Aeration vs. Dethatching: The Differences, Explained

Many common lawn care concerns are easy to spot: lawn disease, for example, may cause your lawn to discolor or wilt, and pest damage is typically fairly obvious up close. Thatch is an exception to the rule. In fact, to the untrained eye, thatch may not be visible at all. But left unchecked, this lawn concern can cause noticeable — and, in some cases, persistent — lawn care issues down the road. That’s where dethatching and aeration come into play. Both of these practices can help break up thatch and help promote a fuller, thicker turf. But how do you know when to dethatch your lawn versus aerate it? And when should you remove thatch versus keep it? We’ll answer your most pressing thatch-related questions in this guide to dethatching vs. aeration.

First, let’s rewind a bit and review what thatch actually is. Put simply, thatch is a brown, spongy organic layer of sloughed and partially decomposed roots and stems that accumulates at the soil surface. On its own, thatch isn’t a problem: A thin layer of thatch can benefit your lawn’s overall health. 

The problems begin when too much thatch accumulates. Generally, a half-inch in depth is considered problematic. At this thickness, the densely packed debris begins to limit how much air, water and nutrients can reach your grass’ roots, which can result in poor growth. 

Keep in mind that not all turfgrass species produce large amounts of thatch. Thatch can be a concern for species that produce underground stems or matter that doesn’t break down easily, such as Kentucky bluegrass, bermudagrass or zoysiagrass. If your lawn consists of one of these species, keep an eye out for thatch. A lawn with excessive thatch may feel spongy under your feet or stay unusually wet after the rest of the lawn has dried. 

Both aeration (which TruGreen® offers) and dethatching can help remove excess thatch and promote a fuller, healthier lawn. But these two lawn care practices have a few key differences, including when they should be done and their benefits. Keep reading to learn more.

Lawn aeration is a practice in which a machine (called an aerator) removes small, circular cores from your lawn. These cores consist of thatch and compacted soil. The plugs of soil are then left on your lawn, where they break down naturally. This process encourages microbial growth, which helps to break down thatch. 

Dethatching a lawn involves using an electric rake or a specialized tool called a dethatcher to physically remove thatch. It’s typically only performed on cool-season lawns, as warm-season grasses have woodier stems that can clog the machinery.

Another difference is that the best time to dethatch a lawn is in the spring, unlike aeration, in which timing varies depending on your grass type.

In addition to helping decrease thatch, lawn aeration has the following benefits: 

• Breaks up dense, compacted soil
• Increases the availability of air, nutrients and water to grass roots
• Stimulates root development and growth
• Helps build a thicker, more resilient lawn
• Improves the efficacy of overseeding
• Reduces water runoff and puddling

The main benefit of dethatching is that it removes large accumulations of thatch quickly. This, in turn, helps improve water penetration into the soil and improves grass health.

However, while dethatching removes thatch, it does not relieve soil compaction or improve soil conditions like aeration does. Another thing to keep in mind is that dethatching, generally speaking, is not a professional service. You can rent a dethatcher at many garden stores, but you’ll have to put in the elbow grease yourself.

As both aeration and dethatching will help lessen thatch, it can be challenging to determine which option is better for your needs. Dethatching may suffice if your only concern is quickly minimizing a thick thatch layer on a cool-season lawn. But if you’re only dealing with thatch (up to a half-inch thick), have compacted soil (a common concern after a season of heavy foot traffic) or plan to overseed your lawn, aeration may be a better bet.

Dethatching is, by all accounts, a drastic measure: it’s generally reserved for extreme thatch accumulation and, as such, isn’t usually needed annually. Aeration, on the other hand, should be performed once per year — though if your soil is highly compacted, multiple treatments may be performed.