Really Cyathea cooperi. About as fast growing and tough a tree fern in the world. Maybe not THE hardiest-but close and with all other traits surpass the others. Helps too it is easily propagated..a nurserymans dream tree fern!
Mine survives typical winters in 8b - 9a. Keep it faily dry and provide good protection for the tip of the crown. Do not allow water into the crown during the winter. I slide a large cardboard bow over mine. Shovel it full of dry leaves, then cover the whole thing with a Big trashbag, but allow for some air circulation. I normally have to trim the fronds quite a bit. I start watering with high pottasium fertilizer in the fall, and cover it just before the first frost.
