers.