Gardening Advice

How to Improve Clay Soil for the Garden & Lawn

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Clay soil can be both a blessing and a curse. The waterlogging problem can make gardening and lawn maintenance feel like an impossible mission. However, like every other type of soil, clay also has its pros. Especially if you are looking for good potting soil for growing herbs and other plants indoors, then clay will work just fine.

However, if you are stuck with heavy clay soil in your backyard, but you still want to turn it into a workable material, then don’t fret. There are ways you can break it down and significantly improve its structure for planting veggies or just growing a lush lawn. We have them listed right below!

Table of Contents:

What is clay soil made of?

It’s not that clay soil is poor in nutrition; in fact, it is richer than most other soils. Although the fine particles give it a smooth structure, they are also the source of all problems. They stop the even distribution of air and water to the root system of the plants.

They also stop the water from draining properly, hence the frequent waterlogging problem, and can preserve it for weeks at a time. This has a negative effect on a lot of plants, especially those that cannot tolerate excessive moisture. Their root systems start to rot and soon the whole plant is dead.

Clay soil is also prone to compaction. The ground can become so hard that it cracks if exposed to the scorching summer sun for long. In other words, fine-grained clay soil causes many problems for gardeners and lawn owners in Australia.

This is especially true for people living in the western parts, where the soil combines layers of sandy loam but also sandy clay, with the latter being the bottom layer. Of course, clay in different percentages can be found in other Australian states’ soil structure. One of the important things to remember, though, is that if clay makes up more than half of the soil’s composition, then you are dealing with tough heavy clay. Testing of a sample can reveal the structure of your specific soil type.

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What can you do to effectively improve clay soil?

Now that you know more about the structure of this type of soil and its problems, it is time to find a workable and, if possible, quick solution. Basically, there are two main ways to break down clay soil – either with tools or by adding different materials to change its structure. Just to make things easier, we’ve also provided a few other alternatives to help you cope with problematic clay soil if things don’t work out as planned. Read the details below!

Gypsum for clay soil

Gypsum is often used on heavy clay soil in particular, as it breaks down the compacted matter. Unlike sand, which can actually harden clay, gypsum makes it crumbly. The latter also helps lower the levels of salt and enriches the soil with calcium.

However, there are two downsides to this method you need to keep in mind before going forward. The first one is the limited effect, which extends to just a couple of months, after which you will have to repeat the procedure or face the clay soil’s waterlogging issues all over again. The second is the delayed result, as gypsum takes at least a few months to break down clay soil and make it workable.

Regardless, this is still an effective and often preferred method to improve clay soil and its draining qualities.

How to apply gypsum on clay soil:

Calculate how much you will need. On average, you can apply around 1kg of powdered gypsum per square metre.


Dig at least 10 cm deep into the soil and spread the gypsum.


Add a little bit of water.


Mix everything well and leave it.

Check after 2-3 weeks to see if there is any improvement. You can repeat the process if you are dealing with soil that is heavily rich in clay.

Instead of water, you can add a liquid clay breaker (more about it below) or compost for a stronger effect.

Organic matter

If you want to naturally break down the heavy clay soil in your yard and boost your plants’ growth, then organic matter is just the thing you need. In addition to gypsum, which is among the most popular remedies used on clay soil, there are multiple other soil conditioners.

Mulch, compost and biochar are among them, just to name a few. All of them can significantly improve clay soil’s structure and act as fertilisers, bringing a cocktail of organic nutrients to your greenery. The preferred soil amendment is normally spread on top of the lawn or freshly-turned ground, then left to decompose on its own.

In addition to enriching the soil, mulch can also help prevent cracking on summer days. Compost, on the other hand, positively influences clay soil’s drainage issues.

While all of the treating materials above can help fix your gardening problems, they won’t do it overnight. Whichever organic matter you decide to use, you have to be prepared that the effect may take months to show. The material will need to be reapplied time and time again to maintain the improvement, too.

Not sure which organic matter to apply and how? Get some tips and assistance from a skilful local gardener!

Soil aeration

As we mentioned before, compaction is a serious problem and clay soil is most susceptible to it. Compacted soil is very dense due to the effect of water on the particles, which are pressed even closer together, leaving no space for oxygen. When you also add foot or machinery traffic, you end up with heavily compacted and very unfavourable soil for your plants.

Therefore, a fast and easy way to allow air back into the clay soil is to aerate your lawn or garden. You can do it manually with a garden fork or rely on professional aerating machines. Here’s how you can approach this:

How to spike your lawn or garden:

Check the condition of the soil. If there is heavy rain and the ground is still soaked with water, it is best to wait for it to become at least damp. Trying to work wet and muddy clay soil can be a real nightmare, so choose your best moment.


Spike your lawn or garden at least 10 cm deep with the help of a garden fork. A professional aerator can even go as deep as 15 cm.


You can use this opportunity to add gypsum, compost or other organic materials to help improve the soil’s overall drainage and prevent root rot.

Commercial products

While treatment with the previously mentioned materials can work, the time it will need to reveal results is not very little. Therefore, if you are looking for a way to break down your clay soil faster, we recommend trying a liquid clay breaker.

Specifically made for clay, as the name suggests, these products are easy to find in specialised stores and can be applied on both the lawn and the garden. Rich in calcium and other important nutrients, they can serve as fertilisers, as well.

Liquid clay breakers effectively improve clay soil’s drainage, reducing compaction without the need to dig or aerate manually. As there is a large variety of such products on the market, it is best to check with a friend who has used a good one in the past, or consult with someone at the store about the properties of the product before purchasing one.


Usually used on lawns, the technique of spreading a thin layer of soil mixture on top of the current soil can be done for gardens too, although mainly in raised garden beds and the like.

When applied on the lawn, the new topsoil should be spread so thin that part of the grass blades is visible above it. It can be applied after an aeration procedure, which will allow the new soil to penetrate and mix with the clay soil. You can check our guide on How to topdress your lawn the right way for more information.

There are different topdress mixtures available out there, but if you want to be 100 % sure that you are applying the most suitable one for your lawn or garden, an initial test can be done to determine the soil’s pH level and other characteristics. This is best left to a garden and lawn care specialist for accurate results and the best treatment.

Raised garden beds

Raised garden beds are ideal for growing a small patch of veggies in your backyard, especially when you don’t have favourable garden soil. If despite your hard efforts, the clay soil does not seem to improve, then we suggest you consider getting a wooden box and filling it with fertile soil.

This method is quite popular because it removes all issues caused by problematic soil, but also allows for better control over the growing plants. It is easier to keep crawling insects and other pests away from your seedlings and other greenery, as the raised garden bed can be easily covered at any moment.

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Which Australian plants grow well in clay soil?

Fixing clay soil can be a long and dreadful process and we understand well that not everyone has the nerves and time to invest in such a task. If you are one of those people, then there is an easy alternative – grow plants that favour moisture and can thrive even in waterlogged clay soil.

So here are our suggestions for different flowers, trees and grasses to grow in the Australian climate:

  • Eucalyptus cinerea (also called mealy stringbark or Argyle apple)
  • Callistemon Endeavour (known also as Callistemon ‘Splendens’)
  • Hardenbergia violacea (called false sarsaparilla, happy wanderer, vine lilac)
  • Brachyscome
  • Banksia (species like ericifolia, serrata, paludosa, etc.)
  • Acacia (species like decurrens, melanoxylon, fimbriata, etc.)
  • Carex (fasicularis or appressa)
  • Ficinia nodosa
  • Buffalo Grass
  • Bermuda Grass (Cynodon dactylon)
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  • While rich in nutrients, clay soil has several disadvantages: poor drainage and subsequently high water retention, compaction, and cracking when exposed to heat.
  • There are two ways you can break down clay soil and they involve either some kind of organic material (gypsum, compost, mulch, etc.) or spiking with tools or machinery.
  • There is also the alternative to introduce your own fresh and more workable soil through topdressing or building a raised garden bed that will help your plants thrive without having to worry about the clay’s disadvantages.
  • Still, you can make the best of the situation by introducing a variety of Australian plants that can grow well in clay soil.

Still struggling with the clay soil in your backyard? We can help! Get in touch with an expert gardening specialist with only a few clicks!

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