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Do I Need To Aerate My Lawn?

August 20, 2012

Lawn aeration questions are high on the list when I give a clinic or talk on lawn care.  Since fall is a great time to aerate cool-season grasses, this is a very timely topic for those with bluegrass, ryegrass, fescue and bentgrass.  The best time to aerate warm-season grasses is early summer, however if you have a severe thatch problem in your Bermuda, Zoysia or St. Augustinegrass you can aerate now as long as your lawn is actively growing.

There are two main reasons to aerate.  First, when a lawn gets a lot of use (like you get with athletic fields or golf courses) the soil can get packed down and compacted, restricting the flow of water and nutrients.  There are some tell-tale signs that your lawn may be compacted.  Poor drainage is one.  If water pools up on your lawn or runs off instead of soaking in, it could be because the soil is compacted.  Lawns that look worn-out are often because of compacted soil.

Second, when a lawn has more than a half inch of thatch; water, air and nutrients may not be getting down to the roots.  The tell-tale sign to look for is if your lawn does not really turn a healthy green after feeding.  You can check your thatch layer thickness by removing a plug of grass, soil and all, and measuring the thatch layer between the green growth and soil layer.  If thatch is greater than a half inch, consider aeration.

This illustration shows that root depth is restricted by both compacted soil (far left) and too much thatch (2nd from left). Feed your lawn after aerating. The result is improved root growth as shown in the far right illustration.

Aerate your lawn by making individual holes around three quarters of an inch in diameter, three inches deep, and no more than 3 inches apart.  This is best done with an aerating machine that removes plugs of soil, not the kind that just punches spike holes in the lawn.  Follow up the aeration with a good feeding of Turf Builder.

You can rent an aeration machine, however since they are quite heavy, you may find it best to hire a professional.  If you decide to hire a service, you should schedule this ASAP as they get booked up pretty fast this time of year.

Oh, here’s some good news: after aerating, you can leave the plugs on your lawn.

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  1. I see very little discussion on zeon zoysia, or how to maintain it. in April of 2012 I lay down over 5,000 sq ‘ of zeon zoysia, it is the talk of the neighbor-hood, I want to keep it that way! As I see Scotts does not offer a specific fertilizer for this grass, and for the change of seasons, Any thoughts??

    • Hi Maurice
      Zeon Zoysia makes a nice lawn for sun and lightly shaded areas in the south and mid-south areas. I like our GreenMax Lawn Food for this grass. Begin feeding when you see about 60 to 70% green in spring and continue at 6 to 8 week intervals thru summer with the last feeding around mid September. The last feeding can be Turf Builder WinterGuard.

  2. jim permalink

    ashton, i have fertilized my lawn 4 times so far this year,3/16,4/24,6/12& 8/13.I live in northern illinois and we were in a extreme drought and still are very dry.,watering is really not an option since i have just over 11,000 sq.ft,while most of the lawn is in sun,my neighbors are too and their lawns look a lush and dark green,They don’t fertilize or spray for weeds,like i do.

    Do you think the fert.burned the lawn?I always use scotts products. Iknow fall is the best time to reseed but i’m really afraid to water the new spots in fear of drying up our well. I really don’t know what to do. HELP.

    • Hi Jim
      As I was reading your info, I really felt your pain. I posted a picture to show grass coming back from dormancy in a recent posting “Will your grass bounce back from the drought”. This may help you determine if your lawn needs to be reseeded. Relative to feeding, I am a firm beliver in pushing more of your feeding into fall for cool season grasses like those grown in northern Illinois. This would mean feeding in: Early Sept, Late Oct, Early April, Late May. If you were able to feed a 5th time, I would make this application in November. Lawn Fert can burn if temps are in the 90’s and no rain or watering near the time of application, and the lawn food is slightly over applied. If you need more advice… fire me another question.

  3. jim permalink

    ashton, we have lived at this house for 4 yrs now.The first 2 yrs,i had scotts lawn service treat my lawn and the last 2 i have done it myself to try to save money. I have always mowed my grass between 2 1/2 to 3 inch mowing height and this lawn always thrives in may and june and then starts to react to the summer time heat and slows down.The times i fertilized this year,including the one in aug, the temps were in the upper 70’s with rain expected so the moisture would help incorporate the fert. into the soil. The march app this year was done when we had a string of temps right around upper 70’s and everything was growing and turning green,then came april and we had lows in the 20’s and highs in the 30’s with rain.

    My neighbors all seem to think this lawn will come back next spring because it was healthy going into the drought,but i’m not so sure, but it sure is tough to look at.

  4. Hi Jim
    If you do not see tips of green grass starting to grow from the brown dormant grass after you August feeding and some regular water, dig up a small plug and look for white roots (brown roots would indicate dead grass). You may have had an insect problem like sodwebworm or cutworm. You would have seen moths flying up from the grass back in June/July when you mowed. I hope you start to see indications that it will bounce back.

  5. Larry permalink

    Ashton since I already have my aeration scheduled I have a question about fungus for you. we had a fungus problem(looked like cotton in the grass) with the grass dying in spots….we put down the scotts fungus treatment and followed it up 2 weeks later with another treatment…….are we now good for the seaon since we have not spied any more of the problem. we have been bagging the clippings fearful of spreading the fungus to unaffected areas of the yard.

    thanks Larry from Indiana

    • Hi Larry
      Sounds like you had Dollar Spot. Your fungicide application helped and feeding also helps. You are at the point now where you probably do not need to bag your clippings.

  6. John Swanson permalink

    I have a sprinkler system in my yard. If I aerate it myself, or hire it out, do I need to be concerned about damaging the sprinkler system? How do we avoid running over a head that is at ground level hiding in the grass?

    • Hi John
      Great question. Sprinkler heads can be a problem when aerating a lawn. For this reason, it may be a good idea to hire Scotts Lawn Service to do the job. Just point out to them where the heads are and they know how to do the job with no damage to your sprinkler system. You could do the job yourself, however I have found that the machines are so big that you may be glad to have someone else do the job.

  7. Jason permalink

    My lawn is very “lumpy.” When I mow, the lawn mower bounces around due to the uneven surface. It can really be felt when barefoot. I inherited this problem when I bought my house so I’m not sure how this happened. The lawn is well established but does not look healthy. It is very thin and is mostly a very dull greenish-brown color. There is quite a bit of thatch which is evident if I were to take a rake to it, but probably less than one-quarter inch. Should I de-thatch the lawn? I have applied Scotts steps 1 and 2 per instructions on the bags. I am preparing to apply Step 3 (albeit late) because I want to develop a beautiful yard over the next couple years. Here’s my plan of attack: rent a large “steam-roller” machine from a local hardware store (~$80 for 4 hours). This will flatten out the small uneven lumps in the yard. But I don’t want the ground to be too compacted such that grass cannot establish a resiliant and drought resistant lawn. So the next step is to pay to have my lawn professionally aerated and seeded. I was informed when reviewing quotes that one company can do a double aeration and double seed for $120. I will then rent a “Little Wonder” “bed-shaper” to establish a nice division between the lawn and the flower/mulch beds around the home and sidewalks. This costs about $80 for 4 hours. The last step is to apply Scotts Step 3 or possibly Step 4 so that the lawn contains nutrients for the Ohio winter. Based on the lawn problems and its current condition, is this plan of attack the best route to a healthy, green, level, weed-free lawn? PLAN SUMMARY: 1) dethatch, 2) steamroll, 3) double aerate, 4) double seed, and 5) Apply Scotts step 3 and 4 ( for pest control and nutrients). Your thoughts.

    • Hi Jason
      I am not a big fan of rolling a lawn except after sodding (rolling lightly after sodding helps make sure there are no air pockets between the soil and sod). The alternative is to add some Scotts Lawn Soil to the low spots. After you dethatch and aerate, put down a good grass seed. Choose one of the Scotts Turf Builder Grass Seed blends like Sun and Shade, or Heat-Tolerant Blue. Put down Starter Fertilizer the day you seed. A month after seeding, feed with your Step 4. You may even consider another feeding of Turf Builder WinterGuard in early November.

  8. Jason permalink

    Hi John
    Thanks for your reply. I assume that you are not a fan of rolling because it compacts the soil and even if you aerate the lawn it still inhibits deep root penetration? OK, Instead of rolling, lets say I use Scotts lawn soil, I’d have to do this over the whole lawn. How do I keep my yard from turning into a big mud pit? I can put down soil, cover it with straw, and keep it watered but is it too late to do that this season? Should I wait until spring?

    • Hi Jason
      You are right, rolling could add to soil compaction. If you have uneven soil that can be easily pushed down with your foot, then a light rolling could help. If that is the case, I would do it after you do the dethatch, aeration and seeding. This will help make sure the seed comes in good contact with your soil. I was suggesting the Lawn Soil if you have low spots. Good Luck.

  9. lakita permalink

    Should I run my lawn mower over the plugs to break them up?

    • Hi lakita
      You have a couple of options. You can do nothing and they will work down into the grass and break up over the next month. You can hit them with the back of a rake and they will break up. You can mow after aeration to break them up completely while they are on the lawn surface where the mower can easily reach them, however you may need to sharpen your lawn mower blade after this.

  10. Lisa permalink

    Our lawn is only 2 years old since we bought the house. Do I need to aerate my lawn now, or can it wait another year or two? Our loan is in good shape and receive their schedule treatments with TruGreen.

    • Hi Lisa
      You probably do not need to aerate. Check by cutting a plug from your lawn to see how much thatch you have. If you have more than a half inch you can aerate.

  11. Tim permalink

    Hello Ashton,
    I have the mother of all challenges for you!
    I live in West Michigan about 2 miles for the Lake Michigan shoreline, which I make reference to pointing out the sand/soil mix. We bought our home 7 years ago, the lawn was ok but nothing great. We, over the years, have seen some odd things and tried several things including hiring professional companies for treatments. This year it looks so sad… I have a mix of ponding after rain, moss along the edge of yard to woods. Bare spots, and vine type of grass or something growing within lawn. We also have moles!
    I am ready to either drop stones down and paint them green like Az. or Scrape off everything and start new, but skill, knowledge, know how, tools, and money limit my choices!

    Doomed near the dunes!

    • Hi Tim
      This is a good time to plant grass seed in your area. You would want to pick a Turf Builder Grass Seed Blend that matches your conditions (for example, sounds like you may have shade). Experts in your area recommend two or three feedings in fall. The first one could be Starter Lawn Food when you seed. Follow this up with two feedings of Turf Builder WinterGuard at 6 week intervals. This would mean your last feeding would go down about the end of November. I would hold off on any weed controls until next spring if you are seeding. The low areas where you are getting ponding sounds like you need to add more soil. Moles are likely feeding on earthworms in your lawn. They could also be feeding on grubs which are common in Michigan. It is too late to put down a grub preventer like GrubEx. Not sure what size lawn you have, so if this is too big a fix for this year, pick a smaller area of your lawn to follow these steps. The most important thing is to feed your grass this fall at least a couple of times. Good Luck.

  12. Robert Brown permalink

    I have brown patch or maybe take all patch in my St. Augustine yard located in middle Georgia. Have treated with Heritage G and Banner Maxx fungicides and do see improvement. My question is would it also be advisable to core aerate this time of year to help with fungus control.

    • Hi Robert Brown
      With the shift to cooler weather and lower humidity (especially at night) I think you will see a drop off in fungus activity. If your soil does not drain well or if you are seeing a half inch of thatch or more, core aeration will help. You can cut a plug out of your grass to get a side view of the thatch thickness. We tend to core aerate cool-season grasses in fall and warm-season grasses in late spring, however you can core aerate now. Just make sure your soil is moist enough to get a good core. If your grass has slowed growth to not need mowing, you might want to wait till next year to core aerate, especially if you think you will be doing any damage with the machine (damage is not typically a problem with a core aerator like it is with a dethatcher). Another reason to wait is we typically like to feed after core aeration and based on where you are located I would not feed St. Augustine now. (If you had Fescue, this is a great time to feed).

  13. Mike permalink

    I live in upstate NY my lawn will be 1 yr in june 2016 the seed is Kentucky blue
    rye and fescue do you reccomend areration in the fall of 2016?

    • Hi Mike
      Your lawn will probably not need aeration next fall as your thatch layer will likely not be thick enough to begin to cause problems. You can check your thatch thickness by removing a plug of grass, including the roots and soil, and looking at a side view. When your thatch layer between the green growth and the soil level is starting to get near a half inch, your lawn should be core aerated.

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