How to aerate a lawn and when you should do it

A manual spiked aerator being used on a lawn
(Image credit: Shutterstock)

If you take pride in your yard, you need to know how to aerate a lawn. While planting fresh grass seed, fertilizing for growth and regular mowing all adds up to healthy grass, nothing is quite as beneficial as aerating.

Aerating essentially involves puncturing the ground to allow better air circulation in the soil, and it’s something that many lawn-lovers forget to do.

Over time, your soil will be compacted from daily footfall, as well as from the weight of itself (particularly if it’s a heavy soil). This can result in a layer of thatch forming on the surface which impairs your grass from reaching the necessary water as well as nutrients. If you take the time to aerate your yard, the grass roots will be freed up, so they can access what they’re missing. This leads to healthier and greener results in the long run, so it’s definitely worth giving your yard a once-over. (You can also read about how much you should water your lawn to keep it green, according to experts.)

But before you go renting a machine, you should know that there’s a time to aerate your lawn and a time to leave it alone. Interested to learn more? Here’s how to aerate a lawn and when you should do it.    

Aerating a lawn isn't the same as dethatching it. If you're keen to learn more, check out how to dethatch a lawn. Also, here are 5 ways to improve your soil for a healthier lawn.

How to aerate a lawn in 7 simple steps 

What you’ll need

- Lawn aerator (spike or core)

- Flag markers or alternative

- Grass seed 

- Fertilizer

1. Choose your aerator — Firstly, you need to decide what you want to use to aerate your lawn. Two types of aerator exist: spike and core aerators. Spike aerators literally feature long spikes that puncture the ground as you pass over it. Core aerators, on the other hand, pull up ‘cores’ of soil as they work, leaving them on the surface. 

A close up of a mechanical aerator

(Image credit: Shutterstock)

You can find manual tools for each method so you can aerate by hand, however attachments also exist which you can hitch and tow from behind a riding lawn mower. Alternatively, you can rent or buy electric dethatcher and aerators from most home department stores, such as the Ryobi ONE+ HP 18V Brushless 14" Cordless Battery Dethatcher/Aerator ($429, The Home Depot). 

Between the two methods, core aeration is generally more effective because it leaves a much larger gap for the air to penetrate, but bear in mind it is more messy as ‘cores’ will be scattered across your yard by the time you’re done. 

2. Water your lawn — Make sure you water your lawn the day before you plan to aerate it. This will make the task much easier as the soil will break apart more freely. You can always schedule the work in accordance with the next downpour if you want to save water. You want about an inch of water across your lawn. 

3. Mark any necessary areas you want to avoid — Once you start aerating your lawn, you’d be surprised how determined you can get. So much so that it's all too easy to run over an unsuspecting irrigation head.

Red flags marking spots on a lawn

(Image credit: Shutterstock)

Mark any areas you need to avoid when aerating, such as irrigation systems or tree roots. You can really use whatever you want to do this, but make sure whatever you use is noticeable and won’t get knocked out of place. We recommend the ACE Supply Orange Marking Flags ($18.99, Amazon). Remember to keep your markings for use next year as well. 

4. Make sure the ground is soft — When the day arrives to aerate your yard, make sure the ground is soft enough to work. If you’re unsure, test your aerator in a discreet spot. If it’s too firm, it might require more water and a few more days. 

On the other hand, the ground can also be too wet. If the soil is bordering on muddy, don’t bother aerating it. Wait a couple of days for it to firm up. Then try again.  

5. Aerate the lawn — Now comes the main event. To aerate a lawn, you essentially want to work your way up and down in one direction to cover the whole space, and then back and forth across yourself from a perpendicular angle. This means you will work over the same soil twice. 

A core aerator being used to aerate a lawn

(Image credit: Shutterstock)

If you’re aerating an area which suffers from particularly high traffic, such as near a pathway or across from the driveway, pass over that section with the aerator a few more times to be thorough. This is necessary because that section of soil is likely more compacted than anywhere else. 

6. Wait and see — If you used a core aerator, it may look like a bit of a mess once you’re finished, but all of that soil on top is actually a good thing. If you leave it on its own to dry and break down naturally, it will better spread the nutrients across your yard.

It should only take a few days to a week for these cores to fully decompose. Don’t be tempted to rake them away in the meantime — you will only be removing the precious nutrients your soil is imparting on your lawn.  

Holding grass seeds to plant

(Image credit: Shutterstock)

7. Apply what’s needed — Now that your lawn is fully aerated, it’s time to overseed and apply fertilizer to encourage growth. 

Remember to water well and keep an eye on it. A freshly aerated lawn will dry out much more quickly compared to a compacted one, so you will likely need to water it more frequently at first.

When should you aerate the lawn? 

Most tend to aerate their lawn in the late summer or early fall, mainly due to the heavy traffic the ground has suffered over the holidays. This gives the grass time to recover before the winter months hit as well. 

However, there’s no rule against aerating in the spring time either. Just make sure you do not do it in full summer when the weather is hot and dry — this could dry out your lawn and do more harm than good. 

A strip of lawn which has been freshly aerated with cores of soil on top

(Image credit: Shutterstock)

How often should you aerate the lawn? 

This depends on the type of soil you have, as well as the amount of traffic it gets. Soil which suffers a lot of footfall should be aerated every year, while sandy soil will only need it every 2-3 years. 

For more lawn tips, tricks, and how-tos, check out our guides on how to plant grass seed, how to make your grass greener, how to stripe your lawn, how often should you fertilize your lawn and when to do it, how to lay sod, 7 common lawn care mistakes you're probably making right now, this is when you should stop mowing your lawn for the winter and read about the 7 ways to revive dead grass.    

Katie Mortram
Homes Editor

Katie looks after everything homes-related, from kitchen appliances to gardening tools. She also covers smart home products too, so is the best point of contact for any household advice! She has tested and reviewed appliances for over 6 years, so she knows what to look for when finding the best. Her favorite thing to test has to be air purifiers, as the information provided and the difference between performances is extensive.