What is Thatch? 

Thatch is a spongy layer of partially decomposed organic matter that forms on or just beneath the surface of the soil. 

 

A lawn will contain millions of individual grass plants and these naturally go through a cycle of life and death as new leaves and stems replace old ones. The dead plant matter works its way down to the soil where it will begin to decay. Often the rate of accumulation of this material exceeds the rate at which it can break down and the layer will slowly grow in thickness. Certain grasses such as those in fine grass lawns are particularly prone to laying down thatch and other factors such as dieback from drought or fungal disease, excessive mulching of lawn clippings or overfeeding with nitrogen can also play a part. Different types of plant matter such as moss, tree leaves and pine needles will also contribute to thatch formation. Thatch will be more prone to accumulation on soils that are compacted since these will have a lower oxygen content which limits the density of microscopic organisms that can decompose the thatch.

 

How does thatch affect your lawn?

Thatch acts very much like an organic sponge, it traps moisture and can prevent water from reaching the grass roots thereby weakening the lawn. This damp layer creates a perfect environment for moss to develop, which may then become a self-perpetuating cycle where the moss creates thatch, which weakens the grass allowing more moss, which creates more thatch and so on. This spongy surface layer also acts as a catalyst for fungal disease as it stifles air circulation, locks in moisture and harbours the fungal spores.

 

How do we remove thatch from a lawn?

Thatch is traditionally removed through a process called scarification, where a machine with vertical spinning blades claws the thatch from the soil. Hard raking can achieve the same effect but be warned as it can be very hard work! Another method of reducing thatch in the soil is to apply a biological moss/thatch inhibiting fertiliser, where composting bacteria decompose any organic matter that has built up. Your Hampshire Lawncraft technician will be happy to assess your lawn and guide you as to the scale of thatch in your lawn and the best method for removing it.

 

How can we prevent thatch becoming a problem?

The most important step to reducing thatch build up is to regularly aerate your lawn. This keeps the soil healthy and well oxygenated and allows the soil fauna to go to work decomposing any dead leaf matter. Other helpful measures include ensuring that the lawn is fertilised by an expert so that concentrations of nitrogen appropriate to the lawn and conditions are applied, to prevent the lawn from excessively drying in the summer and to ensure that the lawn is mown regularly so that only fleshy leaf tips are removed and not stalks and stems.