What is Lawn Aeration? Why, When, and How to Do It?

Maintaining a beautiful lawn is not an easy task. That is of course if you’re not employing essential lawn care practices such as well-timed mowing, watering and fertilizing. But those aside, it’s also extremely important to ensure that the soil beneath your grass gets lots of nutrients. And what better way to do that than by aerating your lawn!

Lawn aeration is crucial for a healthy lawn, as it allows air, water, and other nutrients to easily penetrate built-up grass and lawn thatch.

So if you’re new to lawn aeration, this article is just the thing for you. Here you will find everything you need to know about lawn aeration along with some handy tips.

Get rid of thatch and make way for a beautiful lawn with this quick guide to aeration. You’ll learn why, how, and when to aerate your lawn for the best results.

What is lawn aeration?

According to Cambridge’s Dictionary, aeration refers to "a process that allows air to act on something”. When it comes to gardening, aeration is the process of poking small, long holes into the ground in order to provide the soil with good air circulation and improve the grassroots’ water and nutrient consumption.

Air circulation is very important as it lets stale carbon dioxide out, in turn, making room for fresh new oxygen to go in.

Lawn aeration also helps break through piled-up thatch in high maintenance lawns and reduces lawn compaction, which is the main cause of moss.

Why do you need to aerate your lawn?

Although there are still many things to be learned about lawn aeration, there’s one thing most experts agree on and that is that opening up the turf’s surface is beneficial for it. Air and water are essential for the soil ecosystem and the soil microorganisms in it which help naturally break down thatch thus improving the lawn.

Good drainage conditions and adequate topsoil air intake are very important for the proper growth of grassroots as they help them breathe and grow. By aerating the soil, you’re permitting air to enter into the soil, which leads to gaseous exchange. Meaning that the grassroots suck in oxygen and expel carbon dioxide.

Having too much carbon dioxide in the soil is not good as it can limit or completely prohibit its water and nutrients intake.

lawn aeration process and effect visualised

By regularly aerating your turf you will also allow water to enter it more easily. This plays great importance in the hotter seasons as when the weather is dry, the grassroots will require a bigger intake of water as a lot of it will evaporate or transpire through their leaves. If your grass is letting out more water than it’s intaking it will begin to turn brown and may even eventually die.

However, by thoroughly aerating an area where browning has occurred, you can restore to roots’ ability to intake moisture again. And if done right your grass’ colour will return to its regular green in just around a week.

On the other hand, if the lawn is not aerated during the cold rainy seasons such as autumn and winter completely different problems can occur. For example, your soil might experience surface sealing because of the compacting effect of walking around and using garden maintenance machines that are on the heavier side.

This can prevent water from entering the soil, in turn remaining on the surface and also restrict gaseous exchange. In the long run, this can lead to moss and fibrous growth build up. If nothing is done to relieve the soil compaction, no water or air will be able to reach the grassroots, creating the ideal conditions for diseases to thrive.

When is the best time to aerate a lawn?

There are two ideal times for lawn aeration in the UK, one is in spring and the other is in autumn. These are the seasons when the soil is usually naturally moist and is suitable for holes to be poked into it easily.

Most people prefer to aerate their lawn in spring as it coincides with the growing season of the grass. This way the grass has the opportunity to heal properly. However, since the weather in the UK can vary greatly and aeration depends a lot on weather conditions, it’s important to tread lightly. As if, for example, the soil is too wet, the holes you make will not let any air or water reach the roots as the holes’ sides will seal up quickly.

So let’s move to a schedule which best represents when and how much you should aerate. Also bear in mind that lawn aeration frequency all depends on the lawn you have.

Seasonal lawn aeration schedules to choose from

Spike your turf between 2 inches (5 cm) to 6 inches (15 cm) using a rolling lawn aerator, lawn aerating sandals, or a garden fork. You can repeat this process once every couple of months. You should, however, avoid spiking wet soil that smears and when you notice that frost is imminent as your tools can get stuck.

When and how often to spike a lawn depending on its type

  • Newer lawns need to be aerated a bit more often as their root system is not as mature and this will help them develop and grow.
  • Lawns with hard or clay soil have to be aerated at least once a year as they have a harder time getting fresh air and water to reach their roots.
  • For any other types of soil, it’s recommended that you aerate your lawn at least once on every 3 years. Of course, if you notice that the grass is looking unhealthy you might want to increase the frequency.

When aerating in Autumn try to use a hollow tine aerator as it will improve the drainage of the soil and increase its temperature. This method of aeration, however, should only be done when you’re sure the soil will have time to recover. Start aerating at the end of August through mid-October as those the months when the weather will start getting wetter rather than drier. When hollow tining beware of upcoming frost, as if the soil freezes after you’ve aerated it, it can cause the lawn to heave up.

If you decide to aerate your lawn in spring it’s best to add a slitter to your aeration equipment. As for late autumn (October-November) you can use chisel tining in order to get the ‘pruning’ effect such tines have. This will stimulate root development during the colder months.

How to aerate your lawn

Aerating a lawn is not particularly hard, but in order to do it right you will need to follow the following steps:

  • Before starting the aeration process make sure your soil is moist enough. So try to aerate the lawn a day after it has rained or a day after watering it.
  • Since most aeration equipment covers only a small part of the soil’s surface per pass, it’s crucial to do multiple passes over the more compacted areas. Not all areas need aerating, so disregard the unaffected ones.
  • If you’re using a hollow tine aerator, leave all the excavated soil plugs it creates on top of the lawn to break up and decompose and later fill up the holes left behind by the aeration process. Mowing the lawn will help break the soil plugs up and slowly return them to the holes they came from.
  • Once you’re finished aerating, it’s good practice to apply fertiliser and top dressing, as this will give your grass all the additional ingredients it needs in order to thrive. Fertilising will also change the grass’s appearance to a thick green one. Aside from applying fertiliser you should continue to mow and water your lawn frequently after the aeration to help grow healthy grass in a short amount of time.

Can a garden fork be used to aerate a lawn as well?

Under no circumstances must you aerate your lawn using a garden fork. Although spiking the lawn with a fork will improve air and rain penetration, it will unfortunately not reduce compaction.

How do you know if your lawn needs aeration?

If you’re wondering whether your lawn needs aeration, there are certain signs you can look for that will help answer that question. Neglected lawns usually become compacted and it’s easy to tell they need aeration, just look out for the following things:

  • Thatch layer - A thatch layer atop your lawn is a clear sign of poor air consumption and compaction in a lawn. Soil compaction prevents the needed amount of air and water from reaching the soil. This is detrimental for your lawn’s health as it will also impact the microbes and beneficial fungi population in it. And it’s these microbes and fungi that keep the balance of life in your soil. Without a healthy microbe population, decay will cease to occur meaning that once older plants die, they will just keep building-up until they create a soggy thatch layer. Once this layer reaches a thickness of 1-2 inches(2.54-5.08 cm) it will become a barrier and water and air penetration will be stunted even more, further worsening your lawn’s condition.
  • Lawn Disease - If a lawn has become compacted it will become more susceptible to disease. The most common lawn diseases are fusarium which occurs usually in autumn and winter, red thread in summer and rust in autumn.
  • Grass Colour - Compacted patches of lawn usually have a dry appearance. A good way to test if there’s something wrong is by adding fertilizer to this area. If the area is indeed compacted the grass will take on a ‘bluey’ tinge as the soil won’t be able to assimilate the fertilizer properly.
  • Rapid Drying - A lawn with poor moisture-holding qualities will dry faster than other healthier lawns. So if you’re in doubt compare your neighbours’ lawns to yours and see if there are any noticeable differences.
  • Rain Run-off - Really compacted soils cause the rain to run-off down the lawn.

What tools will you need to aerate a lawn?

Lawn aeration equipment falls into three categories:

This option is perfect for people with smaller gardens. Aerator shoes have underneath them 1-1.5 inch (2.54-3.81 cm) spikes and once put on are used to walk around the garden in an organized fashion. They work great in combination with lawn mowing, so consider putting them on when mowing the lawn to ensure that you cover the entire area.

If you’re wondering how to aerate your lawn by hand, well this is the equipment you’ll need. Hand aerators are designed to make specifically measured holes in terms of depth. They’re cost-efficient and are also ideal for smaller gardens. A good example of such a tool is the hollow tine aerator. A hollow tine aerator is used for removing plugs of soil to prevent the created hole from closing up quickly.

There are two types of machine aerators - small and large ones. The small ones are appropriate for small to medium-sized gardens and are used the same way you’d use a lawn mower by being pushed. Large machine aerators are usually pulled by a tractor as they are meant for larger gardens and even fields. Of course, using a machine to aerate your lawn is the most effective way, however, it’s also the priciest.