I have access to granite counter tops remnents. One side is polished, the other is rough. I'm going to use these pieces to make a large patio(rough side up) in my back yard. The patio would be roughly 25 feet by 35 feet with some areas scattered around left as soil so I can grow plants (flowers & veggies).

It would be a big job to dig up all the sod. I don't care if the patio is higher than the current sod--sloping is not an issue. Would it work to RoundUp the sod then lay gravel & sand directly on top of the dead sod then lay the granite stones? I'd like the patio to be mostly level but it doesn't have to be perfect. I'm going for an informal/casual look. Also, how deep does the layer of gravel or sand need to be?

Any advice hugely appreciated. Thank you.