New grass turning yellow . . .

saabmanSeptember 5, 2009

Front yard was aerated, the weedy parts rounduped, and later topped dressed with enriched organic dirt. I seeded and applied Scotts Starter Fertilzer. 2 1/2 months later, lots of watering, 95% of yard looks great EXCEPT a half moon area on other side of walkway from rest of yard.

Last week this area has gone from lush green to a bit of yellowing throughout. On recommendation of a landscaper a month ago I reapplied Starter Fert about 5 weeks after seeding and only this area is now suffering a bit. There could have been some overlapping of fert as this area is not large.

Is this a nitrogen deficiency, have I over-watered, or over fertilized? I thought I do 2 more ferterlizer applications -- Sept and later Oct-- before winter per Scotts instructions for midwest location. Not sure what to do. Grass is nice and thick and don't want to ruin what I've achieved.

pic available for looksee at

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Where do you live? What kind of grass do you have? Have you had a soil test done? If so, what were the results?

How often are you watering and how much water are you putting down?

I'm not sure I understood what you did with the second fertilizer application and where the lawn is suffering after that. Are you saying that the area where you applied the fertilizer is suffering and the rest is not? If so, you probably overfertilized.

    Bookmark   September 5, 2009 at 1:12PM
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I live in SE Wisconsin. Water 10-12 minutes every day when no rain. Extremely dry July here and early August. I didn't fertilize when I seeded because I used enriched organic soil. Lots of nitrogen. Then every 4-5 weeks I used Scots Starter Fertilizer so not to over nitrogen. Same routine over entire yard just this one area is yellowing. Picture tells the tale.

    Bookmark   September 5, 2009 at 4:58PM
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garycinchicago(Z5 Chicago IL.)

> "Water 10-12 minutes every day when no rain"

Problem solved, cased closed.

    Bookmark   September 5, 2009 at 5:58PM
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case closed? Then why isn't the rest of my yard the same?

    Bookmark   September 5, 2009 at 10:08PM
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You'd be better off watering less frequently and watering more deeply when you water. Watering often encourages shallow roots and also helps germinate weeds.

If you've been applying starter fertilizer regularly, you could be upping the P and K above where it should be and that could be interfering with the uptake of some nutrients.

Did you apply more fertilizer in the area that is yellowing? If so, that could be a contributing factor.

Another thing that could be happening is that the pH may be higher near the driveway because of leaching from the concrete.

One problem with trying to diagnose a lawn over the internet is that a symptom like yellowing can be caused by many different things. Too little water, too much water, too little iron, high pH, low pH are all things that can cause grass to turn yellow. As you can see, some of the causes can be opposites, so without more information, we could tell you to do something that would make it even worse.

Have you had a soil test done? That would probably be the first step. Find out if the University of Wisconsin does soil testing. If so, get the soil test kit and follow their directions. However, one change I'd suggest is to actually get two tests. For one, mix soil from various places around the lawn where the grass is doing well. For the other, get all the soil from the area where it is yellowing.

    Bookmark   September 5, 2009 at 11:09PM
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Thx for the response. I had a soil test done before any lawn work was done and all was normal. The only negative was a slight lack of nitrogen. I'll do another soil test on this small area to see if something is amiss.

    Bookmark   September 6, 2009 at 11:25AM
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andy10917(NY 6a)

"Normal" on the soil test is almost meaningless. Get a good test including micronutrients, and search on the web for someone that can help you interpret the nutrients and micronutrient levels. I've had dozens of people that got "normal" readings that then called and asked for the specific test values only to find out that they were deficient. They will give you a "normal" reading for Iron (Fe) at 2 ppm, but that level can easily cause Chlorosis. UMASS has an excellent set of tests and does testing for anyone in any state. Get the full test including micronutrients. If they send levels like "normal", call and ask for the specific levels.

    Bookmark   September 6, 2009 at 2:28PM
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Nitrogen will always show as low because it doesn't stick around in the soil.

Your soil tested in the normal range before you started, but since then you've been adding starter fertilizer (at least twice, but you also said every 4-5 weeks without saying how many times). You also hinted that you may have over-applied in some areas. So you could have raised the P and K too high and that could be interfering with the ability of the grass to use some nutrients.

If you have enough P and K in the soil, there's no need to keep adding them, especially if you mulch mow. Nitrogen will get used up and will wash out of the soil, but the P and K stick around.

    Bookmark   September 6, 2009 at 3:07PM
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re soil test . . . it was done by UW. 3 pages of readouts. Summary conclusion was all was "normal" . . . ph, P K and a host of other stuff except for need for N.

2x in 10 weeks with starter fert is not overdoing it but the response that P and K getting to high is interesting. I do bag clippings BTW. What's interesting is that I helped my neighbor reseed a 4 x 10 feet area-used the organic dirt but never used any fert at all. Checked it yesterday and it too is yellowing.

Landscaper says I should you milorginite now. I think he's guessing.

Anyway, thanks for the feedback. People actually read this stuff!

    Bookmark   September 6, 2009 at 4:00PM
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The landscaper is probably recommending milorganite for the iron and also for the nitrogen. A new lawn needs more nitrogen than an established lawn does. The N in milorganite is slow release and the iron will help if you're low in iron and/or if you've got an imbalance that makes some of the iron less available.

I wasn't sure if you had added fertilizer more than the two times. I guess I don't really understand why you're adding more P and K if the soil tests show that it isn't needed.

    Bookmark   September 6, 2009 at 4:41PM
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