This corner didn't kill any plants... it was my "utility" corner with my auto gate box, water tap, hose etc. But it was the lowest corner of my (sloping) garden, and after digging up my 1st corner (in Garden Makeover - Part 2) I had to check how bad things were here. After all, the grass was almost perpetually wet here. It would squish underfoot everytime I turn on the tap.
I discovered more concrete, more cement wash, a whole layer of anaerobic mud (which smelled really bad), the concrete base that holds up my walls, pvc piping that carried my phone line, scv cable etc, a metal "box" that houses more utility cabling, and a lot of water.
A lot, a lot of water.