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Starting over from a weeded lawn

Discussion in 'Homeowner Assistance Forum' started by cle63, Sep 3, 2006.

  1. cle63

    cle63 LawnSite Member
    Messages: 1

    Hi. Similar to the superrman77 post, my lawn is a mess. Lots of crab grass and other weeds, and so I'm thinking that I should just till everything and seed a new lawn. I'm hoping to do this this fall and am assuming that late September is the time. I live in central Ohio. It's crossed my mind that I should just Round-Up what's there now and wait for that to die, but I'm concerned that this will hinder growth of the seeds that I plant. Any suggestions? Does the chemical in Round-UP dissipate, and if so, how long should I wait to till and then seed? An added wrinkle is that every spring we start to get snowbells and a similar plant with blue flowers (bluebells?) that take over the yard for a couple weeks. Any help is appreciated.
  2. lawnmaniac883

    lawnmaniac883 LawnSite Silver Member
    Messages: 2,613

    Spray RoundUp at the recommended rate of 6oz/gallon of water and wait one week. Go back over the area and spot treat with more round up the areas that are not completely dead.

    Two or Three weeks later, till the soil to atleast 6 inches and then go over and grade the area with a rake. Let the soil sit for 1 week to allow it to settle then either have someone hydroseed / renovate the area or try and spread seed/rake in.
  3. jeffinsgf

    jeffinsgf LawnSite Senior Member
    Messages: 641

    If your grade is good, don't till just to till. You will only bring more weed seeds to the surface. Glysophate (RoundUp) only kills green, growing plants that it touches while wet. I think the package says to wait a week, but theoretically, even that is not necessary. I would kill, core aerate and then use a slice seeder, if the grade is already where you want it. If you want to regrade, then kill, till, grade, roll, rake, seed, roll and water, water, water.
  4. LarryF

    LarryF LawnSite Bronze Member
    Messages: 1,181

    What about the billions of seeds that had been dropped by the weeds you've now killed with the Roundup? Don't you also have to do something to get rid of them? If not, won't they germinate along with the newly applied grass seed, and you'll have to do this all over again in a year or two?
  5. jeffinsgf

    jeffinsgf LawnSite Senior Member
    Messages: 641

    That assumes that the weeds are in a ripe seed head stage. Also, many of the weeds that you would be dealing with are not as likely to grow well in the fall, while cool season grasses will. There's no panacea. It is likely that getting the weeds out will be a multi year project, but tilling won't change that and might make it worse. Unless you are adding large amounts of soil amendment (compost and/or sand) or changing the grade, tilling seems like a lot of work for little gain to me.
  6. LarryF

    LarryF LawnSite Bronze Member
    Messages: 1,181

    Thanks for responding Jeff. I wasn't thinking of tilling the ground, but I do wonder about using a preemergence herbicide such as Lesco's Snapshot 2.5TG for annual weeds. That stuff is expensive and I'd rather not, but it seems to me that the weed seed could stay in the soil until next summer and start to germinate then. I admit that I don't really have much of a feeling for the "ripe seed head stage" that you refer to, but it seems to me they'll get to that stage evenutally unless something is done to prevent it from happening. I also don't know if the herbicide I mentioned would impact the grass seed I would be planting should I use it after killing the weeds with Roundup. In my case, my weeds are mostly crabgrass, veronic and I think carpetweed. And if it could impact the new grass seed, how long should I wait before seeding the grass?
  7. NNL&LS

    NNL&LS Banned
    from zone 5
    Messages: 88

    How large is your lawn? have you considered roundup, then sod?
  8. jeffinsgf

    jeffinsgf LawnSite Senior Member
    Messages: 641

    The packaging should tell you how long to wait. You might be able to get that from Lesco's website, too. Don't worry about the crabgrass you have now. It will be dead after the first frost. Seed now, get the grass established, then use preemergent in the early Spring. My yard was filled with crabgrass last year. I used a preemergent the first week of March and didn't see any crabgrass all year. The way to keep weeds from setting seed is to keep their heads cut off. That's a pain when they grow faster than the grass -- you have to mow based on the weeds instead of the grass, but that is the surest and cheapest way to kill weeds -- don't let them grow. Crabgrass can be the exception to that, because it will duck and throw a seedhead at 1-1/2 inches if it has to.
  9. TforTexas

    TforTexas LawnSite Senior Member
    Messages: 260

    Snapshot is not labeled for turfgrass areas. If you want to use a preemergant along with cool season seeding you can use Drive 75. I will offer pretty good pre emergant control plus post emergant on some species (Round up will have already taken care of that.) Seeding in the fall you will mostly germinate broadleaf weeds which can be taken care of once the new seed is up and mowed 4-5 times. Dimension, Barricadef or Pendimethalin in the spring will give you good control of the grassy weed. Remember starting over from scratch may cause you to have a year of "growing pains". Getting the new grass established and knocking back the new weed crop.
  10. LarryF

    LarryF LawnSite Bronze Member
    Messages: 1,181

    Thanks T, I now realize you are absolutely right about the Snapshot, and I hope I didn't steer anyone in the wrong direction by mentioning it. I had used Roundup and then Snapshot with good success on a pretty large (~5000 sq ft) mulched area where weeds had taken over the area, so the Snapshot label was in my mind. But looking again I see that one definitely doesn't want to use it on a lawn. Nonetheless, it sound like you are in agreement with my point that just killing this year's weeds with Roundup isn't going to really solve much unless you also do something to eliminate the weed seed that has already dropped into the soil; otherwise, the weeds will be back next year. I think your advice is good and I'm pretty sure I'll be taking it.

    In regard to the sod suggestion by NNL&LS, I haven't considered it and I don't think I will. I have about an acre of grass, but only about 15 percent of that has a weed problem. I think I can resolve it without resorting to having sod placed, and looking at the lawns of neighbors who have done that a couple of years back, they seem to now have lots of weeds too. I'm sure there are good reasons for using sod, but I'd skeptical that weed control is one of the predominant ones. But thanks for the suggestion, anyway.

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