Lawn Thatch:
What it is and what you need to know about it

Thatch– the build-up of grass roots and organic debris where the grass stems meet the soil.

A soil profile shows a matted cap of thatch.

A thick layer of thatch has accumulated between the grass roots and the soil.

A thin layer of thatch (less than ½” thick) is not a problem but as it gets thicker, it can be a problem for our lawns. Build-up of thatch inhibits water and nutrients from reaching the soil and feeding the roots.

With adjustments to your lawn care maintenance, you can resolve your thatch problem. Here’s why… Thatch is:
1) A result of grass roots growing across the surface of the soil, layering on top of each other, and building up over time; and
2) Dead organic debris that is not being consumed by the soil microbes.

Let’s address grass roots first- In the PNW, our primary grass seed mixes are ryes and fescues. Ryes and fescues are clumping grasses that have the ability, if allowed, to grow roots as deep as 14 feet! That’s right, 14 feet! If your ryes and fescues are growing across the upper soil layer, it’s an indication the soil is compacted and the roots can’t grow where they need to (not a grass problem).

The other grass seed that could be blended with ryes and fescues is Kentucky Bluegrass. Yes, Kentucky Bluegrass is shallow rooted and “rhizomatic” meaning it grows left-to-right and not downward like the clumping grasses of the ryes and fescues. But, if Kentucky Bluegrass is mixed in, it is a tiny percentage of the seed mix, usually not exceeding 15%. Point being, if you have thatch, it is probably not the Kentucky Bluegrass that is causing the build-up.

Dead organic matter is a sign that your soil microbial activity is low. Healthy soils can contain more than 4 billion microbes in a single teaspoon. If you have healthy microbes, they will continually consume the dead organic matter and make it into food available for your lawn to consume.

A dethatch can loosen loads of organic matter in the lawn that was beyond sight.

So much thatch was hiding out of sight. This gas-powered dethatcher is the first step of the solution.

What to do if you have thatch build-up? Roots need to reach into the soil easier, and the microbial activity in the soil needs a good boost. First, the lawn needs a dethatch to prevent problems. Then the lawn needs annual aerating, adding a blend of soil microbes, and compost to feed the microbes. This will allow greater passageways for the roots to find deeper growing conditions. Once this happens, thatch goes away and the roots grow deeper. It is common to find that the lawn will then require less water and fertilizer to maintain a healthy lawn 🙂

Do you have other questions around thatch? Give us a call and discuss how we can solve the problem for you.