Lots of ferns are hardy in colder zones! I think the most popular around here is the Ostrich Fern (Matteuccia struthiopteris), it's easy to grow in reasonably moist shade and forms colonies.

Gardens North has a nice selection of northern ferns on their website, I don't think I can post the link to the exact page but go to Catalogue - Retail Area - and on the left column select "ferns". I think they just sell spores which are not instant gratification but maybe you could find a US supplier that sells roots.

Oh yeah, Japanese Painted Ferns are really fancy and popular too, they are kinda iffy here in zone 2/3 but zone 3/4 should be fine for them.

Here is a link that might be useful: Gardens North

I've had a Japanese Painted fern for a few years, and it always comes back. But it just never gets very big at all for me. It maybe gets 3"-4" tall at most. Last year I planted a Maidenhair fern, and it's come back, but it's still very tiny. I'm hoping it'll get bigger eventually(fingers crossed).

Yes, like Gillian said, the Ostrich fern is pretty much bullet proof here. I've got them popping up in the lawn already, but they do look so nice in a big clump. They can get 2' to 3' tall here.

Here's some from Fraser's, in zone 4, I'm sure you could probably push the envelope to zone 5 ferns in a protected area too.

Here is a link that might be useful: Fraser's Thimble Farms

Ostrich fern is very nice, though it does spread by underground rhizomes so just be aware. They survive tough places such as dry soil under the eaves of a house, but usually look haggard if too dry and too much sun. Apparently, the more moisture the bigger the fern. I think it's one of those "grow anywhere" ferns that's tough as nails.

I find my Japanese painted fern comes up quite late - just coming up now. In fact one year I went out and bought a new one, thinking the other one was dead. I agree, slow growing I even amended the soil to try to speed it up.

I always have Hart's tongue fern which seems to do okay in a sheltered spot. Here too, though, it never seems to get very big.

I had Christmas fern for a few years and liked it quite a bit. It sort of reminded me of a Boston fern length and style of foliage, though smaller 12" long fronds.

I tried Cinnamon fern as well but though it survived, it never got very big or impressive.

Laurie, I have always liked the look of Maidenhairs. If I get around to getting some ferns, I would probably try those. I have sooo much shade to work with here.

Sharon, wow Fraser's has a huge selection.

Re ferns for nothern climates. Your zone is the main variable but not the only one. Humidity and night temperatures also make a big difference. Winnipeg, for example, is much better for growing a wide variety of ferns than dry-aired, cool evening Calgary. Other than the Ostrich fern (and a few native alpine ferns) few ferns sold in garden centers 'thrive' in most of southern Alberta or Montana. Many species will survive but that's about it. There are lots of plants other than ferns that can give a cozy woodland feel.

I'm in great falls, near the Missouri river. My ostrich fern has come back, but my japanese painted has not. This year I am adding a variety of ferns to a "rough" area I have, and we'll see! I'm taking hope that the painted fern is just slow