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Overseeding and spring pre-emmergence applications

Discussion in 'Turf Renovation' started by thomaslawn, Feb 23, 2009.

  1. thomaslawn

    thomaslawn LawnSite Member
    Posts: 88

    I have a customer who wants a spring overseed and later a early spring pre-emmergence for weeds and crabgrass. What time frame do I need between these 2 applications? Thank you in advance for your help.
  2. Barefoot James

    Barefoot James LawnSite Senior Member
    Posts: 984

    Dormate seed asap - cover with a thin layer of compost. Seed needs to get down before about the 15th of March and hopefully if the weather cooperates you will have till about May 10th before you need to put down pre. They say crab grass starts to germinate after May 10th in your area. April 20th for us here in Louisville - so pre needs to get down by those dates or you can get germinating crab grass and other weeds. I would only use a half app and then the other half by the middle of June. This should keep the crab down and not hurt the new grass or just germinated seed.

    I have dormate seeded many yards already here. Never gaurantee any spring seeding as it is a complete crap shoot for actual grass germination rates - unless you are doing Bermuda or Zoyzia. For fescues, ryes and KGB's you are completely at the mercy of weather temps.

    Fall is the only time I can gaurantee it. Cause we are going to get the temps we need and with or without rain we can control the irregation. Spring seeding does need to be keep moist - but usually we get plenty of rain - it is the slow ground temp warm up that is the cause of irregular grass germination rates - especially wen getting it before the crab grass can.

    Good Luck
  3. tombo82685

    tombo82685 LawnSite Senior Member
    Posts: 288

    First off, your fighting one with the other. If you apply your crabgrass control then you cannot seed lawns unless you have like a scotts product or another product that still allows seeds to germinate. Crabgrass preventers put a barrier on the soil surface which wont allow crabgrass or any grass related species to germinate. So if your going to put premergence down make sure it still allows grass seeds to germinate, or just wait till fall to seed. In terms of when to apply crabgrass pre emergence they use a good general rule of thumb that is when your forsythia bush starts to bloom or is in bloom put down your crabgrass control. Crabgrass needs atleast 3 days of 50 degree soil temps or high before it starts to emerge. In terms of seeding, spring time is not the best for seeding but most people do it anyways. The reason why its not that great is because the soil temperatures are still very cold so it takes longer, and the competition with weeds germinating in spring. In your area I would recommend for applying seed about mid april
  4. Barefoot James

    Barefoot James LawnSite Senior Member
    Posts: 984

    tombo - I would not wait to get the seed in the ground for spring (april means you miss lots of opportunity to grow some grass). Granted fall is best and only reliable option but 2nd option is dormate seeding and allowing as much seed to germinate as possiable (take advantage of all the rain) before the drop dead date for doing pre - emergent. if you want to buy more time - cause it will cost you plenty - seed several times starting now and when May 10th rolls around use tupersan as the pre but which will give you till June 15th and then add about 3/4 dose of a regular pre like barricade. but tupersan cost a fortune but will allow the grass seed to germinate and keep crab away for about 30 days.
  5. tombo82685

    tombo82685 LawnSite Senior Member
    Posts: 288

    James, I guess its all climatology really. Just going by my general area, the soil temperatures are still very cold here and the root growth is doing nothing as well as the top growth. I saw he is from columbus oh, not being from that area but realizing they are colder then where Im from I was thinking early-mid april until the grass itself is growing. It also depends on what type of grass seed you put down. We all know if you put down poa pretensis your going to wait a 2 weeks before germination, but lolium species take 4-8 days to come up, with fescues a little after that. So grass species also has to be determined. At my golf course we use barricade and dimension.
  6. tombo82685

    tombo82685 LawnSite Senior Member
    Posts: 288

    also when applying grass seed either aerate the soil or scarify the soil dont just throw the seed on top of the soil that wont do anygood unless it falls in cracks or other holes
  7. Barefoot James

    Barefoot James LawnSite Senior Member
    Posts: 984

    Good advice - tombo

    I never had much belief in dormate seeding either until the University of Kentucky turf grass professor AJ Powell told me about it. It works much better to let the temps control IF and when it wants to grow the grass - so you have a better chance of having grass without crab. It can be much cooler than you think to grow fescues and even rye than what crab requires. Plus the fesue seeds are up on top where that days sun can make it pretty warm - while crab is down an inch or more. i also like to cover seed with about 1/16 (dusting of compost) this really gets the germination rates up and feeds the seedlings.

    I would recommend using a Turf Revitilizer Power Seeder to apply the seed. You can rent them at most Home Depots in OH - or get a 9hp one. they are awesome.
  8. tombo82685

    tombo82685 LawnSite Senior Member
    Posts: 288

    Yea its all determined by the weather. Like you said about the heating of the day warms the top of the soil, the cold of night can also freeze the top layer of the soil quickly. Good point, with the dusted compost over the seed. We use penn mulch or a fine wood chip mulch thats is finely pulverized up no big chips. The mulch aides in heat and holds in water to help the seed germinate quicker.
  9. humble1

    humble1 LawnSite Silver Member
    from MA
    Posts: 2,499

    Seed early, You can apply tupersan as a starter fert w/ crabgrass control product that you can still seed with. It is very expensive. The other option is to use a post emergent control later on after the new turf is established. Keep in mind that getting a thick stand of grass will help shade out the crab, you never see crabgrass grow in the shade, it likes it hot, and it loves the sun.
  10. Jason Rose

    Jason Rose LawnSite Fanatic
    Posts: 5,858

    Yes, A Tupersan product, they usually blend it with a starter fert (both expensive). Seed ASAP, and once it's growing well put your regular preemergent down. I recommend Dimension, as Pendi or Barricade are more prone to damage the roots. If you don't feel comfortable applying the Dimension yet, hit it again with the Tupersan 30 days after the first app. That's all the longer it usually lasts, 30 days.

    Best of luck, I despise spring seeding. I've seen it done and if it's seeded at a higher rate and fed well it CAN get estiblished and choke out most of the weeds. Still have to apply pre for the crab in the mid spring and still must spray for broadleafs once or twice...
    I see so many homeowners spring seeding, and it pretty much always ends up being a weed patch by summer. Spring is just tough because it takes so long to germ because of the low soil temps.

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