Tree ferns
The filigree elegance of a fern with the presence of a tree. Awesome. Some people say that the provenance is everything, some people say it makes not a jot of difference and I can't make up my mind. All I know for sure is that I have owned a Dicksonia antarctica from the Otway region for 6 years, have never given it any protection other than the leaves that fall into the crown and it has been fine having been defoliated a couple of years ago at -7°C. The three main requirements for growing treeferns are WATER, then WATER and finally WATER, especially in our dry old neck of the woods - they come from regions that get 6 x our Essex rainfall. Next important - shelter from wind. Next important - shade. Next important - overhead shelter such as a tree canopy. They will grow in sun, grow in the wind, and grow without shelter even if they don't look their best. One thing is certain, though, and that is without large amounts of water they will die.
I am actually going to cop out completely here. For cyathea, dicksonia and todea, plus full cultural notes, I will link to Ian Barclay's magnificent and comprehensive Cold Hardy Treefern Pages, which covers everything you would need to know. I will add just one or two notes if I have anything to add.
BLECHNUM
discolor
gibbum
nudum
CYATHEA
australis
brownii
cooperi
cunninghamiana
dealbata
dregei
inciso-serrata
lepifera
lunulata
medullaris
milnei
smithii
tomentossisima
DICKSONIA
antarctica
fibrosa
sellowiana
squarrosa
youngiana
TODEA
barbara