Lawn Aeration and Lawn Scarification: The Ultimate Guide

Have you noticed your lawn going a bit brown or moss developing? It might be a sign that it is time to scarify and aerate your lawn.

Lawn scarification removes thatch, while lawn aeration loosens compacted soil. Due to this, these processes are often seen as separate, but they work best when combined.

By scarifying and aerating your lawn each year, you give it the best chance to stay healthy, moss-free, and protected from pests.

Lawn Scarification vs. Lawn Aeration

In simple terms, lawn scarification is a maintenance technique that removes thatch from your lawn. This is usually done with a rake or a scarifying machine.

But what exactly is thatch? The term refers to a layer of dead grass, moss, and other organic matter that forms on top of your lawn naturally over time. A thin layer is beneficial, helping your lawn retain moisture and often acting as insulation to protect both the soil and your grass roots. Yet, it can cause a lot of problems once it gets too thick.

Generally, it should be kept below ½ inch, as a thicker layer will prevent water and nutrients from reaching the soil and your turf’s roots. This can result in slower growth of new grass, along with your lawn developing moss and weeds. It can also provide a breeding ground for pests and diseases.

Lawn aeration, on the other hand, works best after scarifying your lawn - scarifying loosens the soil, making aeration more effective. It is a process of creating small holes in the ground to help air circulate and loosen compacted soil. This helps water and nutrients reach the grass roots.

There are two main ways to aerate: spike aeration and plug aeration.

Spike aeration pokes holes in the ground without removing any soil. It's faster than plug aeration but does not go in as deep into the soil, making it a good choice for lawns that aren't too compacted.

Plug aeration uses hollow tubes to remove small plugs of soil. These can then be left on the lawn to break down and act as a natural fertiliser, which also helps break down thatch. Because the holes created are bigger and stay open longer, this lets water, oxygen, and nutrients reach deeper into the ground. This method is best for heavily compacted soil.

The Benefits

Stronger, Thicker Lawn: Removing unnecessary thatch and breaking up compacted soil improves air circulation, allowing your lawn to absorb more water and nutrients. This results in stronger grass growth and deeper roots. It also reduces overall water usage, as less is needed to keep the lawn healthy.

Better Drought Tolerance: Stronger, healthier turf has better resistance to dry conditions.

Prevents Water Buildup: Both processes improve your lawn’s water drainage, preventing areas of standing water. This is important as too much water can damage your turf’s root system by not giving it enough oxygen and nutrients. This not only weakens the grass but can also encourage algae, moss, and fungal issues, including dollar spot disease.

Fewer Pests: Many pests that damage turf, including chinch bugs, live in dry grass and thatch. Removing it helps keep pests away. If you already have pests, it disrupts their habitat, making it harder for them to come back and reducing their numbers.

Reduced Moss and Weeds: Scarification helps remove moss and weeds from your garden by pulling them out. Increased airflow and sunlight from both processes also prevent moss from returning as it thrives in damp, compacted soil. Healthy grass growth also makes it harder for weeds to take hold in the future. Overseeding the lawn after aeration can further help to stop moss and weed regrowth.

When To Do It

It is a good idea to scarify and aerate your lawn once a year to keep it healthy and looking great. However, depending on your grass type and how often you use your garden, you may need to do this twice a year - once in the spring and again in early autumn. In spring, grass grows quickly and recovers well, but autumn is a better time for a heavier scarify. This is because exposing the soil in spring can increase the chance of weeds. It is also important to aerate your lawn one or two days after a rain shower, when the soil is still slightly wet.

But how can you tell if your lawn needs scarifying more than once a year? Look out for a few signs. First, check your soil regularly for bare patches and try to push a garden fork into the ground. If it’s hard to do, or if your lawn doesn't drain well, for example, after heavy rain, the soil might be compacted and needs help. You should also check for thatch. Dig up a small part of your lawn, around 3 inches deep, and see how thick the thatch is. Another sign of too much thatch is if your lawn turns brown after mowing. This could mean the thatch is stopping your grass from getting the nutrients it needs to stay healthy.

How To Do It:

Before you start, mow your lawn so that the grass is about 1 inch high. This is important because the process can leave some bare patches, but these can be fixed later with overseeding. After this, you won’t be able to mow for a few weeks, so the new grass has time to grow.

Once you've mowed, begin by scarifying your lawn. For a smaller garden, you can use a rake or manual scarifier, work in rows going up and down your lawn, pushing the rake a few millimetres into the soil. You should start seeing the thatch build-up. After this, rake diagonally across the lawn for the best results. These tools work well for smaller gardens.

For larger gardens, a mechanical or electric scarifier is a better option, you can also get a 2-in-1 scarifier with an aerator built in to make this process even faster! Start with the machine set to a higher setting to avoid shocking or damaging the turf. Then, use the scarifier like a lawn mower, gradually lowering the setting. For a standard lawn, 3 millimetres is usually enough. For heavily compacted or clay soils, you can increase it up to 6 millimetres.

After scarifying, it’s time to aerate. For smaller gardens, either a manual spike aerator or a hollow tine aerator works well. If you don't have these, a garden fork will do. Push your tool into the ground 4–5 inches deep, then pull it out, ensuring the grass lifts slightly. Leave a 6-inch gap between each hole. Some people use aerating shoes - just strap them to your regular shoes and walk evenly across the lawn.

For larger gardens, an electric or mechanical machine is a better choice. Turn on the machine and adjust the settings based on your soil type and how deep you want the spikes to go. Then, walk slowly across the lawn.

Once you’re done, your garden may look worse than before. This is normal. To help your grass recover, add topsoil to fill in any holes and overseed your lawn.

Lawn scarification and aeration are both important and work best when done together. Scarifying removes excess thatch layer, helping water, air, and nutrients reach the soil. Lawn aeration, on the other hand, loosens compacted soil, creating ideal conditions for healthy grass growth. If you only scarify, the soil may still be too compact. If you only aerate, thatch buildup can still block essential nutrients from reaching the roots.

By combining both methods once or twice a year, you will help your lawn grow stronger and resist pests, moss, and weeds.