The very first garden I made was in an urban backyard in San Francisco. As I began digging, I discovered someone had broken up pavement at some time in the past, and simply left it there where it had been covered by trash and dirt. I womanhandled unknown pounds of slabs of pavement that I would pry up, across the yard and under the house where fortunately there was plenty of open area.
I was young. And the distance was not as far as to that red mum. But I did have to pry each piece out of the ground!
Anyway, I sympathize, but you are going to end up with something gorgeous, I have no doubt!
