# Purple centipede and fertilizing quiestions



## Gibby (Apr 3, 2018)

I read that when centipede is purple it is a phosphorus deficiency by @Greendoc in a lawnsite thread. I have not put down any fertilizer this season yet, and was planning on doing it the next couple days. My front yard is almost all purple centipede but my PH is also 7.9 in that area.

I have been trying to decide on Milorganite or Ferti-Lome 15-0-15 for my first app, but the more I read the more I get confused.

Looks like I shouldn't use Milorganite as @Ridgerunner pointed out to @starkus in his thread because it has to much P, but I thought not enough P is what is causing it to be purple...

Looks like I shouldn't use Ferti-Lome 15-0-15 due to the fact that the it has 15% urea nitrogen.

Here is last falls soil test. Someone please help me choose a fertilizer, my head is starting to spin lol.


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## Gibby (Apr 3, 2018)

To make my head spin more, I contacted Super-Sod which is where the builder got my sod. And they recommended Starter and Centipede Formulation (5-10-30 + Iron) at 3 applications per year at 10lbs/1k.


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## Ridgerunner (May 16, 2017)

@Gibby 
What's the basis for your thinking that urea is not good for Centipede? The relationship between redish/purple leaf color is associated only with EXTREMELY low phosphorous deficiency. It can also be due to a hard frost or stress. Have you compared your test phosphorous ppm values to the low end sufficiency values for Mehlich 3?
P.S, my suggestions regarding P for starkus were based on HIS current soil levels. Centipede does not do well with higher levels of P, but that doesn't mean it doesn't need or use P.


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## Gibby (Apr 3, 2018)

Ridgerunner said:


> @Gibby
> What's the basis for your thinking that urea is not good for Centipede? The relationship between redish/purple leaf color is associated only with EXTREMELY low phosphorous deficiency. It can also be due to a hard frost or stress. Have you compared your test phosphorous ppm values to the low end sufficiency values for Mehlich 3?
> P.S, my suggestions regarding P for starkus were based on HIS current soil levels. Centipede does not do well with higher levels of P, but that doesn't mean it doesn't need or use P.


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## Ridgerunner (May 16, 2017)

I only did a brief search of Centipede today (so, it certainly wasn't exhaustive), but I didn't see any of the university (or otherwise) sites that cautioned against urea. (many, many recommended a 15-0-15). Who is grassdoctor? Do you trust his advice? The only thing that even remotely comes to mind is that Centipede is unusually sensitive to higher levels of NH4? That would leave you only with Nitrate fertilizer. If that is the issue, I would have expected some comment in the university recommendations. Please do the math and post your tested P levels, they do look like they will be lower than 26 ppm, maybe significantly.


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## Gibby (Apr 3, 2018)

Ridgerunner said:


> Who is grassdoctor? Do you trust his advice?


@Greendoc I think is the grassdoctor and if so, then yes.



Ridgerunner said:


> Please do the math and post your tested P levels, they do look like they will be lower than 26 ppm, maybe significantly.


Is this the correct math for the Front location?
(46 lbs/acre P2O5 x 0.5) x 0.4364 = 10.0472 ppm?


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## Greendoc (Mar 24, 2018)

Gibby said:


> I read that when centipede is purple it is a phosphorus deficiency by @Greendoc in a lawnsite thread. I have not put down any fertilizer this season yet, and was planning on doing it the next couple days. My front yard is almost all purple centipede but my PH is also 7.9 in that area.
> 
> I have been trying to decide on Milorganite or Ferti-Lome 15-0-15 for my first app, but the more I read the more I get confused.
> 
> ...


Going purple in Centipede is not a sign of Phosphorus deficiency. That is more likely a sign of stress from cold, chemicals, etc or else it is low Potassium. Going purple due to low Phosphorus is something I see in Zoysia.

Here's what I want to apply to Centipede. 1 lb per 1000 sq ft Ammonium Sulfate, 1/2 lb Potassium Nitrate or soluble Potassium Sulfate, 1 oz Ferrous Sulfate and a general soluble micronutrient mix. What I am applying is not based on what is cheapest, rather it is about what produces the most benefit to the grass without creating new problems. Now, maybe you can get away with spreading something where the Potassium is from Potassium Chloride because your ground is mostly sand and it rains over 40 inches per year and then snows on top of that. I have neither, so anything I put on the soil, I am stuck with it for years. 15-0-15. I am trying to figure out how that is formulated to have exactly that without some kind of filler. If I were to blend Urea and Potassium Chloride together, in a 50-50 ratio, that would be 23-0-30. I do not see low analysis, bulked up fertilizers in my state because shipping is so costly. I know it is a thing in the rest of the US. I have also read my share of specimen labels where limestone is used as the filler. Why are we putting lime on grass that wants a pH of 5.5. Now, if that fertilizer were bulked up with prilled sulfur, you are ok. My idea of a bulk blend granule for Centipede would look like 30% Ammonium Sulfate, 30% Potassium Sulfate, 25% prilled Sulfur and 5% Ferrous Sulfate.


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## Ridgerunner (May 16, 2017)

> Is this the correct math for the Front location?
> (46 lbs/acre P2O5 x 0.5) x 0.4364 = 10.0472 ppm?


46 lbs/acre of P2O5 at the 4" depth would be 69 lbs/acre of P2O5 at the 6" depth.
69 / 2 = 34.5 ppm of P2O5
34.5 ppm of P2O5 / 2.3 = 15 ppm of P (elemental)
or 
69 lbs/acre slice furrow of P2O5 / 4.6 = 15 ppm of P (elemental)
Gibby, plant reactions (color, deformities, etc) to nutrient excesses or deficiencies can exhibit themselves differently depending on the plant. I'm not an experienced warm season grass person, so I am uncomfortable guessing at what may be causing a color change in a Centipede grass. In fact, I wouldn't do that even with a cool season grass. I would rely on a tissue test, to determine a deficiency if all of my nutrient levels were already within sufficiency range.
I am more than happy to answer any questions you may have in understanding your soil tests, but diagnosing Centipede issues, is way out of my comfort zone.


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## Gibby (Apr 3, 2018)

Ridgerunner said:


> > Is this the correct math for the Front location?
> > (46 lbs/acre P2O5 x 0.5) x 0.4364 = 10.0472 ppm?
> 
> 
> ...


See my update here https://thelawnforum.com/viewtopic.php?f=2&t=2285#p44970

I am not going to worry too much about it right now.


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## Ridgerunner (May 16, 2017)

FWIW, there are plenty of people (many here on TLF) who grow absolutely beautiful lawns with both cool season grasses and warm season grasses in high pH soils.
Good luck with your builder, hope it works out.


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## Greendoc (Mar 24, 2018)

I have seen Centipede tolerate pH higher than 6 and look not bad. Those soils are also low P, have very little Chlorides or salts and are fairly well drained. Heavy clay + high salts and Chlorides tend to be the deal breaker for Centipede. In my state, the only places where Centipede does well is above sea level and relatively far from the coast. There are no beachfront lawns of Centipede grass.


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## Gibby (Apr 3, 2018)

So would a balanced fert like 10-10-10 be good idea?


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## Confederate Lawn (Apr 4, 2018)

Gibby said:


> So would a balanced fert like 10-10-10 be good idea?


I watch a guy on youtube (The Lawn Care Nut) and he swears by Milorganite and a 10-10-10 as a starter fertilizer. I too have purple centipede which everyone is telling me its actually carpet grass. I don't know enough about grass types to be sure so I'm treating it like centipede. I did milorganite almost two weeks ago and things are noticeably growing! I have some St. Aug under a tree that is taking off. Also the carpet grass (my idea of purple centipede) is thriving as well, but it's purple :?


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## Mightyquinn (Jan 31, 2017)

I think the high pH and the cold temps are what is causing the Centipede to look purple. I do like Greendoc's plan of using acidifying fertilizers for the high pH as it should get you the best results. Spoon feeding it is probably the best way to go as from some research I've done in the past on Centipede lawns they prefer LOW pH soils, hate Phosphorus and only require about 1.5 lbs/K of Nitrogen a year. Adding a little iron to the mix will help it with maintaining a darker green color too. @Gibby I curious why you have such a wide range of pH in your lawn? Having 2.0 points of pH difference is definitely odd to me


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## Ridgerunner (May 16, 2017)

> @Gibby I curious why you have such a wide range of pH in your lawn? Having 2.0 points of pH difference is definitely odd to me


That's a very good question. (I thought those 6s as 8s)


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## Gibby (Apr 3, 2018)

Mightyquinn said:


> I think the high pH and the cold temps are what is causing the Centipede to look purple. I do like Greendoc's plan of using acidifying fertilizers for the high pH as it should get you the best results. Spoon feeding it is probably the best way to go as from some research I've done in the past on Centipede lawns they prefer LOW pH soils, hate Phosphorus and only require about 1.5 lbs/K of Nitrogen a year. Adding a little iron to the mix will help it with maintaining a darker green color too. @Gibby I curious why you have such a wide range of pH in your lawn? Having 2.0 points of pH difference is definitely odd to me


I think it is where the builder brought fill in our something. The places where the PH is high, the soil is also more compacted.


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## Mightyquinn (Jan 31, 2017)

Gibby said:


> Mightyquinn said:
> 
> 
> > I think the high pH and the cold temps are what is causing the Centipede to look purple. I do like Greendoc's plan of using acidifying fertilizers for the high pH as it should get you the best results. Spoon feeding it is probably the best way to go as from some research I've done in the past on Centipede lawns they prefer LOW pH soils, hate Phosphorus and only require about 1.5 lbs/K of Nitrogen a year. Adding a little iron to the mix will help it with maintaining a darker green color too. @Gibby I curious why you have such a wide range of pH in your lawn? Having 2.0 points of pH difference is definitely odd to me
> ...


Does it look different or have a different composition than the lower pH soil?


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## Gibby (Apr 3, 2018)

Mightyquinn said:


> Gibby said:
> 
> 
> > Mightyquinn said:
> ...


I think it looks darker, the lower PH parts are mostly sand.

I'll check once I get my gogo juice in me.


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## Gibby (Apr 3, 2018)

Mightyquinn said:


> I do like Greendoc's plan of using acidifying fertilizers for the high pH as it should get you the best results.


Thanks for dumbing it down for me as I did not get that from his post but now it makes a lot more sense.


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## g-man (Jun 15, 2017)

I really think you need to treat the front and side2 different than the side1 and back. It is a different soil. For example: calcium is different, the TEC looks different and the very big difference in ph. The difference in pH will also affect the availability of nutrients. I'm a cool season guy with a high pH soil, but I have not experience with Centipede. If centipede wants a pH of 5, I dont see how an 8.1 pH will help.


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