For a healthy lawn, you should sharpen your lawnmower blades. Dull blades don�t cut your grass, they tear and damage it. You can use a file or a grinding wheel to sharpen them. You should always remember to remove the blades from the mower. Sharpening the blades while they are still attached to the mower is dangerous. You also need to keep the blades balanced. If your blades are uneven, sharpen the heavier end until the blades are level. Unbalanced blades cut unevenly and put extra wear and tear on the lawnmower. This will eventually damage your lawnmower�s engine.