The house we bought years ago was a rental. And the yard reflected that status in the worst way. There was more dirt than grass; it was pitiful. At this stage in the game the only option was to re-sod the whole thing. So that's what we did. A few years pass and life got busy...jobs, spouses, kids, in-laws. So the yard started to look like it did when the house was a rental. We were contemplating re-sodding once again when my wife decided she would try something first and doused the front yard with 5 x's the amount of pre-emergence than was necessary (rookie mistake).