I have to agree with johnf, it's not made for the really tough stuff. I use it on beds that were cultivated the previous season, etc. On ground that is compacted (and I'm on very clay soil) but doesn't have a network of couch grass roots or similar, I shove a fork in and lever the soil every foot or so giving the Mantis something to 'bite', and then it works its wonders. Pricey, but the company offer a year trial so you can send it back if you don't like it. I bet hardly anyone returns it, the engine starts every time, very sweet sounding too.