theres no straight answer to that, im sure if you use some dish soap you will be fine, and if the grass turns yellow stop using it, ive used a lot of dish soap on my turf, and consoquently on the grass, in fact now that i think about it i think one time i just sprayed water and than threw an entire bottle of dawn onto the little slope behind my house, and i dont recall any grass dying... so no, i dont think so