The Scotts Way
How to Aerate & Dethatch Your Lawn
Too much thatch can weaken your lawn. You have two ways to remove it: dethatching and aerating.
If your lawn doesn’t seem to be growing as well as it should, even though it’s being fed regularly, it may be because of either thick thatch or compacted soil (or both). In both cases, the grass is suffering because air, water, and nutrients aren’t able to move freely into and through the soil, and are having trouble reaching the roots. You can tell your soil is overly compacted if you can’t easily insert a screwdriver into it. When thatch (bits of grass that have died and gathered just above the soil line) is too thick, your lawn will feel spongy, and it will be difficult to stick your finger through to the soil.
Either way, you need to take action. If your lawn’s failure to thrive is due to compaction, you will want to aerate it. If thick thatch is the problem, you will instead need to dethatch your lawn. Here’s how to do both of these simple fixes.
Lawn aeration, coring, and aerifying are different terms you might hear for the same procedure. A core aerator removes plugs of soil from your lawn, which helps loosen compacted soil and allows vital air, water, and nutrients to reach the roots. You can either aerate your lawn yourself or call a lawn service. If you plan to DIY, rent an aerator (you’ll need help and a truck to transport it) and follow these tips.
- The day before aerating your lawn, apply 1 inch of water to the lawn to soften the soil.
- Make sure to mark any sprinkler heads or shallow irrigation, septic, or utility lines so that you won’t accidentally run them over.
- For lightly compacted soil, go over your entire lawn once with the aerator, making sure to follow directions for use.
- If your soil is seriously compacted (or if you’ve never aerated it before), go over the entire lawn twice, with the second pass perpendicular to the first.
- The aerator will remove plugs of soil. Leave them on the lawn so they can break down and add nutrients back into the soil.
- Once you’ve finished aerating the lawn, water it well.
- Apply Scotts® Foundation Soil Improver to help strengthen, further alleviate compaction, and improve the structure of your soil. Then follow up with an application of Scotts® Turf Builder® Lawn Food to provide the nutrients needed to help the lawn recover. (Need a spreader to apply the fertilizer? Check out our article on How to Choose Lawn Products and Spreaders.)
- Water your newly aerated lawn every 2-3 days during the next couple of weeks.
You want to aerate the lawn when your grass is in its peak growing period so it can recover quickly—think early spring or fall for cool-season grasses, and late spring through early summer for warm-season grasses. If you have high-traffic areas or heavy clay soil, you will want to aerate every year. If you have sandy soil or your lawn is growing well, aerating the lawn can happen every 2-3 years.
Thatch is a layer of living and dead grass shoots, stems, and roots that forms between the green grass blades and the soil surface. Sounds kind of gnarly, we know. However, a half-inch of thatch is good for your yard; it provides insulation from temperature extremes, helps keep moisture in the soil, and gives it a protective layer of cushioning. It’s when thatch builds up to more than ¾-inch thick that’s the problem. Too much decaying plant material can lead to increased pest and disease problems (and reduce the effectiveness of control products), stop oxygen and moisture from reaching the soil and grass roots, and keep your lawn from draining properly. So when the thatch stacks up, some of it’s got to go.
You can hire a lawn service to dethatch your lawn for you or follow these steps to do it yourself.
- Tackle small lawns with a dethatching rake, and rent a dethatcher (also known as a vertical cutter, verticutter, or power rake) for larger lawns
- Mow your lawn to half its normal height before you begin dethatching. (FYI: Don’t fertilize before dethatching.)
- Use a dethatching rake like you would a regular rake. Dig the tines into the thatch and pull it upward, helping to loosen and remove the buildup. While you rake, you should feel and see the thatch separating from the soil.
- If you’re planning to rent a dethatcher, mark any shallow irrigation lines, sprinkler heads, or buried utility lines before starting. This is no time for surprises!
- Ask the rental agency to adjust the spacing and cutting depth for your grass type. The blades should be set to cut no deeper than ½ inch into the soil. Make sure to get directions for how to use the dethatcher, and follow all of them carefully. (Yes, ALL of them!) A dethatcher is heavy, so ask for help loading and unloading it, and know that you’ll need a truck to move it.
- After dethatching, your lawn will look ragged. Use a leaf rake to get rid of the thatch you loosened up.
- If bare spots were created by dethatching, use a patching product, like Scotts® EZ Seed®, to repair them.
- Now you can feed the rest of your grass. Once that’s wrapped, water your entire lawn to help it recover from all of the poking and prodding.
The best time to dethatch your lawn is when it’s actively growing and the soil is moderately moist. For cool-season grasses, that’s early spring or early fall. For warm-season grasses, dethatch in late spring through early summer (after the second mowing). That's when your grass is growing most vigorously.