What is thatch?
Thatch is a build-up of organic matter which forms a layer under the blades of grass but on top of the soil.
During the warmer seasons of Spring and Summer, the thatch is usually made up of runners, living and dead, as well as other organic matter such as leaves and lawn-clippings. In the cooler seasons, thatch is created from dead and dying organic matter.
Read on for why this can be a problem, and what to do about it.