Its not a matter of finding plain old soil. You arent looking for soil, you are looking for the ingredients to make your own soil. Which you can find in urban areas fairly easy.
1 or 2 of the items you need you can get at home depot or lowes. cant get any more urban than that...
1 or 2 of the items you need you can get at home depot or lowes. cant get any more urban than that...