De-thatching advice

[Chas Hurst]

Last fall I killed, roto-tilled and reseeded my lawn. The new lawn is very nice but has considerable thatch. Is thatch a problem? If so, should I de-thatch with a machine? The lawn is in SE PA.

[Timothy]

Good day Chas. What do you consider thatch..? What is it that your seeing in your lawn that gives you the impression that it's thatch. I'm asking because this due to the fact that you did a complete re-do of your lawn and you shouldn't have that much thatch.

Thatch is a normal and necessary thing to have in your lawn. A normal and healthy lawn can with stand a half inch or so of thatch. The thatch helps to maintain moisture levels, retain fertilizer and slowly breaks down adding orgainic matter to the lawn area.

What causes thatch..? Over-fertilization, frequent and shallow watering, overly acid soil, water logged soil and inconsistant mowing hights.

Over-fertilization: Nitrogen will create that lush green growth that lawn owners lust after but too much will create grass blades that grow quickly and weakly. The grass plants will develop large/long sheafs (stocks) that will look brown.

Frequent and shallow watering: This can cause thatch due to the root systems being close to the soil surface.

Overly acid soil or water logged soil: These issues will inhibit soil micoorganism from breaking down the thatch hence the build up of thatch will go unchecked.

Inconsistant mowing hights: This is one of the more common reasons for thatch build up. Folks will let the lawn get long and then mow it short and do this on a regular basis. When the grass is mowed short, the living tisses is cut off and a dead stock (sheaf) is left.

Thatch becomes a problem when water and air cannot reach the soil. This will kill the lawn because the water will run off or the lawn smothers without the air.

Should you thatch..? When you water, does the water drain well? Does the lawn area have a 'springy' feel to it when you walk on it? Does the lawn otherwise look healthy?

I would suggest that you aerate the lawn before you consider thatching. Aeration will punch holes into the thatch (and your lawn) and help the water get to the soil (if it's a problem) and restart the micoorganism activity.

[Chas Hurst]

The lawn has brown blades of grass, somewhat matted down, but apparent throughout. The lawn appears, for the most part, healthy.

We have had, until very recently, rainfall sufficient for the grass to grow at a rate requiring mowing every 3-4 days. I mow at about 2 1/2" and use a bagger.

The lawn does have a "springiness" and does look otherwise healthy.

Chas Hurst

[Ulrich M. Reich]

Excellent advice....