N-P-K what to use and when?

Old 05-10-17, 05:59 AM
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N-P-K what to use and when?

My question is (aside from whatever a soil test might tell me, which I'll be doing shortly), how come some people swear by a 4 step program which varies the NPK during the season, and some people swear by just using one product 4 times a year (such as Milorganite)?

Overall, my lawn is pretty decent, I of course want it a little better, but would generally be happy maintaining it as it is. I plan to aerate and overseed in the fall.

Should I be using a 4 step, or just something like Milorganite all year?

I've come across the following products which, aside from being organic (which I like), all get really good reviews everywhere I look, but are very 'limited' in their NPK:

Safer Brand 25 lb. Ringer Lawn Restore II Fertilizer 10-0-6, $147
Purely Organic Products 25 lb. Lawn Food Fertilizer 10-0-2, $101

Milorganite 36 lb. Organic Nitrogen Fertilizer 5-4-0, $104
GreenEdge 40 lb. 6-2-0 Slow Release Organic Fertilizer 6-2-0, $173

I guess I'm mainly confused as to how these 4 products do so well all year long, when two of them have no P and two of them have no K.

Thanks for any help!
Old 05-10-17, 06:08 AM
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Why pay so much for something you throw out on the ground? Use agricultural fertilizer of the NPK analysis you choose.
Old 05-10-17, 10:06 AM
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It all depends on what you are trying to accomplish and how much work/thought you are willing to invest. Simply slinging out 10-10-10 a few times of year doesn't hurt. It makes a lawn greener and it's easy since you don't really think about it or buy anything special. But it's not optimal. Plants need different nutrients during different phases of their growth. Spring with rapid growth takes a lot of one component but in fall plants will need different nutrients to fortify their roots to withstand winter.

For increased work you could bother to getting a fertilizer that more matches what's needed at that time. In early spring for example you'd be throwing out something quite high in nitrogen. Come fall and you might be applying something low in nitrogen but higher in other nutrients.

Why do products of varying specs all work so well??? Consider that the plants will likely survive and do quite well without any help from you. Fertilization in many cases is not needed and adding the wrong stuff usually does no harm so adding fertilizer is generally a safe bet. Add the right fertilizer and you get the most bang for the buck. Add an incorrect fertilizer will produce positive results in most cases but you may have spent a lot of money for minimal or not optimal improvement.
Old 05-10-17, 11:41 AM
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Thanks so much and this is really the root (pun intended) of my main question "Plants need different nutrients during different phases of their growth."

If that's indeed the case, why do so many people swear by just using Milorganite all year long? Wouldn't it be better to use some kind of 4 step type program (whether Scotts, Lesco, whatever) that better matches the NPK to the season)?

For example, I do a fall seeding, so Lesco would recommend something along these lines:

19-0-7 in March/April
18-2-9 in April/May/June
24-2-11 in July/August
18-24-12 + Seed in September
18-0-18 in late Oct/November

Is this type of program a LOT better than just keeping it easy/simple with Milorganite 4 times a year?

I just always question why so many people give rave reviews to Milorganite (and other organics mentioned above) when in theory it should work better to match the NPK to the season.

And, again, the organics always have 0 as either P or K, so how can they work nearly as well as something that (at least at some time during the season) has a value in each category?

Finally/on a related note, if I were to just go organic, would you guys recommend the ones that have no P or no K?

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