Dammit, if you at least have the option of growing things in pots then go for it. I have a gravelly area with a few very boring green things around it, in which neighbourhood brats play for hours on end, screaming at the tops of their little voices. I've vaguely contemplated planting something, but I think it's too dark for anything to grow (it's the corner between two streets that go up to the fourth floor, and on the other sides there are delightful university buildings that go up to the thirteenth), plus I doubt there's any real soil under there.