As a knowledgeable and experienced lawn care provider, we are often asked why it is important to aerate a lawn and what benefit does it provide. Now the answer is simple, it helps to deal with compaction, allows a better exchange of oxygen to the roots and allows more water and nutrients into the soil profile. To understand why aeration is important we need to understand some of the issues that compaction brings to lawns and how plants and your lawn truly work.
Understanding Plant Respiration and Lawn Care
One key takeaway from school biology is that animals exhale carbon dioxide, which plants use to produce oxygen. While true, this explanation oversimplifies the process.
In reality, only the green parts of plants use carbon dioxide and release oxygen, and this happens only in the presence of light. The rest of the plant behaves much like animals—it consumes oxygen to break down sugars for energy, releasing carbon dioxide in the process.
This is particularly true for roots. Beneath the soil, grass roots are constantly absorbing oxygen and releasing carbon dioxide as they grow in their quest for water and nutrients.
Fortunately, soil isn’t solid; it contains countless tiny pores that fill with water after rain and then with air as the water drains. This cycle allows stale air to escape and fresh oxygen to enter the soil. However, if the soil remains waterlogged for too long, roots can suffocate and die due to a lack of oxygen.
Grass, especially in lawns, needs to grow steadily to replace the foliage lost during mowing. For this to happen, the roots must continuously expand to access nutrients and water, requiring a constant supply of oxygen. Maintaining airflow to the roots is therefore crucial for a healthy lawn.
The Problem: Why Soil Compaction is Harmful
Now let me explain in more detail why soil compaction is so bad for your lawn. Over time, as we walk, play, and use our lawns, the soil becomes increasingly compacted. This compresses the soil around the roots, making it harder for them to access the oxygen they need to grow.
Compaction limits the flow of oxygen to the roots and prevents carbon dioxide from escaping. Additionally, it hinders water absorption, making it more difficult for the roots to access the moisture they require.
Many people don’t realise that lawns need oxygen. Let’s revisit the science behind how plants work.
The standard teaching is that the green parts of a plant, like the leaves, use carbon dioxide and release oxygen through a process called photosynthesis.
Photosynthesis is how plants harness sunlight to produce glucose from carbon dioxide and water. This glucose is then converted into pyruvate, which releases energy in the form of adenosine triphosphate (ATP) through cellular respiration. Oxygen is also generated during photosynthesis.
This process is powered by chlorophyll, the green pigment in plants. Chlorophyll is a complex molecule that captures sunlight and drives the conversion of light energy into chemical energy. While chlorophyll’s detailed structure is fascinating, we’ll leave the complexities aside for now. If you’re interested in learning more about photosynthesis, the Royal Society of Biology has an excellent resource on the subject.
The Causes of Compaction
Soil compaction occurs gradually through various activities, including:
- Walking on the lawn.
- Garden parties and playtime with children or pets.
- Heavy equipment like wheelbarrows or lawnmowers, especially if left running in one spot.
- Driving vehicles on lawns.
The repeated pressure forces soil particles closer together, reducing pore space. Ideally, soil should have about 50% pore space, with half filled with air and the other half with water. When compaction occurs, water drains more slowly, and air cannot reach the roots. As a result, root growth slows, grass weakens, and bare patches may appear.
Compaction is particularly visible in “desire lines,” the worn paths across lawns caused by frequent foot traffic. These areas remain barren because air can no longer penetrate the compacted soil.
The Solution: Aeration
The simplest way to combat compaction is to loosen the soil. While this is easy in flowerbeds, it’s impractical for lawns. That’s where aeration comes in.
Aeration involves creating small holes in the lawn, ideally removing plugs of soil. This allows the remaining soil to “relax,” reducing compaction and improving airflow, water penetration and nutrient flow. This is even more important if you are having your lawn treated by us or others as it will help minimise the fertiliser being washed away.
Hollow tine aeration
Hollow tine aeration uses a machine or tool with hollow tines to remove small plugs of soil from the lawn. This is our go to for heavily compacted lawns as it provides longer lasting benefits. It is also very helpful when you are trying to incorporate a top dressing into the existing soil profile. The downside is that it leaves cores all over the surface and these need to be cleared away on most lawns we visit in Essex and Suffolk due to the heavy clay soil profile. This tends to make the work more expensive due to the time, effort and waste costs.
Solid tine aeration
Solid tine aeration involves using solid tines or spikes to punch holes into the soil without removing any material. This can be done with handheld tools, petrol powered aerators. This is really good for less compacted soils or for regular maintenance of high traffic lawns. The holes tend to close up more regularly especially in heavier clay soils if wetter weather comes and the soil expands more. There is a risk that this method can compact the soil in the walls of the holes. This can exacerbate the compaction issue you were ultimately trying to reduce.
Slicing/Slit Aeration
Slicing/Slit aerators use rotating blades to cut thin slits into the soil. Unlike solid tine aeration, slicing aeration does not compact the soil further, as it shears through the soil instead of pushing it aside. This method tends to prune the roots of the grass plant the most, stimulating root growth but it does not tend to go as deep as the methods above. It can be of a real benefit on heavy clay soils if drier weather approaches as the clay dries it can fracture deeper into the soil profile. This has the potential to create a pathway for deeper root growth.
To Summarise
Aeration can be carried out manually with a garden for or other manual aerators although it is physically demanding. This would be a suggestion for those small lawns or someone very physically fit who are insistent on the exercise.
Petrol powered machines are available to hire or buy from a number of places. They come in a variety of styles and specification. It may be wise for you to look at hiring one as a community if there are a number of you who wish to aerate your lawns in the local area.
Ideally aeration would get to depths of around 125mm or more to get the most optimum results. Sometimes this is not possible due to the ground conditions. We would always advocate engaging a lawn care specialist like Logical Lawns to carry out aeration for you. We are highly skilled, experienced and trained to ensure this is carried out to the highest standards and in a safe manner.
Aeration is best carried out in Autumn or Spring but can be carried out all year round with care. See a previous blog post about its use during a spring renovation or this post about what other tasks you can carry out on your lawn in spring for that beautiful summer lawn. We really cannot stress enough how beneficial aeration is for your lawn. It is certainly a surefire way to fire up that soil profile to really bring your lawn to life.