Try the HARVEST FORUM as I am sure that someone who posts there can help

I suspect unless you pickle them they are not acidic enought to safely home can.

Why not try freezing?

While it's true that non-acidic foods aren't safe to home-can by the water-bath method, they *can* be safely canned in a pressure canner. The Ball Blue Book doesn't list anything under either "ferns" or "fiddleheads," however, so I can't help you with any of the details. You could perhaps extrapolate from the Blue Book directions for something vaguely similar, like asparagus (which is also non-acidic), but canning can be a tricky business, and hard to guess at.

KSRogers and Judy_B had a couple of good ideas. Freezing would probably give better results than canning, but maybe you don't have the freezer space. I did find an internet article (see link below) that mentions canning both ostrich and bracken fiddleheads. It may be possible to contact the author through the web site. He also mentions preserving fiddleheads by dehydrating.

Here is a link that might be useful: Fiddlehead Ferns by Sam Thayer

Ostrich fern is safe to eat but bracken fern is carcingenic and should not be eaten. In the Orient, where bracken fern is eaten, it is blamed for stomach cancer.

Here is a link that might be useful: Bracken Fern Cancer

The above link "Fiddlehead Ferns by Sam Thayer" should be pretty much completely disregarded. This gentleman is doing a supreme misservice to the public with his supposedly "expert" info. I adore fiddleheads & buy them at spring markets as soon as they're available. But eat them COOKED, & only COOKED - & the only variety available & the only one that you should be eating is the Ostrich fern. Not only are no others guaranteed safe to eat, but it has been well-known for quite a long time now that fiddleheads should NEVER EVER be consumed raw.

If you do an internet search on them, both scientific as well as online purveyors of them will tell you this.

While there used to be a company that actually sold them canned/tinned, they gave up the ghost a long time ago, mostly I suspect to quality. Canned fiddleheads are nothing compared to properly frozen ones, which you can obtain year-round on the internet. I believe the online company "Earthly Delights" (among others) carries them frozen. That said, if you are harvesting your own & are sure they are Ostrich ferns, all you need do is blanch them for a minute or two, drain, dry, & pack into freezer bags.