I seem to recall seaing this question,but weather it was on hear I don't recall, it seams that it is only the ferns themselfs that need protection as the trunk consist of dead ferns,it is evergreen but considering were it comes from may be a sheet of bubble wrap over it ,because these frost we are having are server,your local gardencenter will have it on a roll at diferent withs,and is the cheapest way,as some one on the site has pointed out, incerdently just in case you don't know it is also known as soft tree fern/man fern/ and tasmanian tree fern, hope this helps have a nice christmas

You can protect the crown with straw Bally or fold the leaves in on themselves so the damp and cold is kept away from the crown where the new leaves will emerge.

You can buy protective fleece from your garden centre and straw from a pet store or farm.
Take a few large fist fulls of straw and push them into the crown of the tree fern where the new fronds are likely to emerge. This is the area that need protection. Push about 50 cm x 50 cm (depending on the size of your fern) into the crown, then cross strips of fleece over the part you have protected and tie them around the trunk.
Do not use bubble wrap. If you get any condensation forming inside the plastic bubble wrap, that will freeze and potentially damage your plant. I only use bubble wrap to protect and wrap up pots.
You can gather the fronds up to a point and tie them aswell - like a wigwam, but if it is a large specimen, the fronds aren't that easy to manipulate. As long as you protect the crown where the new fronds will appear in the Spring, you should be ok.

a thank you from me,to you both, I too have learned aswell.