Hi,
From seed in Zone7, the fig treelings don't have time to form hardened wood within the first growing season... So except for some sheltered areas ... The winter will toast them like other succulents.
But if you seed them in a pot and keep them inside during the winter, then they stand a chance.
I have two natural seedlings here ( they came alone this Spring ), and I'm still thinking if I should protect them or not ?
Ho well, one 80liters trashcan over them is not that hard to do ...
Will it be enough ? That is the experience for this coming winter.
Would they do it without any protection, could be another experience.
I have a potted seedling started in December 2013, and I have kept it inside during both winters.
I'm still thinking on what to do with it this coming winter of 2015 ... Let it go dormant or keep it growing .
So, even in Zone6, you could raise them... as a green tree ... as a fruiting tree, the answer is still to come for me. But that's the experience and the challenge !