Protecting your Tree Fern in Winter
Insulate the top of the tree fern with it's own leaves! To do this, fold the leaves gently into the crown. They will turn brown in the frosts.
Tie the leaves in place with some string.
This should do it! However, for further protection....
Cover the tied leaves with a cotton bag (or sack, for larger tree ferns) which will provide added protection and will hold everything in place.
Adding straw to the bag will provide extra breathable protection. A word of warning - do NOT use material that is non-breathable such as bubble wrap as this will cause your tree fern harm.
Your tree fern should emerge from winter looking in tip top condition.