LAWN THATCH

The origins of thatch...
The first seven years with a new home lawn has been called the "Honeymoon" period. Much of the reason is due to the absence of a harmful thatch layer over 1/2-inch thick. Up to 1/2-inch of thatch is considered alright, with minimal thatch even being beneficial. However, when thatch exceeds 1/2-inch in depth, problems begin to occur.

One of the main contributors to thatch development is heavy nitrogen fertilization. Some varieties of grass, such as Kentucky bluegrass, tend to produce thatch due to the growth habit of their roots. Heavy clay soil can also contribute to rooting on the lawn surface instead of into the soil below. Aerating a lawn annually helps to combat this situation as well as thatch build-up.

Thick thatch layer

A thick thatch layer on this lawn
made an ideal home for
destructive grubs!

Mulching clippings will not contribute to thatch in normal situations, where there isn't already a thatch problem already. In heavily thatched lawns it will be beneficial to bag clippings, since they are less likely to reach the soil surface where they can breakdown naturally.

AN OUNCE OF PREVENTION

To prevent future problems with thatch, there are several measures which can be practiced annually, preferably in the early fall (September):

Core aeration done once or twice annually, involves "plugging" the lawn with a "hollow-spoon" aerator
Dethatching once every year or two, involves mechanically removing some of the dead debris from the lawn surface
Proper soil pH, usually maintained by liming every 3 to 5 years, will encourage the natural breakdown of thatch

In cases where thatch build-up has exceeded 1-inch, we recommend stripping the lawn with a sod-cutter and starting a new lawn. At this level of thatch, it will take several years to reduce the thatch to an acceptable level, and the cost in the long run will be close to the same. Seeding a new lawn also allows for the introduction of improved turfgrass varieties which weren't available 25 years ago.

Sod cutter

Sod-cutter set for 18-inch widths

Sod stripping in progress

Sod stripping in progress
Fall 1999

More lawn pages: