The process of aerating a lawn is done only occasionally but can be vital for the long term health of a lawn. A special tool called a lawn aerator is used to remove a small plug of soil from the ground, allowing water, nutrients and oxygen to penetrate deeply. Aeration is needed when a lawn develops a layer of thick thatch and/or compacted soil which prevents these vital components from reaching the roots.
Signs You Need to Aerate:
- Your grass is thinning.
- You have a thick layer of thatch.
- The grass is turning colors.
- The soil is compacted (Foot traffic)
- The weather is extreme (Humidity, heat, drought)
When to Aerate:
As a general rule, aerate your lawn once a year in the fall to early summer. Lawn aeration should be avoided in mid-summer because the lawn is likely to be in a stressed state. If weeds are abundant, avoid aerating until the weeds have been removed, as the seeds can enter the aeration holes and grow out of control.
To determine whether your lawn needs immediate aerating, take a core sample and examine the thatch layer of the core.
Thatch is the layer of dead grass which sits at the top of the soil. If the layer exceeds 1/2 inch in thickness, twice-a-year aeration is likely to be needed to get it back under control.
Being that aerating is stressful for lawns, it should be done right before the grass begins a rapid growth cycle.
In cool areas, particularly in the north, the best time is in the early spring or fall. It is during these times when cool-region grasses start to grow.
Mid to late summer is the time when these grasses slow down in growth and are weaker. Weed control granules should be set down after aerating and before the first signs of grass sprouts in the spring.
How Aeration Helps:
The holes created in the ground loosen any compaction and removes excess thatch much like a lawn scarifier, allowing grass roots to readily penetrate and spread. They also allow fertilizer and oxygen to reach the roots. Properly aerating a lawn before summer hits allows the soil to retain more water in the heat, resulting in reduced watering frequency.
The cores of soil removed from the ground contain helpful microorganisms which seep back into the ground and help break down the thatch layer. In turn, the broken down thatch is transformed into organic material which re-integrates with the existing soil.
The cores left on the lawn will break down in a couple weeks, and the holes fill in with organic materials / soil. The roots can then propagate into the filled holes which are now filled with light and fluffy material that is nutrient-rich.
Lawn aerator tools come in both manual and powered models. Manual aerators use human weight to press 2-4 hollow tubes into the ground. A plug of soil is removed from the ground and deposited onto the lawn. Some types of aerators for lawns have spikes which create holes but do not remove plugs.
Spiked tools are not as effective and should be avoided if possible. Manual tools have the ability to get into small corners and areas that are difficult for a powered too to access. They are suitable for most small-medium consumer lawns.
Some interesting additions to the industry include spiked shoes and the rolling lawn aerator. Spiked aerators are not all bad. They are actually preferred over core aerators in lawns with sandy soil.
Powered aerators attach to a garden tractor and are pulled around the yard. They are far less labor intensive than the manual tools and get the job done faster.
How to Aerate:
To make it easier for the tool to penetrate, water your lawn 24 hours before aerating. The soil should be moist and soft. Go over the lawn with your tool several times, varying the direction each pass. Several presses per square foot should be more than enough.
Avoid pressing deeply around the edges of the lawn where PVC sprinkler pipes reside. When done, all of the cores sitting on the lawn must be broken up so that they will decompose faster and release their organic material. This can be done by scratching the ground with a metal rake.
The cores can also be collected and mixed in with manure as a top dressing. A lawn roller can also be used to make the area flat again, but isn’t necessary. Follow up with thorough watering.
Bare areas can be filled in with seed immediately after aerating. The seed will grow quickly and more vigorous thanks to the aeration. Over-seeding can allow grass to overwhelm any weeds and unwanted plants, leading to a healthier, greener lawn.
The process of liquid lawn aeration uses a chemical instead of a tool to break down compacted substances within the soil. The liquid penetrate the ground and supposedly breaks up clay to create air pockets and better drainage all without disturbing the lawn. The soil then becomes an ideal growing environment for helpful microbes.
Despite these claims, the results is liquid aerating are inconclusive and may not work for everyone. It can take months to see results with this method. One good point is that the liquid can contain nitrates and ammonium which is beneficial to lawn growth.
If a soil test has revealed improper levels of pH in the soil, an application of lime can fix it right up. A lime application after aerating allows the lime to penetrate deep in the soil for a quick fix. Without aerating, the lime would take considerably longer to penetrate.
Proper Lawn Maintenance and Reducing Thatch:
Mulch Regularly: Mulching is done using a special lawnmower. The blade chops up the grass into pieces which are much smaller than what a regular lawn mower can achieve. The clippings sit on the surface of the lawn where they help hold in moisture and provide nutrients as they break down over time.
Grass Length: All grasses should be kept to a length of 3-4.5 inches. Any shorter and the lawn will lose moisture rapidly. Also, short grass can attract pests like root-eating grubs and weeds. Long grass will lean over and hold in too much moisture, creating mold. The height of the blades should be roughly equivalent to the depth of the roots. If the grass has grown too tall, cut it down in two passes several days apart. A good rule is to not cut more than 1/3 of the grass height in a given day.
Mowing Speed: When mulching, walk slower than usual in order to allow the grass to chop up finely. Set the mower to its highest speed setting. A sharp blade is a must.