@ossobuco,
Adds, on black plastic, it is famous for destruction of the 'animal' life of the soil by burning. Rocks are pretty good for that too, at least in some areas - talk about heat sinks. I suppose plastic use can differ by region (trying to imagine this, and green witch doesn't use it either), but I don't know any professional who used it in southern california when I was practicing.
Meantime, I live in a black plastic housing tract.. and there are some points of view toward having it with our deep burrowing aggressive plants that fly in.