Well, they don't really - the trunk is where all the roots are, that's the fibrous stuff you see all over them. I don't think it would be alright in a trough though, too shallow to keep the plant upright, but I did plant one once in a deep stone pot, probably about 16 inches deep by the same across - we wedged the trunk in place just an inch into the compost with large cobbles until it stabilised itself, and it grew very well indeed. I think a heavy pot is probably essential, though the one we planted was already about 3 feet tall...

Thank you Bamboo. Will look out for the right size heavy pot before getting a Tree Fern. Another challenge!

Best to wait till spring before acquiring an expensive Tree Fern anyway - gives you a good five months to find the pot, lol!