Does Your Turf Make the Cut? Managing Thatch Buildup in Turf

Plants and soil are living organic things, and they grow and change in response to their environment. As a result, what worked one season to keep a playing surface durable and aesthetically pleasing might not work the next. The variables for optimal turf growth and health are measured in ranges, not one-size-fits all quantities. The key is to stay flexible and understand all of your options so you can dial in the right balance of additives, fertilizers, and mechanical maintenance.

Thatch is a great example of this process – it’s neither categorically beneficial nor harmful in most settings, and there is a happy middle ground for which to strive. In this blog we’ll look at thatch basics and options for managing it.

What thatch is and why it forms

Turf grasses continually put down new roots, send up new stems and blades, and die back over their life cycle. It happens gradually and we may not notice the individual grass plants we see are changing over time. Evidence of this growth is in the layer of dead and decaying plant parts that settle below the new growth.

This material generally decomposes on its own; however, when the decay process slows down and the material builds up a layer of thatch is created. Thatch is made of the cellulose and lignin components of grass plants along with leaves and organic debris that end up on the turf.

While the build up is the result of a slowed decay process, it usually doesn’t have a single cause. Often it’s the result of a combination of improper soil pH, excessive fertilizers, grass monoculture, and other factors, as described in this article from Penn State Extension.

Benefits and hazards of thatch in turf

How you approach thatch in your turf depends largely on its thickness. Up to about ½ inch of depth is not necessarily harmful. In fact, some benefits include:

• Greater impact absorption when athletes fall on playing fields
• Added durability in heavy traffic areas such as golf courses
• Greater soil insulation and regulation of soil moisture and temperature

Thatch that is more than ½ inch thick can cause problems such as:

• Blocking the flow of water, leading to dry patches and incomplete irrigation
• Poor drainage and absorption of fertilizers and pesticides
• Harboring pests and/or diseases and fungi
• Mower scalping, in which mower wheels sink into the thatch and cut grass too low
• Blocking seeds from the soil, causing new grass to takes root in the thatch layer instead of the nutrient and moisture rich soil