Building raised bed against a fence?
My husband and I have a very small backyard in an urban area, and we decided to build a raised garden bed along the fence using concrete pavers. We've researched tips on building this type of raised beds, but we still aren't sure how to protect the fence (which is ~5 months old, cedar, untreated wood). We'd like to grow produce in the bed, so I am concerned with any solution that would involve potential toxins leaching into the soil.
Ideas we've considered:
-Protecting the fence with some sort of plastic? My concern is that might not allow the fence to breathe.
-Building a protective "wall" against the fence out of 4"-wide cinder blocks.
-Covering fence with cement blue board.
-Building a "buffer" against the fence with treated wood, and then maybe covering that wood with plastic to prevent chemicals from leaching into the soil? Or maybe covering fence with some extra cedar boards for protection.
-Installing some kind of french drain?
Also, I read on another forum that someone suggested laying a perforated pipe surrounded by crushed stone along the bottom of the fence to improve drainage. Is this recommended? Where would the pipe drain to?'
Thanks in advance!