I have a 10'x25' garden area fenced with a 4'above ground fence in a rural area. I am only around to tend the area on weekends so Mon-Fri the groundhog takes full advantage of my absence. I'm not against sharing, but these guys are destructive. I put a dent in the population with a .22 and trapped in areas where they dug under the fence.

This year I'm going to try burying some chicken wire below the ground, but this is no small task in my area where there's much more rock than soil. 6" would be a very ambitious undertaking.

My other idea is, what if the groundhog can't see the garden? Has anyone tried some kind of a translucent plastic around a fenced garden--out of sight out of mind?

You don't have to dig- as long as it's well covered. They'll try to dig under the fence and hit chicken wire. I haven't had one problem with chucks since I did this (had plenty before!).