If your lawn is losing its luster and weeds are speckling its once-perfect complexion, your grass may need a spa day. Dethatching and aeration are two of the best pampering treatments you can do for your lawn to get it back to its healthy, glowing self.
We’ll walk you through whether your lawn needs dethatching or aeration, or if it could benefit from both.
- Dethatching and aeration: The basics
- Dethatching and aeration tests
- Signs your lawn needs dethatching or aeration
- When to dethatch and aerate
- Methods of dethatching and aerating
- Benefits of dethatching and aeration
- Giving your lawn the spa treatment
Dethatching and aeration: The basics
What’s the difference between dethatching and aeration? Their names are great clues: Dethatching fixes thatch problems, while aeration loosens lawn soil and fixes compaction problems (it gives your soil more “air”).
Whether your lawn is spongy and diseased or rock-hard and patchy, dethatching and aeration are long-lasting treatments that can work together or separately to improve the flow of nutrients to roots.
Thick thatch and dethatching
Like a good dandruff treatment rakes up dead skin from your scalp, lawn dethatching rakes up excessive debris and organic matter sitting on your soil’s surface.
The problem: Thick thatch acts as a barrier against sunlight, water, oxygen, and nutrients. It diminishes soil quality and stifles root growth.
The solution: Dethatching is the process of vigorously raking up excess thatch (the layer of dead grass, leaves, and other organic matter between grass blades and the soil surface) to give soil and grass roots access to water, oxygen, sunlight, and nutrients.
- A thin layer of thatch is actually healthy for your lawn: It provides nutrients for earthworms and beneficial microbes, and it insulates soil during extreme temperature shifts. Thatch becomes a problem when it’s more than half an inch thick.
- A thick layer of thatch is a symptom of larger lawn and soil problems that will need to be fixed to prevent an ongoing thatch problem.
Compacted soil and core aeration
Aeration is like acupuncture for your lawn, but instead of thin needles, aerators have hollow tines that remove soil. Aeration loosens your lawn’s tight muscles and encourages better circulation of oxygen and nutrients.
The problem: Compacted soil restricts root growth and doesn’t give roots space to receive water, oxygen, and nutrients from the soil surface.
The solution: Core aeration (also known as plug aeration) involves poking out small cores of soil from your lawn to relieve soil compaction, give roots space to grow, and increase the flow of nutrients, water, and oxygen to roots. While dethatching removes the layer of thatch above the soil surface, aeration removes actual plugs of soil from your yard.
- With looser, more nutrient-rich soil, root systems can spread out and grow deeper into the soil.
- Holes in your yard may not be glamorous, but they’ll quickly fill in with dense, healthy grass.
- Aeration actually decreases your need to dethatch: Looser, less compacted soil stimulates beneficial microbe growth. Microbes help decompose the thatch layer.
Dethatching and aerating
Can your lawn have both thatch and compaction problems? Unfortunately, yes. If your lawn has both a spongy brown carpet and rock-hard soil, it’s a great idea to give your lawn the full spa treatment.
You’ll want to dethatch before you aerate: Dethatching removes debris to make lawn aeration a whole lot easier and less time-consuming.
Dethatching and aeration tests
Testing whether your lawn is thatchy or compacted is a piece of cake.
Does my lawn need dethatching?
To measure your thatch, simply take a sample of your lawn and measure thatch depth:
- Dig a 3-inch-deep hole in your yard and remove a small slice of soil.
- Measure the brown, spongy thatch layer between the grass blades and the soil surface.
- If the thatch layer is over half an inch long, your lawn could use dethatching.
Alternatively, you can press a stick, a ruler, or your finger into the thatch layer. Measure how deeply you can push into the spongy layer before you reach the soil: If you can push more than half an inch, it’s time to dethatch.
Does my lawn need aeration?
Shallow root depth is a strong indicator of soil compaction.
- Cut out a small section of lawn at least 6 inches deep.
- Use a ruler to measure the length of your grass roots.
- If grass roots are growing only 1 to 2 inches deep, your soil probably needs aeration.
You can also test whether your soil is compacted using the “screwdriver test.” It’s not as reliable as a full cross-section, but it’s a quick, helpful indicator of compaction. If you can easily push a screwdriver 3 inches into moist soil, then you probably don’t have a compaction problem.
Signs your lawn needs dethatching or aeration
With excess thatch and soil compaction come a host of lawn symptoms. These symptoms can clue you into what’s wrong with your lawn and help you decide which treatment it needs.
Your lawn may need dethatching if…
- The ground is spongy and springy to the touch.
- Grass blades are weak.
- Grass is thinning and dry spots are appearing.
- Weeds are invading.
- Grass is losing its healthy, green color.
- Your lawn is developing an insect problem.
- Your lawn is more sensitive to temperature extremes.
- Fungal diseases are infecting your lawn.
Your lawn may need aeration if …
- Soil feels hard to the touch.
- Grass is thinning or developing diseases like brown patch.
- Your lawn isn’t draining properly during rainstorms.
- Weeds are invading.
- Grass is turning yellow.
- Grass is growing slowly.
- Trees and shrubs are showing symptoms of stress (wilting, leaf scorch, early fall color, or dieback).
Symptoms of thick thatch and compacted soil can be quite similar. To confidently diagnose your lawn, check your lawn’s symptoms and then use the tests we discussed above.
When to dethatch and aerate
Your schedule for dethatching and aerating depends on where you live and the type of grass you have.
When to dethatch
It’s important to dethatch during your region’s growing season to minimize lawn stress.
- For cool-season grasses (grown in the northern parts of the U.S.) like Kentucky bluegrass and creeping red fescue, dethatch your lawn in early spring or late summer to early fall.
- For warm-season grasses (grown in the southern parts of the U.S.) like Zoysia and bermudagrass, dethatch your lawn in late spring to early summer.
- If you live in the Transition Zone (the middle slice of the country extending from California to Virginia) or want specific advice for dethatching in your region, it’s a good idea to contact your local extension office.
Avoid dethatching when your lawn is dormant or stressed. Make sure you don’t dethatch in the peak of summer heat or during a drought, as this can severely damage your lawn.
How often to dethatch
You’ll only need to dethatch if thatch becomes an issue. As long as the thatch layer stays thin, nutrients can reach the soil and grass grows thick and healthy.
With proper lawn care maintenance and grass seed that isn’t prone to thatch, you may only need to dethatch your lawn every few years. However, some grass species like bermudagrass, bentgrass, and Kentucky bluegrass build a thick thatch layer and will likely need annual dethatching.
When to aerate
Just like dethatching, you’ll want to aerate during your region’s growing season to ensure that your grass quickly recovers.
- For cool-season grass lawns, fall is the ideal time to aerate. While cool-season lawns can be aerated in either early spring or early fall, fall aeration is preferred. Most weeds are not actively germinating in fall, so they’re less likely to sprout in the holes.
- For warm-season lawns, aerate in late spring or early summer for swift grass recovery. To avoid lawn stress, do not aerate at the peak of summer heat.
How often to aerate
Since aerating is preventative, it’s usually done annually. However, your soil type will determine the best routine for your lawn.
- If you have sandy soil with few drainage issues, you’ll only need to aerate every two or three years.
- If you have heavy clay soil or if your lawn has a lot of heavy foot traffic, it’s a good idea to aerate every year or even twice a year.
Methods of dethatching and aerating
Dethatching involves forcefully raking thatch up from your lawn. Dethatchers have curved metal blades that slice into your thatch and pull it up. You can adjust the blades to best suit your lawn’s amount of thatch buildup.
Depending on your lawn size and thatch level, you can dethatch using a:
- Manual dethatcher (also known as a thatch rake): Manual dethatchers are rakes with short, curved steel blades that cut into thatch and pull it up. Using a manual dethatcher is like raking your lawn, but with more muscle involved.
Best for: Small lawns with a mild thatch problem.
- Electric (corded) dethatcher: Dethatching machines look like small lawn mowers and have rotating wire tines that pull up thatch. You can use a dethatcher like a mower, making two or three passes across your yard (perpendicular to each other).
Best for: Medium lawns with a mild to moderate thatch problem.
- Power rake: Power rakes are large, mower-like machines with knife-like tines (flail blades) that rotate on the bottom of the machine, perpendicular to the ground. You can make two or three passes across your lawn with a power rake, but be careful not to scalp your lawn. Check to make sure you’re not tearing out the roots as you go.
Best for: Large lawns with a moderate to severe thatch problem.
- Vertical mower (also known as a verticutter): Verticutters have flat, vertical discs that slice down through the thatch and into the soil, creating grooves in your soil. Make two passes across your yard with the correct blade spacing and depth for your grass type and thatch level.
Best for: Large lawns with a serious thatch problem.
After you’re done dethatching, rake up the debris and compost it.
Give your grass some special care after dethatching: Fertilize, water, and overseed (if you’re not planning to aerate) to give your lawn an extra boost.
Core aerators have hollow tines that poke holes into the ground every few inches, uprooting plugs of soil that then decompose on your lawn.
Though other styles of aeration (such as spike aeration) exist, lawn care professionals and homeowners prefer core aeration for long-lasting, effective treatment.
To core aerate your lawn, you can choose to use a:
- Manual core aerator: A manual core aerator is a simple, inexpensive aeration option. It looks similar to a pogo stick, with a T-shaped handle, long steel body, foot bar, and two (or more) hollow tines that pierce the ground. Using a manual core aerator, you’ll poke holes 2 to 3 inches apart from each other all over your lawn.
Best for: Small yards and areas that need spot aeration.
- Gas-powered, push-behind core aerator: Most homeowners choose to rent a push-behind aerator for a few hours or a day. Push-behind aerators look similar to lawn mowers and will do most of the muscle work for you. Give your lawn at least two passes, “mowing” once north to south and a second time east to west.
Best for: Larger lawns with heavy compaction.
- Tow-behind core aerator: If you have a riding mower, tow-behind aeration is a relatively hassle-free way to deeply exfoliate your lawn. Tow-behind aerators have hollow tines that spin like soil-filled wheels as they move across your lawn. Drive your lawn tractor across your lawn in overlapping lines at the slowest engine speed, increasing the speed if conditions permit.
Best for: Large lawns with heavy compaction.
Make sure you leave cores of soil on your lawn after you’ve aerated. Cores act as natural topdressing, giving your lawn a nutrient lift.
After aeration, apply fertilizer and compost. Rake compost into the holes to give your roots a treasure trove of nutrients. To encourage dense grass growth, this is the perfect time to overseed. After aeration, you’ll want to water your lawn every two to three days for the next two to three weeks.
Benefits of dethatching and aeration
Dethatching and aeration aren’t just quick beauty fixes. They’ll give your lawn lasting health benefits.
Benefits of dethatching:
✓ Gives grass roots access to nutrients, water, and air
✓ Improves soil health and nutrient density
✓ Exposes lower grass shoots to more sunlight
✓ Improves grass health and curb appeal
✓ Increases root strength and depth and encourages root growth
✓ Reduces susceptibility to disease, fungus, and pests
✓ Increases drought and heat tolerance
✓ Improves the effectiveness of fertilizer, so you can use less of it
✓ Saves water
✓ Controls weeds
✓ Decreases stormwater runoff
✓ Reduces puddling and standing water
✓ Helps winterize your lawn and prepare it for spring growth
✓ Reduces the potential for mower scalping
✓ Improves grass health and root growth
✓ Increases curb appeal
✓ Reduces erosion
✓ Decreases susceptibility to disease and pests
✓ Cuts down on dethatching needs
✓ Increases drought tolerance
✓ Decreases the need for fertilizer
✓ Saves water
✓ Controls weeds
✓ Reduces runoff
✓ Decreases the appearance of puddles and standing water
✓ Helps winterize your lawn
✓ Increases the population of beneficial organisms like earthworms
Core aeration does remove some thatch because it involves extracting cores of soil, which include thatch and grass. However, the Michigan State University Extension advises that aeration “will not provide the quickest remedy” to a thick thatch problem. If thatch is your main lawn concern, you’ll want to choose dethatching over aeration.
It depends on whether or not you’re planning to overseed. If you won’t be overseeding, apply a pre-emergent herbicide to prevent pesky weeds like crabgrass from growing in the holes.
If you’re planning to overseed after aeration, hold off on a broad herbicide application. Synthetic herbicides can harm new seeds and stunt young grass growth. For a healthy lawn, spot spray if weeds emerge.
Mow your lawn right before you dethatch or aerate. You’ll want to cut it a bit shorter than usual: Mow it to half (rather than one-third) of its height.
Giving your lawn the spa treatment
If your lawn isn’t looking as lively and lovely as it used to, dethatching and aeration are lasting solutions to rejuvenate your grass and get it back to its lush, glowing self.
Ready to give your lawn a DIY makeover? You can buy a manual dethatcher or aerator or rent heftier machines from your local garden center or home improvement store.
If you’d rather leave the beauty treatments to an expert, call a local lawn care pro to take care of all your dethatching and aerating needs. You can take the day off and get your own spa treatment, with no raking or soil involved.