Just wondering what standard rule of thumb is for landscaping rock depth. We are going to be using 3/4" river rock and since we are moving the rock ourselves, I'd like to spread it as thin as possible, but not be overly skimpy. Basically we are using it as filler in the very back of a planting bed that gets extremely wet - it is a drainage easement. So what do y'all recommend - 1", 2", 3" depth?