Rototiller Rocks . Cover your lawn with 2 inches of fertilizers or composted mulch. 1) would it be bad to use a rototiller if i have some rocks in the soil and a small patch of. MTD Rototiller Saanich, Victoria from www.usedvictoria.com Bilt hard 16 inch 13.5 amp electric tiller cultivator. Cover your lawn with 2 inches of fertilizers or composted mulch. It has a gas fueled 25cc engine which provides some real power.