After a while, tree ferns can become independent in winter. Once they have had a chance to overwinter and harden, they will absorb the sub-zero temperatures as you would for a tree. But before that, there are some simple steps you need to take to protect this ancient wonder. You can easily find the best cyathea cooperi via https://www.plantvine.com/product/cyathea-cooperi-australian-tree-fern/.
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Protect the crown
The crown is the key to the large leaves, and it is the part that will stifle the growth of your tree fern if damaged. Luckily, in the fall, the solution is all around you – the leaves. Stuff a few handfuls around the base of the leaves protruding from the crown and they provide a nice layer of insulation on the coldest winter nights.
If the leaves are somehow unavailable – you've probably cleaned them all – the straw mat you have for your hamster will do that too.
If there are no edges, then you can do anything with extra insulation and fluff, but you don't have to cut sheets just for this. They will likely turn black if damaged by frost and ice, but you can wait until that happens before pruning them back.
If you don't have garden feathers, you can wrap them around the trunk/stem. You can use whatever you like to keep the insulation in place. Again, use fall leaves, but you'll need something like corrugated cardboard or chicken wire to keep the leaves where you want them. It's like filling socks with paper for a Halloween costume.