Thatch is a layer of dead and living plant parts that build up on the surface of the soil creating a carpet-like layer that restrict water, nutrients and air circulation from getting to the root zone.
Sod is forced to grow at the sod farm and the process usually causes thatch to exist in new sod when it is purchased and laid. Once sod has been established, we recommend having the lawn aerated to help strengthen the lawn and break through the thatch and allow the roots to go deeper and get a firm hold. If the thatch layer is too thick, a dethatching may be required to make the lawn more manageable. Dethatching consists of using a dethatcher or power raker to lift thatch out of the lawn. The lawn is then raked of the debris and put into brown paper bags which are left at your curbside for organics pick-up. Sometimes it may take a few seasons to remove most of the thatch depending on the lawns condition.
If long grass clippings are allowed to remain on the lawn after it is cut, the buildup of dead plant matter creates thatch. When thatch minimizes the amount of nutrients and water that can penetrate to the root system, your lawn will become unhealthy. As the deeper roots start to move upwards looking for water, they also die and increase the depth of the thatch level. This needs to be removed.
Another reason to dethatch would be in the case where there has been extensive damage from insects, grubs or winterkill. Dethatching or power raking will help prepare the lawn for needed repairs.