How and when to aerate your lawn

Master the art of lawn aeration

What does aeration do for a lawn? Quite simply, it’s one of the best ways to keep it healthy and strong, and can help turn compacted, mossy lawns into lush green spaces. Our guide to lawn aeration tells you everything you need to know about how and when to aerate your lawn.

Author

David Domoney

Chartered Horticulturalist, Author and Broadcaster

What is lawn aeration?

Aerating your lawn simply means making a series of holes in the soil below the grass. This breaks up areas of compacted soil and allows air and water to reach the roots. Lawn aeration can be done manually or with mechanical equipment.

Why you need to aerate your lawn

Aerating your lawn is one of the best things you can do to keep it healthy. It improves drainage by reducing soil compaction, allowing air and water to reach the roots of the grass. This enables the roots to breathe and take up the nutrients they need to produce a thick, strong, healthy lawn. Aerating your lawn also helps to break up the layer of dead grass stems and other plant material that builds up on the soil surface. This layer is called ‘thatch’ and can form a barrier that stops water from getting to the soil. Aerating the lawn makes holes in this layer, allowing water through.

Lawn aeration tools

Depending on the size of your lawn and the type of soil you’re working with, there’s a variety of different tools that can be used to aerate it. Here are the most common lawn aeration tools:

Garden fork

A garden fork is one of the simplest tools for aerating your lawn, and the bonus is that most gardeners already have one in their garden sheds! However, aerating a lawn with a garden fork can be hard work, so it’s best used on small lawns. If your soil is heavy clay, use a hollow tine aerator instead of a garden fork.

Hollow tine aerator

Garden forks and spike aerators aren’t very effective at aerating heavy clay soils or very compacted lawns, as the holes made by the solid spikes can quickly close up again. A hollow tine aerator is a better solution for these conditions. As the name suggests, the tool has hollow tines, unlike the solid tines of a garden fork. When you press them into the ground the tines fill up with soil, and when you remove the aerator, these plugs of soil are removed as well, leaving small holes which are less likely to close up.

How to aerate a lawn with a garden fork or hollow tine aerator

To aerate a lawn with a garden fork, simply press the tines of the fork into the soil to a depth of at least 5in/12.5cm. While the fork is in the soil, press down gently on the handle so that the soil around the tines lifts very slightly. This helps to break up compacted soil. Remove the fork, move it to the next position and repeat the process until you have covered the whole area.

To aerate a lawn with a hollow tine aerator, press the tines of the aerator into the soil as far as they will go, then pull the aerator up, move to the next position and repeat. As you press the aerator into the ground, the soil cores from the previous position will pop out of the tops of the tines onto the grass. Once you’ve finished aerating, sweep these cores up and put them on a compost heap or on your borders.

Spike aerator

A spike aerator typically consists of a rotating drum or roller fitted with spikes. The aerator has a handle which allows you to push it over the lawn rather like a lawnmower. As you push, the drum rotates and the spikes penetrate the lawn, aerating it. Aerating a lawn with a rolling spike aerator is quicker and easier than using a garden fork, but still requires quite a lot of effort, so is best used on small lawns. Again, for heavy clay soils use a hollow tine aerator instead.

Powered aerators

Aerating a lawn by hand can be hard work, so for large lawns you may need to use a mechanical aerator instead. These machines are available to hire and are often able to scarify the lawn as well, thus taking care of two lawn maintenance jobs! Some mechanical aerators work by cutting slits into the ground rather than spiking holes or removing plugs of soil. The slits will allow water and air to get into the soil, promoting

How to aerate your lawn

Before aerating your lawn, mow the lawn on a low setting so that the grass is around 1in/2-3cm high. Using a spring tine rake, scarify the lawn by raking firmly over the grass in different directions to remove the thatch layer, then collect the thatch and place it in a compost heap or green waste bin. Getting rid of this layer of dead plant material improves the health of your lawn and makes aeration much easier.

To aerate the lawn manually, work your way over the lawn, spiking holes into it at regular intervals with a garden fork, spike aerator or hollow tine aerator. As a guide, allow a gap of between 6-12in (15-30cm) when moving your fork or aerator.

Work across or down your garden in straight lines in the same way as you would if you were mowing the lawn. This will ensure that you don’t accidentally miss any spots. If you are using a mechanical aerator, aerate a strip around the outer edge of the lawn either before or after aerating the rest of the lawn, so that you cover the area used to turn the machine at the end of each row.

If you are aerating by hand and your lawn is too big to tackle in one go, choose the worst area and focus on that first. Very compacted areas of lawn are easy to spot, as they are likely to have patchy, thin grass and are more prone to moss. You don’t need to aerate the whole lawn in one session – divide it up into sections and work on one area at a time so that you eventually cover the whole lawn.

What to do after aerating your lawn

After aerating heavy soils, it’s a good idea to spread top dressing over the lawn and brush it into the holes created by the aeration. Top dressing is a mixture of organic material, sand and fertiliser which helps improve soil structure, drainage and overall lawn health, as well as smoothing out any small dips in the lawn. Place small piles of top dressing over the aerated lawn and use a lawn brush or the back of a rake head to work it into the holes.

Finally, give thin, patchy lawns a boost after aerating by spreading lawn seed on the top-dressed areas, or mix some lawn seed in with the top dressing before spreading it.

FAQs

What is the difference between core aeration and spike aeration?

Core aeration creates small holes in the lawn to reduce compaction, using tools with hollow tines which remove small plugs of lawn soil. Spike aeration involves poking holes into the lawn soil using tools with solid spikes such as a garden fork. Core aeration works better than spike aeration on heavy or very compacted soils.

Is aeration necessary for new lawns?

New lawns should not be aerated immediately after sowing or laying. You should wait at least six months before aerating a newly laid turf lawn, to give the roots time to establish. For newly sown lawns, wait until the grass is growing strongly before aerating.