A Verticut unit is one with fixed knife blades that will slice through the thatch and into the soil. Spacing is important here, too close like one inch and it will dethatch the lawn. 1.5 to 2 inch spacing is ideal. A verticut can be used to stir seed into the top layer of the mineral soil layer under the thatch layer. Thus the term Verticut / slice seed or slit seed. A dethatcher is a machine designed to "remove thatch" and not cut into the soil. Blades a usually flail or springs that give way rather than cut into. They are closer often .50 inch apart. The hammer on the thatch layer (organic layer) to loosen it and pull it loose so it can be removed. Dethathing will also do a great deal of damage to the growing plants unlike the minimal damage done by verticutting.
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