Lawn Thatching

What is thatch and how to prevent it in your lawn?

Grass thatch is a tightly intermingled organic layer of dead and living shoots, stems, and roots that accumulate just above the soil surface of your yard.

It's not necessarily grass clippings even though they may contribute to the problem. Thatch accumulation is due to either over-fertilization, over-watering, and/or soil compaction of the lawn.

While a small amount of it is helpful as it helps regulate soil temperature and moisture of the lawn, too much of it interferes with air and water intake and makes proper lawn care difficult.

Too much of it can also reduce how effective fertilizers and pesticides are and increase disease and insect activity. Eventually, roots may start growing in the thatch, and since it does not hold much water, the lawn can become victim of drought.

Many people interested in lawn care aren't familiar with thatching; or know why they might need to be concerned. Thatch is a layer of living and dead organic matter that accumulates on top of the soil, just beneath the grass.

Thatch is mostly made up of living turfgrass stems and roots, and decaying or dead grass and debris in the process of breaking down and becoming part of the soil. Grass continually renews itself and thatch is a normal part of that renewal process. It's not unusual for a yard to have thatch. The older and more established a lawn is, the more likely it has thatch to some degree. Some thatching can be beneficial as it insulates lawn roots from extreme cold in winter and excessive moisture loss in summer. But sometimes, due to environmental factors or improper lawn care practices, thatch accumulates faster than the dead matter can breakdown and become soil. Excessive thatch (more than 1/2 inch thick) encourages pests and disease, discourages healthy grass rooting, and can interfere with some lawn care practices.

Lawn care can have a major impact on thatching. For example, excessive nitrogen fertilizer applications or frequent overwatering can contribute to thatch, because they cause the lawn to grow too fast. Some people mistakenly blame grass clippings dropped on the lawn after mowing as a cause of thatch buildup. Clippings are very high in water content and breakdown rapidly when returned to lawns after mowing, actually helping reduce thatch. This assumes lawns are properly mowed on a regular basis (not removing more than one-third of the leaf blade at a time) at the correct height.