Thatch is a thick layer of grass stems, clippings, roots, and other debris that has gathered up over time and decomposed on top of the growing grass in your yard. This can be very harmful to your lawn because it accumulates over your soil right below the grass line and typically can not be seen, allowing it to block any water or nutrients to get to the roots of the new grass that is trying to grow.
The cause of thatch buildup can be based on several different factors. Poorly aerated soil, an excessive amount of nitrogen, or infrequent mowing can cause thatch to be a likely problem in your front or back lawn. A layer of thatch is the perfect place for insects and pathogens to accumulate while it also repels water from entering the soil which will eventually lead to hydrophobic soil conditions. This means that more maintenance will be required in order for your lawn to get back to looking its best once again.