What is lawn thatch and how do I avoid it?

Lawn thatch is composed of a tightly intermingled layer of stems, leaves and grass roots, which accumulates between the vegetation and the soil. Thatch is produced because brasses reproduce through both seed and by growing side shoots. The side shoots help your grass to grow into a thick and healthy turf, but over time some side shoots will die. If your turf becomes too choked by dead shoots, the living grass will struggle to grow, resulting in an unhealthy lawn. Half an inch or so of thatch is beneficial, but excess lawn thatch should be addressed by detatching.

Too much thatch (1 inch or more) increases the turf’s susceptibility to lawn diseases, reduces its tolerance to drought, cold, and heat stress; and hinders the movement of air, water, fertilizers, and nutrients into the soil. In severe cases, the roots of the grass will not grow into the soil but only take root in the thatch layer making the turf susceptible to drought and heat stress.

Avoid the following practices to prevent excessive thatch buildup in your lawn:

• Frequent, shallow watering
• Severe overwatering
• Fertilizing the lawn with fast-release nitrogen
• Waiting too long before mowing so that more than 1/3 of the grassblade length is removed
• Excessive application of herbicides and fungicides
• Unaddressed soil compation: consider annual aeration