Mowing is a weekly, or more frequent, task for maintaining quality lawns, However, more aggressive mechanical cultivation is sometimes necessary to rejuvenate the turf and remove excessive thatch.
Thatch is an accumulation of living and dead leaf and stem parts. It builds up a layer of grass residue just above the soil line and can become a haven for insects and disease as well as interfere with effective rooting, water and nutrient uptake.
A small amount of thatch is common and is actually beneficial in cushioning the turf canopy, conserving soil moisture and reducing soil compaction. When thatch becomes greater than one-inch in depth it should be removed. Special vertical mowers called dethatchers or verticutters are designed to vertically slice through the thatch and dense turf to lift the debris to the turf surface for removal. Homeowner-friendly vertical mowers can be rented from equipment rental stores or larger nursery centers.
Since dethatching does remove living as well as dead plant parts, it should only be performed when the turf is actively growing so it can recover as quickly as possible. A late spring through mid summer timing followed with fertilization and watering would be a good choice. Heavily fertilized bermudagrass and zoysiagrass lawns are most prone to excessive thatch buildup, but St. Augustinegrass and centipede lawns can also develop thatch problems after several years.
Published April 11, 2011
Dr. Wayne Wells is an Extension Professor and Turfgrass Specialist. His mailing address is Department of Plant and Soil Sciences, Mail Stop 9555, Mississippi State, MS 39762. firstname.lastname@example.org