I had some heuchera in a pot that recieved no special attention and is comming along fine...
You might want to wait a little on the astilbe- I only have a few in the yard that are showing themselves already, and will have many more comming up soon.
A long while ago there was a long posting about different bushes that survived the winter in pots- but I bet if you searched this forum you could still find it.
I don't know of much more- but I am sure more folks will let you know their successes-

I had a yarrow plant make it through in a pot. Dug it out last summer and had nowhere for it to go so I left it. It's springing back to life like nothing happened. I also have some of those tall orange (native?) daylillies that survived just fine in a pot. It doesn't seem to matter what I do to them - they just don't want to die.. I'm guessing hosta may do well too. Lily of the valley?? I wonder if irises would make it. Their rhizomes are planted at the surface and I can't imagine them knowing the difference if they were in a pot or not..

Daylilies are almost impossible to kill. I'v had some in pots for two winters in a row, with no protection, and they came through perfectly.

With the tarp and the protection, you can probably also try regular lilies.

The upright types of sedums are incredibly hardy. No need to cover or baby them at all.

Remember that in a normal situation, ground temps are moderated, and don't get to the air temp extremes except at the very surface. A foot below, the temperature probably never gets below 20 F. Keeping this in mind, iris with the rhizomes at the surface would have a good chance of suviving in a pot. But Bulbs that are normally down below, like true lilies, maybe not. But really, you never know until you try.

Zones may or may not be helpful determinations. Most places that are cold also tend to have reliable snow cover. Air temps are quite irrelevant in that situation for perennials that die back to the ground each year.

And I would also have to agree that nothing seems to kill a daylily. However, maybe the newer hotsy-totsy ones might be a bit more picky. I don't know.

Rick

I had 3 Buck roses, an Easy Elegance rose and irises and daylilies pull through. They were all in pots with no special care.....go figure.

Hostas should survive fine in pots. A lot of people put the hosta pots in a sheltered area, but I tried with several this past winter and at least a couple are growing at this point. I also have a couple of blueberries that have survived two winters in a large pot. They haven't done much of anything, but they have survived :-) And, I have some little bluestem (grass) in pots that is coming back very nicely.

I have a shallow old farm trough full of about a half dozen different creeping sedums that have made it with no protection for about 3 years now.

I have successfully over wintered William Baffin and John Cabot Roses in pots with little die back for three winters.

I've had red asiatic lillies come through a couple of winters in two big clay pots in the front yard.