To me, it doesn't seem to safe because of the bugs and bacteria that could be in the grass. Plus, you never know if your snake is slithering right into a spot where a dog marked it, and there possibly could be pesticides in the grass (unlikely, but possible..). I wanted to take my snakes to the part sometimes in the evening when it is not so hot and let them slither around as they please, but just the things I thought of made me think it wasn't such a great idea, though, in many BP pictures I notice people's snakes in the grass and what not so it seems safe, but I'm always thinking of the possibilites that could happen.