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dethatch or aerate?

Discussion in 'Pesticide & Herbicide Application' started by mrkosar, Oct 5, 2006.

  1. mrkosar

    mrkosar LawnSite Senior Member
    from Ohio
    Posts: 664

    i have several lawns where there is 2 inches or more of thatch from probably chemlawn type applications. i am now faced with the challenge of educating these customers on why they have insect and disease damage because of their layer of thatch.

    what are your guys opinions on aerating lawns like this or dethatching?
    i aerated a few and it looks like it didn't reduce the thatch much. will i be able to dethatch in the spring as long as i do it before the premergent is put down? also, are dethatching machines as annoying and hard to move around as aerators?

    i've always been toward dethatching seems to do more harm than good, but don't see how to get rid of this excessive thatch without doing it.
  2. dcgreenspro

    dcgreenspro LawnSite Senior Member
    from PA
    Posts: 689

    you will actually remove more thatch aerifying that verticutting. I would do it two directions, and maybetopdress and seed and drag in.
  3. ant

    ant LawnSite Silver Member
    Posts: 2,442

    if you have that much thatch,aerate the s____ out of it 3 x per yr for 2 years
    and you will be fine
  4. Jason Rose

    Jason Rose LawnSite Fanatic
    Posts: 5,858

    The term "dethatching" really is a misnomer, Powerraking is really the correct term to use when talking about a machine with either spring tines or soild metal flails, either only removes the dead grass above the surface and does very little to remove real thatch. I'm faced with some similar problems, one lawn in particular, that the thatch has becom so much that finally this year with the heat the grass died and now I can't get new seed to germ in thatch!

    Point is, the others are right, aeration does MORE for thatch than dethatching ever would. I'm also of the same mindset as you, against powerraking... I'd bet that over HALF of what is removed is green when using real power rake.
  5. thecompletehome

    thecompletehome LawnSite Member
    Posts: 24

    If you have over 2 inches of thatch, you need to use a power rake. Aeration is great for compaction issues, but it does not do much for thatch buildup. Power rakes actually cut into the thatch layer and pull up the thatch that has built up. You then go back and physically remove this thatch by raking or mowing. However, with an aerator you leave the plugs and they eventually break down back to the soil, with nothing being removed including the thatch.
  6. Mr. Vern

    Mr. Vern LawnSite Senior Member
    Posts: 632

    I am very surprised that some out there believe that aerating is more effective in removing thatch than vertical mowing. That has definitely not been my experience. We used to recommend doing both at the same time in the fall, but if you can only do one we have found that vertical mowing is the way to go. The logic that I have followed is that thatch is not dead grass, it is the stolons and rhizomes that are used to spread the plant. These fibers(as opposed to dead grass) are very fibrous and do not decompose quickly. That is why thatch will build up in certain grass types (creeping grasses). With vertical mowing you actually tear these fibers (which are growing horizontally) loose and therefore break up the thatch. On the flip-side when you aerate you simply either punch a hole, or if you use a plugging aerator you punch a hole and remove the soil/thatch. I have seen lawns so badly thatched that the aerator removed almost no dirt, but it was all thatch. I find it hard to believe that randomly punching holes into the thatch and then leaving the highly fibrous material still in the turf would be more effective than vertical mowing; but I will not argue my theories against another's experiences. BTW - we find the most thatch problem with Kentucky Bluegrass lawns and of course Bermuda (which is considered a weed here). Fescues do not produce nearly as much thatch because they are clumping grasses and do not spread by rhizomes and stolons
    Hope this helps.
  7. Mscotrid

    Mscotrid LawnSite Bronze Member
    from USA
    Posts: 1,456

    If your dealing with 2" of thatch you have quite a problem on your hands. More than likely turf is subsiding more in the thatch that in the soil. Nutrients are being binded up, moisture issues etc.

    Unlike some other opinions I would not recommend Aeration as a primary method of thatch management. Like Mr Vern, I would go with a Verticut machine. They are less invasive than a Powerrake but will remove quite abit of debris. This might be a multi step program over the next couple of years. You cannot remove that much thatch at one time without causing damage to the existing turf.
  8. upidstay

    upidstay LawnSite Bronze Member
    from CT
    Posts: 1,341

    2" of thatch? Wow. I would do both, power rake and then aerate. Then keep up the aeration every year. What aeration does is allow the microbes that would normally eat small amounts of thatch top survive. Prior to this they were probably being smothered. Now they have plenty of air to help them chow down on what you don't get with the power rake.
    Not sure if you compost, bu power raking/dethatching debris degrades down very nicely intop compost. Haul it away, let it rot, then sell it back to them as an organic soil amendment. Say it with me:
  9. HenryB

    HenryB LawnSite Bronze Member
    Posts: 1,828

    IMO,thatching is like picking a scab or scratching poison ivy. It may make you feel good but does more damage than good (in northern lawns) Thins out turf and dasmages root system leaving turf vulnerable to weeds.
  10. dcgreenspro

    dcgreenspro LawnSite Senior Member
    from PA
    Posts: 689

    numerous studies have been done on all types of turf showing that aerification does remove more thatch than "powerraking". Verticutting on the new dwarf bermuda has done wonders but for any northern grass, aerifying is your best bet.

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