How convenient it would be if the lawn mower could also trim and edge your lawn. Unfortunately, this is not the case. On the edges of your lawn, next to the driveway and sidewalk, grass eventually grows so that it is lying on top of these areas. Edging will get rid of this grass. An edger’s blades are positioned so that they cut the grass growing past the cement. If you have not used an edger for these spots, there is a good chance that you have grass growing four or five inches over the cement.