Good Luck, hope it works.
WoW, you already did 4 of them, where are the first 3 located?
It does look nice & ugly.
FYI, grass shrinks 3-D so a weight compressing the GC will lessen the gaps against the walls. Which is the area the roots will first begin to grow and if compressed after, the roots should easily break.
Here's some photos of what it should look like after a few months.
