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How to Improve Clay Soil for Lawns

A lawn with clay soil can be problematic but with sufficient research and effort, you will know how to improve clay soil for lawns in no time.

Clay Soil - How to Improve it for Lawns

Homeowners worry that their lawn grass won’t grow well in clay soil. However, there is always a solution to address the soil quality. 


Effects of Clay Soil in Your Lawn

How to Improve Clay Soil

Clay soil is not necessarily bad for lawns. When there is only a slight amount of clay, your soil will not only be fertile but also have better water retention. Thus, the problems only arise when there is an excessive amount of clay.

Clay soil is incredibly dense and it does not drain well. During the hot and dry summer season, it can become extremely hard and compacted.

When it rains or when you water your lawn, puddles will form and the soil will become soggy. Both of these situations lead to the lack of absorbing enough air, water, and nutrients, which further results in plant stress and shallow root growth. 

Worse, the grass becomes too weak to fend off weeds, plant disease, thick layers of thatch, and pest infestations.

Steps on How to Improve Clay Soil

1. Determine the Soil pH

Conducting a soil test

It’s important to know the pH level of your soil. By conducting a soil test, you will know just how fertile the soil in your lawn is. It will identify how much nitrogen, phosphorus, and potassium reside in the soil.

Either buying a soil test kit at your local garden supply center or examining your lawn on your own will work. Likewise, you can fill a soil sample with bits of soil from various areas in your lawn and send it either to a laboratory or to a county extension.

Just wait for the results and you will know whether your soil is more acidic or alkaline than necessary. Also, you will get recommendations on how to adjust the soil pH to encourage robust grass growth.

2. Aerate the Soil

Since clay soil tends to be compact with poor draining, you should aerate it. Aeration will help more water and oxygen to go in the clay soil by breaking it up and removing some plugs of it.

Through aeration, the root systems of your grass can spread properly and establish themselves better in the soil. Ideally, you must aerate clay soil at least two times every year. 

Refer to our in-depth guide on choosing the best aerator for 2023

Aerating helps in improving clay soil

If you don’t want to buy an aerator, you can rent one at a local home improvement store. In addition, you could use spiked boots if you have a small-sized lawn or you only need to aerate a particular patch on your property.

However, the soil shouldn’t be aerated when it is soggy. You should wait for the ground to thaw and to wait for the period of active grass growth.

If you have cool-season grasses such as Kentucky bluegrass and perennial ryegrass, you can aerate the clay soil in early spring or in fall.

For lawns with warm-season grass varieties including centipede grass and Bermuda grass, you should aerate in late spring or at the start of summer.

Check out our definitive guide on how to aerate your lawn for more info. 

3. Use Organic Products to Amend Clay Soil

You can solve compacted clay soil through natural means. One natural product that homeowners trust is Turface. This was initially made to remove compaction in baseball fields, but Turface has proven to also be effective for homeowners.

In fact, many people use it for their nursery gardens, vegetable beds, and container plants. You can blend the Turface into the soil, but you can also broadcast it on the soil surface.

Apart from Turface, you can use products with humic acid. This material comes from organic materials that have undergone decomposition. A known source of humic acid is coal, which can help your lawn in terms of nutrient uptake and water penetration.

Some people recommend using sand to amend clay soil, but this is a risky method. If you use fine sand, the clay soil could become harder and worse for your grass.

The correct way is to use big coarse sand, but spending time and effort to convert a clay soil to a sand-based soil might be too much for you.

Check out our guide for more information about soil amendments.

4. Improve the Drainage in Your Lawn

We know that clay soil drains poorly. You’ll have a soggy lawn during winter and heavy rainfall. Thus, why not create a drainage system yourself?

You just have to ensure the excess and unabsorbed water moves to another area to prevent puddles from appearing. For one, you can install pipes to quickly transport the water away. Similarly, you can create a ditch or a garden bed.

5. Apply Fertilizer

Best fertilizer for clay soil lawn

Clay soil cannot readily absorb water, oxygen, and nutrients. When this happens, the roots of your grass will grow at a shallow point. To prevent this, you need the best fertilizer for clay soil lawn that has all three major nutrients: nitrogen, phosphorus, and potassium.

However, a vegetable or flower fertilizer is not enough, so you must ensure that you are getting a lawn fertilizer. This type of fertilizer contains a significant proportion of nitrogen compared to the other two elements to encourage lush and green grass growth.

For example, a lawn fertilizer with an element ratio of 8-5-5 is high in nitrogen and is ideal for improving clay soil.

Similar to how you aerate the soil, the time for fertilizing depends on the growing season of the grass on your lawn. Cool-season grass have an active growth during spring and at the start of fall.

In contrast, warm-season grass varieties must be fertilized during late spring until late summer. Also, you can look at the recommendations in the soil test results to help you pick the correct lawn fertilizer.

Improving Clay Soil Frequently Asked Questions 

Can I put topsoil over clay soil?

If you’re happy to raise the level of your lawn, you can apply a thick layer of topsoil (minimum 6 inches) after fully aerating your clay soil. Choose a grass type that’s suitable for clay or poorly drained sites, and you’ll have a reasonable surface for grass.

What grass grows best on clay soil?

The best grass type for clay soils is tall fescue or fescue. The deep roots of tall fescue grass are less affected by standing moisture, and in extremely hot summers can even help to hold split clay together, and prevent damage to lawn surfaces.

How do I improve lawn drainage on clay soil?

Aeration is the most important thing to do to any clay soil, whether it’s for lawns or flower beds. If you properly aerate clay soil every few months with lawn rollers or even a garden fork, you can improve drainage and reduce anaerobic problems around the roots of your lawn.

Can you turf over clay soil?

You can lay turf on clay soil, but it's best to cultivate the entire layer of topsoil down to at least 6 inches, and add sandy topsoil before lightly compacting and raking over first.

Turf laid on clay soil can struggle to root as the required daily watering over the first couple of weeks can lead to puddling.

Wrapping Up Our Guide on How to Improve Clay Soil for Lawns

In conclusion, you should not feel discouraged if you have clay soil on your lawn. You can still improve the soil to help your grass get the nutrient it needs for deep root establishment and optimal growth. 

Now you know how to improve clay soil for lawns. We hope that our guide helped you changing your clay soil for the better. If you have any queries, feel free to give us a comment.

how to improve clay soil for lawns

About the Author Ann Katelyn

I'm Ann Katelyn, Creator and Chief Author of Sumo Gardener. Since I was a child I've always been fascinated with plants and gardens, and as an adult this has developed into my most loved hobby. I have dedicated most of my life to gardening and started Sumo Gardener as a way to express my knowledge about gardening with the hope of helping other people's gardens thrive.

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1 comment
Richard says April 9, 2020

Hello Ann, I really enjoyed reading your article about how to improve clay soil for lawns, I found it very helpful. Thank you, Richard

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