Best N-P-K for fall application?

Discussion in 'Pesticide & Herbicide Application' started by griffy77, Oct 31, 2005.

  1. griffy77

    griffy77 LawnSite Member
    Messages: 102

    I had I always thought that in the fall that you should you use a lower Nitrogen level and higher Phosphorus and Potassium. With grass preparing to go dormant i dont see why you would want to increase N since that helps promote growth. I like to feed the roots with P and help vigor with K to help survive winter better.

    The guy at Lesco told me that all the golf courses order 32-8-4 now. The idea is that the plant builds up N then uses it up in spring to encourage greener lawns.

    Would most of you guys agree with Lesco? What NPK are you guys using and why?
  2. SchlepRock

    SchlepRock LawnSite Member
    from Ohio
    Messages: 10

    I agree with the higher P & K on the last visit. In some cases, you can overdo the Phos and you should probably test.

    Using high N just before the plant stops growing does increase carbohydrate storage for winter and allows for early spring green up.
    Think about it, at the beginning of the route, much of the N will be used up. But since they will be the first ones done in the early spring, it works out.
    The last ones done in the fall need the early green up since you may not get there until later in the spring.
  3. lilmarvin4064

    lilmarvin4064 LawnSite Senior Member
    Messages: 757

    I like 25-15-10. K levels already pretty good round here.:blob3:
  4. EJK2352

    EJK2352 LawnSite Bronze Member
    Messages: 1,150

    I like a 20-10-10 w/ 50% scu for my early fall apps.
  5. teeca

    teeca LawnSite Bronze Member
    Messages: 1,202

    46-0-0 set at the 2.5# per 1k rate.. this helps build the carbs, great spring green up, and most of all..... a very large $$$ application.
  6. ThreeWide

    ThreeWide LawnSite Bronze Member
    Messages: 1,116

    It seems there are different theories on the last Fall application. However how this is handled depends largely on the type of turf as well.

    With Bermuda, my last application of the year has high Potassium to help with Winter stress from cold temps. If the lawn is deficient in Phosphorous, I would use a 9-23-30 for example. Otherwise, 8-2-34 would be the choice.

    I'm not a believer in applying high N during the last application. It causes top growth when the plant is in the process of storing carbs for dormancy. By pushing N, you interfere with natural processes.

    And Timturf will be quick to point out here that the use of SOP for your Potassium was proven to provide faster greenup the following Spring.
  7. Tscape

    Tscape LawnSite Bronze Member
    Messages: 1,370

    You have got to explain the 50% SCU to me. For the life of me I can't understand this.
  8. Killswitch

    Killswitch LawnSite Senior Member
    Messages: 438


    Lots of wild answers.

    The right answer is 16-0-31 at 2 to 3 lbs per K
  9. AlpineNaturescapes

    AlpineNaturescapes LawnSite Member
    Messages: 149

    Completely depends, when you fert, and where you are ferting. In more arid areas, the soil usually has plenty of K and P. I usually don't use much of it unless a prop has been neglected.
  10. GrazerZ

    GrazerZ LawnSite Senior Member
    Messages: 670

    This is one of the old great debates I'm told. Personally it depends on the lawn and whens my last application. I do not believe in a one size fits all aproach. For example if I'm doing a lawn that requires a early fall app,(sept) then I will use higher N content but with higher Slow release (poss a 32-0-10 75%scu 2% fe)
    if the lawn is a later fall application then I swich to a 20-0-20 50% scu 2%fe). And if its a really late application, say first to second week in Nov and the cold is comming on strong, I will switch to a 16-0-31 or therebouts. I don't want to push the N late in the fall. Here, the grass is naturally slowing down its growth anyway, there is no need for alot of top growth. Typically the falll lawns are always my favorite, Little stress, optimum growing temps, they look great.
    I guess if you look at the awnsers, I'm somewhere in the middle of the debate.

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