Stephen Henning wrote:
"J. M. Russo" wrote:


My lawn accumulates an excessive amount of thatch. Does
anyone know the cause of this, how to prevent it from happening
and how to get rid of the existing thatch as easily as possible.


These factors increase thatch development in grass by increasing
production of stems, leaf sheaths, and decay-resistant tissue:
1. choosing particularly vigorously growing grass varieties
2. applying excessive amounts of nitrogen, especially in spring
3. mowing infrequently or allowing grass to grow too tall before
mowing
4. growing varieties that are known to produce large amounts of
tough, fibrous tissue
5. compacted soil conditions leading to shallow root development

Other contributing factors are factors that decrease the rate at which
thatch decomposes:
6. acidic soil conditions
7. pesticides that restrict micro-organism or earthworm activity
8. allowing lawns to go dormant

Newer, improved varieties of Kentucky bluegrass that have been developed
for vigorous growth and better recovery on athletic fields and
high-quality home lawns develop thatch more quickly than the less
vigorously growing common types of Kentucky bluegrass.

Ways to prevent thatch include:

Fertilize only enough to maintain the lawn's desired color and growth.
Fall fertilization (mid to late October) is preferred to spring
fertilization because the resulting growth is not as rapid and lush.

Compacted soils and soils with poor drainage tend to accumulate thatch
faster than well-drained soils. Aerification promotes better moisture
and air penetration into compacted soils. It helps establish a deeper
and healthier root system and also stimulates the microbial activity
involved in decomposing the thatch layer. To be effective, the aerifier
must have hollow tines or spoons that bring the cores of soil to the
surface.

Mowing frequency is determined by the growth rate of the grass. If the
desired height is two inches, grass should be cut when it is no more
than three inches tall - regardless of the mower used.

Avoid using pesticides as much as possible. Many pesticides affect the
microbial and earthworm populations that are involved in decomposing the
thatch layer.

Thanks so much for giving me such useful information. I have
done some of the don'ts which from your information I can
understand why my lawn has so much thatch. You all have been so
helpful and I really appreciate your sound advice.