What is Thatch?

Thatch is a loose, intermingled layer of organic material that develops between the soil surface, and the vegetation. Thatch buildup begins when your lawn produces organic debris (grass clippings, stems, etc.) faster than it can decompose.

Depending on the amount of thatch present, it may have either a positive or a negative impact on your lawn. For example, a thin layer of thatch (1/2″ or less) provides insulation against extreme temperature fluctuations and varying soil moisture. Lawns with a thicker thatch layer are susceptible to desiccation of root systems due to heat and drought due to the layer of thatch heating up and drying out; thatch layers may also hold excess moisture during rainfalls, resulting in reduced oxygen to roots. Excess thatch can also increase the possibility of pest problems by providing a habitat for large quantities of disease-carrying organisms and insects.

Preventing Thatch

Preventing thatch buildup requires attention to several details about your lawn’s character; grass species, soil pH, lawn maintenance schedule, etc.

Core Aeration

This is an important preventative measure for thatch buildup. Regular core aeration alleviates soil compaction and improves air movement into the soil – this is important to increase microbial activity; organisms that are responsible for breaking down organic material.


Bio-Logic’s 100% organic fertilizer program promotes a healthy plant growth, but also helps to develop a healthy soil. Healthy plant clippings, in turn, create a healthy mulch for your lawn with help from the microbial populations in the soil.

Soil pH Tests

Periodic soil tests help to monitor nutrient and pH levels. Bio-Logic will offer a free soil test with the purchase of our Base Program. Based on the result of the soil test, we can offer recommendations for getting your soil to the optimal level. For more information, see Lime Applications.

Removing Thatch

In cases where thatch layers reach an inch or thicker, preventative controls are no longer as successful. As such, thatch must be physically removed. This is done by vertical mowers with blades that are perpendicular to the lawn surface. As the mower moves over the surface, the vertical blades slice into the thatch layer. Thatch should not be removed when the lawn is weak, or if it is under stress due to heat or drought. This creates the possibility of injury, and reduces recovery potential. Dethatching is typically performed during cooler temperatures – early spring, late summer and early fall. During these times, additional lawn care practices can be done in conjunction with dethatching: core aeration, organic fertilizing, dormant overseeding, weed control, etc.

Does My Lawn Need Dethatching?

Here are a few tests that you can do to help determine if your lawn needs dethatching:

  • Feel the Lawn
    Is your lawn bouncy, spongy or springy underfoot? If so, there is a chance the layer of thatch is too thick
  • Inspect the Lawn
    Examine your lawn closely. Can you see soil between blades of grass? If not, can you easily puncture through the thatch layer that is visible? If you do not see soil, and cannot easily puncture through to the soil, dethatching may be necessary
  • Measure the Thatch Layer
    Excavate a portion of soil using a spade or gardening trowel roughly 3 inches deep. Alternatively, you can pry up a small section of turf. Look for the thatch layer directly between the soil and plant growth and measure it; if the thatch layer is thicker than 3/4″, dethatching should be the next step
Service Areas
York Region
Service Areas
Durham Region
Get In Touch

We would love to chat, listen to your needs and tell you all about our professional lawn care and gardening services!

Want $25 in Bio-Bucks?

Sign up for our newsletter, and receive $25 in Bio-Bucks for your next purchase from Bio-Logic or Illuminations