Verticutting, or vertical mowing, removes thatch buildup in the lawn so turf can breathe easy, better absorb nutrients, and soak in much-needed moisture. Thatch is a layer of dead stems and roots that forms between the grass and soil. It isn’t all bad. Small amounts can actually reduce compaction in high-traffic commercial areas. But when thatch exceeds a half-inch, all that biomass starts eating up the good stuff that belongs to your turf: air, water and food. Plus, insects and disease fester in thatch—more bad news.