- there are lots of rocks etc? originally I had a rockery all around the borders of the garden but since cutting down a lot of tall conifers there is much more sunlight coming through which has resulted in a mass of overgrown grass all along the borders. I desperately need to know the best way to cut it down bearing in mind these rocks which are a major obstruction as the nylon cutters on the machine I hired (petrol) keep breaking off evertime they hit an obstruction rocks/tree stumps. Any help ideas etc greatly appreciated