Step 1 would be to see if a nonporous wood holds up to the vacuum of space with enough durability. The biggest issue would be reclaiming moisture from the wood as it dried rather than losing it to space. Things like corals or molluscs would be too heavy (though that idea spawned a wonderful series of 16 bit side scrolling video games).

Without some sort of easy orbital exit/entry, it's unlikely that being "in space" will be a feasible permanent option.