Aerating Your Lawn: Why, When, & How To Start

What Is Lawn Aeration?

Lawn aeration is a mechanical process for reducing the soil compaction in your lawn. 

It works by digging lots of tiny holes in the lawn—usually only half an inch wide—but anywhere from 1-6 inches deep. 

Aeration allows air and moisture to get down into the soil, improving the quality of the soil by increasing “pore space” – the room in the soil for water, air, and grass’ roots.

When aerating your lawn, look for a machine that will remove soil plugs from your grass rather than pushing them deeper, as the latter can contribute to lawn compaction.

Core Aeration 

The best way to aerate a lawn is by removing “soil plugs” or “cores” from the lawn, and then leaving them on the grass to slowly become reabsorbed.

To do this, you’ll need to use a gardening tool called … you guessed it, a lawn aerator.

There are some different machines you can use to aerate your lawn, including what is called a scarifier. Scarifiers work by plunging metal spikes down into the soil in a process called scarification.

However, this isn’t the most effective method of aerating your lawn, as it often doesn’t pull out the soil plugs from the ground. 

Instead, it pokes holes into the soil and leads to even more compression of the earth – which isn’t great for things like fertilizer and air.

Using a regular aerator that will pull the plugs from the earth is definitely recommended, so that your lawn can be aerated properly. 

Aeration is especially important for lawns that get a lot of heavy use – which is why you might notice a grid of holes suddenly appearing in your local sports field, once a year or so. 

It’s not alien crop circles, but simply a dedicated groundskeeper working to prevent soil compaction and keeping the grass healthy.

How Aerating Helps Your Lawn

There are many benefits to aerating your lawn to improve lawn health, including:

Thatch Reduction

Thatch is a build-up of living and dead plant matter around the base of grass, and prevents air, water, and fertilizer from reaching to the roots of your grass.

Aeration promotes the health of soil microorganisms, which helps decompose thatch and anything else that might be left on the grass. 

This leaves your grass free to absorb any nutrients it may need.

Increase Water, Nutrients, And Oxygen Movement Into The Soil 

By aerating your lawn, you’ll see your grass grow healthier with less weed activity. 

This is because your soil now has access to more eater, nutrients, and oxygen movement—which are all things it needs to be healthy.

Improve Rooting

The extra space created by aeration leads to more room for root growth, increasing the nutrients, water and oxygen that the grass can actually absorb.

This will help extend the life of your grass, and lead to a decrease in the need for fertilizer, saving you time and money in the long run. 

Decreased Fluid Run-Off

Fertilizer, pesticide, and even irrigation will have an easier time being absorbed into the soil after aeration, and it will also help prevent run-off. 

This means we can prevent nasty chemicals from leaking into our drains, lakes, and streams.

How To Know When Your Lawns Needs Aerating

If you are having trouble with poor top growth, lawn deterioration, or too much thatch, then you might need to aerate your lawn. 

It can also be assumed that heavy traffic, whether by vehicles or pedestrians, will compress the soil under your grass. It’s also recommended that you aerate your lawn if it's showing signs of rapid growth. 

You can easily check whether your lawn needs aeration, as a compressed lawn will result in poor root depth. Simply take a turf sample.

To do this, you will need to cut a section of lawn out. This should be at least six inches deep, and roughly one square foot wide. Measure the roots. 

If they only penetrate 1-2 inches into the soil, then your lawn is probably suffering from soil compression. Be aware though, that root depth is also affected by the season.

Generally speaking, you should aerate your lawn once a year. The best time to aerate is when your grass is most actively growing.

Warm vs. Cool Season Grasses

You will want to aerate your lawn when the grass is in its peak growth season. 

That way, your lawn will be able to recover most quickly from having a bunch of tiny holes poked into it. For warm season grass, aerate in spring. For cool season grass, aerate in the fall. 

You should be able to tell what kind of grass you have by noticing whether it needs to be mowed more often in summer or in winter. If you haven’t noticed a difference, you can usually tell by region. 

If you are in the Northern half of the US, you probably have cool season grass, whereas the South tends to have warm season grass.

If that still doesn’t help, just try asking at your local gardening supplies shop. They will know what kind of grass grows in your region.

Tips For Aerating Your Lawn

There are a few things you might want to know before you aerate your lawn: 

• Check for underground infrastructure, and mark it off. This includes plumbing, underground electrics, sewage, irrigation systems. 

• If you have a heavily compacted lawn, try raking half an inch of stable, mature compost over the lawn immediately after aeration.

• Overseeding is similarly done best immediately after aeration.

• Aeration works best when the soil is damp, but not wet. Wait 1-2 days after rainfall, or water regularly for a week before aeration if there has been no rain. 

• Make sure to aerate in at least two directions for full coverage.

• Make sure the lawn is mowed very short (to around 1-2 inches) before aeration.

• Check for pests, like grass grub, which can interfere with the aeration process.

Different Tools For The Job

Getting the right tool can save both time and money. 

As aerating your lawn is a job you’ll most likely be doing annually at most, it might be easier to rent an aerator than it is to buy one. When going to rent an aerator, make sure to look for one with deep, heavy spines. 

The machines can be very heavy and in high demand during peak growth seasons, so book ahead.

You could also try communicating with neighbors around renting or purchasing a machine. As the aerators are expensive and heavy, it might be worth working together to share the load—and the cost—of a good aerator.

If you are worried about pushing a heavy machine across a big lawn, there are aerators available as attachments for ride-on mowers. Also, try asking lawn care companies for the service.

Some gardening companies will aerate for a small fee, or even for free as an additional service after mowing. 

If you have very sandy soil, then it might be more beneficial for your lawn to rent a scarifier. 

Scarifiers are similar to aerators, but are often cheaper and a little more aggressive. They’re used to pull up the top layer of thatch in your lawn, but also the soil.

Try asking at the gardening supplies store for advice, as they will likely have experience working with the soil type prevalent in your area. 

If renting, make sure you are clear with how to use the machine before taking it home. An accident with an aerator can be very dangerous. Make sure pets or children are safely removed from the area before aeration.

What To Do After Aeration 

Many lawn-owners choose to nourish their lawn after aeration, as this is an excellent time to allow the penetration of compost, water, or seeding into the soil.

Here are a few helpful tips on what you should do after aerating your lawn:

• Allow any soil plugs to break down naturally. This is the most important part. 

The soil plugs left over from aeration will naturally mix with air, moisture, and nutrients, and become excellent soil as they reintegrate into the lawn. 

Regular use, mowing, and rain will help them break down and return to the soil.

• Overseed your lawn. If your lawn is looking a little sparse, this is the ideal time to overseed. 

The tiny holes left by aeration provide good protection for young grass. Just make sure that the newly seeded grass gets plenty of water.

• Water to feed grass roots. The holes allow good access to water, and if you encourage deeper root growth by watering an aerated lawn, then the grass will grow deeper roots and become healthier.

• Apply fertilizer. This is a great time to increase the nutrient density in the soil. 

Aerated soil more readily absorbs nutrients, so consider raking in compost or fertilizer if you want a more vividly green lawn.

You should try and fertilize your freshly-aerated lawn within 48 hours, before the soil settles again. 

• Apply pre-emergent weed killer if you are not overseeding. The holes created by aeration not only create a good nursery for young grass, but also for weeds. 

If you aren’t overseeding, apply a pre-emergent weed killer to stop the problem before it starts.

FAQ

Is Aerating Your Lawn Worth It?

Yes. Aerating a lawn will keep it healthy and reduce thatching. It works by making small holes in the soil to allow air, moisture, and nutrients to get in. 

It can reinvigorate a damaged lawn, and has myriad other benefits. It's a great way to get overseeding to stick, or to get proper fertilizer penetration into the soil. 

After aerating a lawn, the grass will have much deeper roots due to reduced soil compaction and an increased number of soil pores. 

Will Aerating Help A Bumpy Lawn?

Yes. Aerating your lawn will loosen soil and allow the bumps and lumps to settle. 

Should I Add Topsoil After Aerating?

Yes. Especially if you overseeded the lawn after aerating. Sprinkle over a good quality mature stable compost, or top soil in a pinch. 

You should only need a quarter inch or so. 

Is It Better To Power Rake Or Aerate?

This will depend on the problem you’re having with your lawn. If you want to remove a large build up of thatch, then you should power rake. 

Aerating, on the other hand, will increase soil health and grass root length, which reduces thatch over time. 

Can You Walk On The Lawn After Aeration?

If you reseeded after aeration, try not to walk on your lawn too much to allow the new seeds to grow. 

Otherwise, walking on recently aerated soil will actually help break down the soil plugs so they can be reintegrated into the lawn. 

How Much Does It Cost To Have A Yard Aerated?

Purchasing your own aerator can cost anywhere from $150 to thousands of dollars.

This is not including whether you want to buy compost and new grass seeds for refreshing the lawn after aeration.

If you’re wanting to get your lawn professionally aerated, the price will depend on how large your lawn is. Prices tend to range from $75 to $225.