Thatch and Mat in Turf Management

Thatch and Mat

To properly manage your turf, one of the key components to keeping it healthy and vibrant is the management of thatch and mat. Understanding what thatch and mat are as well as how they are useful in turf management will help you combat potential problems that often arise. Here we’ll outline methods of controlling thatch and mat to ensure that you’ll have the best quality turf around.

Definition of Thatch and Mat

When we talk about thatch, we’re referring to a layer of partially decomposed organic matter between the green shoot tissue and the soil surface. Let’s break that definition down even further: The partially decomposed organic matter consists of living and dead plant tissue. This can be sloughed roots, horizontal (grass) stems, and mature leaf sheaths and blades. All of this tissue is in process of breaking down or partially decomposed.

Mat is thatch that is partially intermixed with topsoil. This phenomenon occurs when a sand topdressing has been used and thatch is too slow to break down.

Conventional Wisdom

Decomposition of thatch into mat is preferable when it comes to turf management. Mat can hold more water and nutrients, giving it better properties than thatch and making it more beneficial for the health of your turf. Both mat and thatch provide a cushioning layer underneath the turf that helps absorb impact from high traffic areas. It also significantly decreases sports injuries.

Thatch is porous, allowing an exchange of gases between soil and atmosphere. It also protects the growth point of the turf from extreme temperatures, both hot and cold. However, thatch can become excessive— it’s considered this when it’s over half an inch in home lawns. This can be caused by over-watering as well as high nitrogen rates.

Thatch Problems

A high level of thatch can cause a lot of problems in turf management. The amount of water infiltration can be significantly decreased, which could create localized dry spots. These areas can turn brown and threaten the health of the whole turf.

If your turf is in a colder climate, or a climate that is cold for part of the year, high levels of thatch can decrease the tolerance of the turf to cold temperatures instead of protecting the roots. It can also cause a decrease in the effectiveness of pesticides, which can lead to insect problems.

Thatch and Mat Management Studies

There are many studies on the subject of thatch and mat management. The following are six areas in which studies are taking place and what the field’s leading researchers have found on these matters.


Topdressing is a sand or prepared soil mix applied to the surface of the turf for producing a smooth look. A thin, even layer goes on top of the turf and is also supposed to control and manage turf by improving the micro-environment of the turf.  That said, the results of this research are inconsistent. It appears that topdressing alone does not reduce or control the amount of thatch in turf. You’ll need to implement additional tactics to aid your thatch.

Equipment recommendation: The Toro ProPass 200 is used mostly for topdressing greens, and the Toro MH-400 is usually used for fairway topdressing.  Both are available from Kenney Machinery.

Vertical Mowing

Vertical mowing involves using a different kind of mower, or de-thatcher to cut the grass. It is best to do this in a period of active growth. According to the most recent studies, this neither reduced nor prevented accumulation of thatch.

Equipment recommendation: Thatching Reels can be add to any of Toro’s triplexs (greens or tees) and fairway mowers, such as the Reelmaster 5410 units.


Studies have shown routine mowing along with proper care of the turf to be vital to the management of thatch and turf. Don’t neglect the basics of turf care and you’ll be delighted with the results.

Equipment recommendation: Groomers can be adding to any Toro walking greens mowers, fairway mowers, or triplex mowers.

Core Cultivation

Studies have been done that show when four core cultivations or aerations are done per year, there is not an effect on reduction of thatch, however, there was less accumulation than uncored turf.

Equipment recommendation: Toro’s line of popular ProCore units can handle your aerification needs, including the 648, 864, and 1298 units.

Biological Thatch Control Product

There have not been many studies on biological thatch control products, and while it would make turf management easier, in a two-year study on Thatch-X, there was a 12% increase in thatch compared to turf that was not treated with Thatch-X.

Combination Treatments

A combination of core cultivation, vertical mowing, and grooming was the only study that showed true reduction and management of thatch over a two year period. Studying your turf, and doing a combination of treatments to control and manage thatch is the most effective way to find what keeps your turf in top condition.

Control Methods

If you are running into thatch problems, then the turf is out of balance. The best way to figuring out how to fix this is to determine what’s causing the imbalance in your turf. Consider doing any or all of the following options.

Control Option #1: Nitrogen Reduction

Reduce the nitrogen levels in the soil. The easiest (and most efficient) way to do this is to stop putting anything on the turf that adds nitrogen to it.

Control Option #2: Increase pH

Raise the acidic soil pH to a more neutral level. Liming acidic soil is the best method of accomplishing this. Why? Lime is neutral— it will lower the acidity of your soil. However, keep in mind that you should conduct a pH test to see if your soil is actually acidic before you add lime to your soil.

Control Option #3: Deeper Watering

Water your turf less frequently but more deeply. This can be achieved by not watering every day— two or three times a week will be sufficient.

To let the water soak deeper into the ground, do the following: water for 30 minutes, turn off the water and let the water seep into the soil, and then water for another thirty minutes. This trains the roots to go deeper into the soil to get the water.

Control Option #4: Better Drainage

Improve the drainage of your turf by adding holes and putting in a topdressing in areas where drainage is a problem. Adding drainage systems is an option as well although a more costly one.

Control Option #5: Mow at the Proper Height

Proper mowing height is very important. The universal rule is never to remove more than ⅓ of the leaf surface in one mowing.

Control Option #6: Proper Mowing Frequency

Once proper mowing height is established, know that proper mowing frequency is important to keep the ⅓ rule in place. Different times of year will require a different frequency in mowing.

Control Option #7: Core Aeration Redistribution

To further reduce and fix the layer of thatch to a more reasonable depth, consider core aeration redistribution. In late spring and early fall, most turf managers will aerate their turf. The soil cores that come from aeration, can be ground up and redistributed over the turf. This will encourage the decomposition of thatch by using the microorganisms in the soil.

Control Option #8: Carefully Consider Pesticides

Consider the judicious use of pesticides. While you definitely want to avoid an infestation of insects, be sure that the products you are using do not contain anything that might harm the grass, which would cause more thatch buildup issues.