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Soil plug with a normal thatch layer at the top.

The "hole" truth about aerating your lawn

Aerating your lawn is a great way to reduce thatch, loosen up compacted soils and make it easier for water and nutrients to reach the roots of your turf.

Even with the best care available, lawns can thin out and lose color due to excessive thatch buildup, too much foot traffic or pet traffic through specific areas that create hard or compacted soils, or periods of high temperature, high humidity, or drought. Aerifying and overseeding is recognized by turf experts such as golf course superintendents as the best treatment to control thatch, helps reduce those compacted areas, fills in bare spots and revitalize growth.

Aeration/Seeding—
the two step process guaranteed to improve your lawn

An aeration treatment removes small cores of soil and thatch to allow air, moisture and nutrients to penetrate down to the root zone. The cores brought to the surface contain microorganisms, which help the breakdown of the woody thatch tissue layer just below the lawn's crown. As the thatch layer is broken down, it is converted into organic matter that will then combine with existing soil particles.

Also, as the cores begin to breakdown over a period of several weeks, the holes gradually fill in with a mixture of organic matter and soil, and the filled hole allows roots of existing grass plants to spread out and grow deeper, creating a healthier, thicker lawn.

Ideal time for Aeration

Because the aeration process is stressful on lawns, it should only be done during periods just before active growth is expected. For cool season grasses, those typically found in the northern half of the country, this would be in early spring or early fall, the 2 times of the year when cool season grasses really grow. During the hot summer months, cool season grasses really slow down in the growing department and this is not a good time to be aerating. If you're planning on aerating in the spring and you plan on using a crabgrass control product, you'll want to aerate before the pre-emergent application is made, which is as a rule around the time when forsythias first start blooming.

For warm season grasses, the highest period of growth is when it's warmest. So aeration would be good if done in early summer.

Overseeding in cool-season areas, will fill-in bare or thin spots and help build a thicker lawn faster. The new seed quickly takes root in the freshly aerated lawn and provides new life to your already established grass. As your lawn gets thicker and healthier, your new grass plants help reduce the chance of new weeds sprouting.

Applying Lime

If you've done a soil test and your pH levels are out of whack and you need to apply lime, do this immediately after aerating. Applying lime to the soil surface at best only modifies the top 1/2" of the top soil. Applying lime after an aeration will help amend the soil to the depth of the aeration holes.

Liquid Aeration

You may have heard this term used, but what does it mean. Well, liquid aeration is really not aeration at all, but the producers of the product say their product helps improve soil structure, compaction and drainage without disturbing the soil. The liquid solution is claimed to penetrate heavy clay soil, break apart the bonded clay particles to create a space between these separated clay particles that allow for better water and oxygen penetration. Once the soil is "opened up" an environment is then created that allow microbes to develop do the rest. When you readthe fine print, you'll find that it will take multiple applications for heavy clay and may take up to 6 months or more before you'll notice any difference. Any immediate difference a user might see is most likely due to the increased quantities of ammonium and nitrates in the solution.

Should you aerate in sandy soils?

Yes, but there is different machinery to be used. Instead of using a machine that pulls out plugs of soil, use equipment that pierces the soil with a sharp spike. This type of equipment is not recommended for heavy, clay type soils as it further compacts the clay.

Soil Sample Corer

Your lawn care provider suggests you should aerate

Aeration is a common service provided by most professional lawn care providers. If it's not included in your annual program, they will definitely suggest you should have one because your soil is compacted or it has too much thatch. This may or may not be the case.

A reputable lawn care provider will provide you with a core sample from your lawn that clearly demonstrates the thatch layer. You shouldn't have to squint to see the thatch layer as it should be about 1/2" thick or so just underneath the grass and above the dirt.

If you have a visible thatch layer more than 1/2" thick, you need aeration and will probably need it for at least 2 years and perhaps twice a year. If you don't have that thick thatch layer, but you haven't had an aeration treatment for several years or more, it would be good to have done. If you just had an aeration last year, and no serious thatch buildup, skip it for this year.