Lawn aeration is a relatively new idea. It started when the people who developed what we now know as the incredibly lush, green lawns developed for golf, realized that grass actually needed to be aerated to loosen the soil and add oxygen to the soil.
Funny enough, landscapers developing water features and building ponds also realized that water also needed to be aerated, to release noxious gases and increase the levels of dissolved oxygen in the water.
But none of this is too strange, because we all need oxygen to survive, and if we aerate lawns and the water we use for our ponds, we will make the lawns and water a lot healthier. It makes sense, really.
On the other hand, if lawns are not properly aerated, they will tend to be compacted and there won’t be sufficient oxygen from the air for the grass to develop and thrive.
Problems that arise from soil compaction
Lawns become compacted very easily, quite simply because we walk on them or play on them. The lawns that children play on, or those that are close to entrance areas, driveways and patios, as well as those that are used for various sports activities, all have to take a lot more wear and tear than lawns that simply look pretty. Why do you think public properties that have beautifully manicured lawns so often have signs that say: “Keep off the lawn?” Quite simply, they don’t want people treading on the lawn because their weight will inevitably compact the soil and adversely affect the growing grass.
When the soil that grass is growing in compacts, oxygen is not able to penetrate adequately and, at the same time, toxic gases from the soil can’t escape. The effect on the grass is that it is never very healthy. It also becomes susceptible to attacks from pests and diseases and it can’t withstand the many environmental stresses that it is subjected to.
Benefits of aerating your lawn
Most lawns benefit from regular aeration because it immediately relieves compaction by loosening the soil, making it easier for the grass roots to establish and spread. The core holes aeration produces allow water, oxygen and all the other essential nutrients to get directly to the roots.
The cores of soil are generally left on the surface of the soil, and as they break down, they play the role of a kind of top dressing. This slows down the buildup of thatch, which is the layer of dead plant material that gradually builds up between the growing grass and soil in most lawns. While it is beneficial to have a layer of thatch to provide padding in the lawn, this shouldn’t be thicker than half an inch. If thatch builds up to more than an inch new grass roots may not be able to penetrate the soil and the grass will lose condition. It will also become more susceptible to disease and pest infestation.
Aerating in spring is a good way to start the growing season. Aeration in summer is great for heat-stressed lawns. And aeration in the fall is a good way to prepare lawns for the winter months ahead.
How to aerate a lawn
When aeration of soil is done correctly, hollow tines (or prongs) of a special fork or aerating machine are pushed into the soil to a depth of about two or three inches. Then when the tines are taken out of the soil they remove cores of soil the size of the hollow tines. If you use an ordinary garden fork you can spike the soil, but because an ordinary fork cannot remove cores of soil, it does not aerate the soil.
There are various types of aerating machines; the sort you would use for your garden lawn will produce between 8 and 16 holes per square foot.
Here are a few tips for successful aeration:
- Mow the lawn before you aerate it.
- Don’t mow the lawn for at least a week after aerating it.
- Make sure you know where all your sprinklers and pop-ups are otherwise you might damage them.
- It’s a good idea to water the lawn before aerating it because aeration is most effective when the soil is slightly moist.
- Aerate high traffic areas (where people frequently walk or children play) more thoroughly than other areas.
- Leave the cores on the surface of the grass so that they can break down naturally.
- If your soil is poor or full of clay then remove the cores and top dress the lawn instead.
- Fertilize the lawn after aerating it.
Aerating and reseeding
Even the best kept lawns deteriorate over time. But reseeding (or over-seeding) the lawn can work wonders and prevent the need of a complete renovation of the lawn.
The ideal time for reseeding is the same as for seeding a new lawn – early fall. If there are lots of weeds in the lawn pull them out first, or spray with a non-selective herbicide containing glyphosate. This will eliminate the possibility of weeds absorbing the nutrients you need for the seeds to germinate and grow into healthy, new grass plants.
Aeration is a vital step in reseeding, but first mow the lawn as short as possible. Then aerate the soil to relieve compaction. Remember that those little plugs of soil you pull out will create hundreds of little openings for the seeds, water and air.
The next step is to cover the aerated lawn with topsoil – ideally screened topsoil that has been mixed with compost. Spread to create a layer about ½ inch thick. Then sew your seeds, either by hand, using broad sweeping movements, or use a spreader. If you use a spreader, a good tip is to apply half the seed first, then go back over all the areas to be reseeded, but in a different direction.
Settle the seeds by pulling the back of a rake over the reseeded area. And then roll the lawn.
Last of all, give the lawn a thorough watering. Keep it moist for about two weeks to ensure germination takes place.
Don’t be tempted to mow the law until it is at least three inches tall.