Sorry a little late to the conversation here! I had slightly shorte (6/5') tree ferns last year. To start them i didnt do any of the pre soaking i potted up first to allow them to gain moisture from below. they were outside and sheltered but allowed to get direct sunlight for warmth. Every 2nd day i misted focusing on the crown and protected with fleece when frosts threatened. Once growth started i started firtilization with a mild to weak seaweed solution and they sprouted like billio.
Mine are now all planted in the ground (i have a 3rd tiny one) and altough i loose fronds in the winter (which are bent over the crown to protect further and fleece wrapped) they have grown back stronger each year.
The only thing i would say that possibly differs from other posters here is that i have quite a protected enviroment in my garden with a wood to the back and a disused railway to the side both of which offer wind protection and create a warmer microclimate in the back
hope this helps