How soon before aerating and overseeding should I kill weeds?

Discussion in 'Turf Renovation' started by speedster, Jun 17, 2010.

  1. speedster

    speedster LawnSite Member
    Messages: 220

    I have a nasty section of my yard that must be 80-90% weeds. Not to mention it is compacted clay and very rough and clumpy. I want to get this section under control so that it can be nicer next summer. It obviously needs aerated and seeded. I was going to spray some type of weed killer like Weed-b-gone max to kill the weeds and then aerate the lawn followed by a good seeding. Being in WV I suspect I'd do the overseeding in mid to late september. How long after applying weed killer will I be able to overseed?

    Any recommended products for killing the weeds? There seem to be many species of broadleaf weeds along with crab grass and clover. It's horrible.
  2. bigslick7878

    bigslick7878 LawnSite Senior Member
    Messages: 809

    If it is that bad you might as well kill the entire section.

    Spraying will work with moderate weeds but if it is almost all weeds you are probably wasting your time and they will come right back when you overseed.

    It takes a good month for the weeds to die off either way.
  3. speedster

    speedster LawnSite Member
    Messages: 220

    thanks. what product would you recoomend to kill everything off?
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  4. ChiTownAmateur

    ChiTownAmateur LawnSite Senior Member
    Messages: 386

    slick knows better than me, i'm an amateur, but i think i have a pretty simple idea what you'd do here:

    1) Buy some Round-Up, a big container.
    2) Spray onto all the weeds thoroughly. It works only on the green leafy matter, so focus on covering all of it. DO NOT SPRAY ANY NEARBY GRASS! It will die just the same.
    3) Leave the plot with the dead material sitting there for now.

    By doing 1-3, you have killed the weeds and prevented them from spreading. By leaving it "as is" you should not have a big weed problem there until fall for overseding.

    4) In Fall, 3 weeks before you would be ready to overseed, rototill up the compacted area and incorporate some quality amendments. (topsoil, CORRECT type of compost, etc.). Water dirt -- seriously, a little bit for the next few days.
    ( 4a) Optional easier, worse results version:Simply Round-Up again right now, wait two-three weeks and then aerate and seed. )
    5) After rototilling, rake area smooth, roll with roller or compact down somehow. water dirt again, for a few days to get weed seeds growing.
    6) Wait 2 weeks, then Round-Up entire area to kill off weed seeds stirred up by rototill.
    7) One week later seed and cover with some form of mulch.
  5. speedster

    speedster LawnSite Member
    Messages: 220

    Thanks for the advice. #6 you said to apply Roundup one last time. Then in #7 you said to seed a week later.

    Having never used roundup is it safe to overseed that soon after applying roundup? I always tuought I had to wait 4 weeks after applying weed killer before starting seed. Something to do with the seed not germinating properly?
  6. bigslick7878

    bigslick7878 LawnSite Senior Member
    Messages: 809

    Like Chi town said the round up works only on the leafy part of the plant, it does not get in the soil.

    You could spray and then seed a week later especially if the weather is warm ( the hotter it is the faster it works)

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