NPK-- whats the deal?

Okay, so I see one fertilizer at the store thats like 30-15-15 and another right next to it thats 2-1-1. Is the 30-15-15 really 15x stronger than the other? Do I need to use 15 times more of the 2-1-1 to equal a dosage of the other? If i do, will I end up burning my plants with whatever other micronutes and stuff is in it? I'm starting to think that 2-1-1 is the ratio from N to P to K, rather than the percentage of volume in the whole container.

PuffinLikeAPimp said:

I'm starting to think that 2-1-1 is the ratio from N to P to K, rather than the percentage of volume in the whole container.

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It's both.

A 2-1-1 and a 30-15-15 are both the same ratio.

It's also volume. Say both are in 100# bags. The first would be 2# of N and 1# each of P&K. The second would have 30#of N and 15# each of P&K and much easier to burn your girls with.

Wet

thanks. so you suggest going with the 2-1-1 and just adding more?

The N-P-K numbers that are printed on the package of nutrients or fertilizer indicate the percentage of "those" elements (by wieght) that the product contains "As Is". By "As Is" I mean before being mixed, diluted, or spread out in any way, shape, or form - just as it sits, in the package!

Somewhere on that package you will find a section that reads "How To Use" (or something like that). Basically, these are the directions that tell you how much of this product to "mix in", with water or "soil", for diferent applications. It is this "Mixing" of the product that determines the actual, final, strength or potency of the product that the plants are exposed to.

Here is a perfect example! I have two different, 4 lb., packages of "Organic Fertilizer". Both are made of "similar" ingredients (a combination of various organic meals and composted manures or guanos). The main, appearant, difference is that one of them has N-P-K numbers about twice as "Strong" as the other:
Whitney Farms "All purpose" Fertilizer (5-5-5).
FoxFarm "Marine Cuisine" Fertilizer (10-7-7).
The "real" difference is in the directions on the packages. Whitney Farms says to use twice as much product per gallon of soil (2 Tblspns.) as opposed to FoxFarm (1 Tblspn.) per gallon of soil. Following this example, the Whitney Farms product actually delivers about 30% more P&K (but the FoxFarm product "goes farther").

To make a long story short, "It's all about how much you mix in - not just what the N-P-K numbers say!".

Great. Think i get it now. Its all about how much you use and the ratio, not as much the percent of weight. So my organic 2-1-1 says to use 1 tblsp evry other time you water, while the 30-15-15 says to use it once a month, its effectively the same. Do organic liquid ferts also contain trace nutrients? Or is the other 97% of the solution water? Im not sure if i should get a trace nutrient supplement or not. Opinions? Experiences?

Most products don't furnish adequate information on secondary nutrients (Sulphur, Calcium and Magnesium), let alone the other Trace Elements! As I understand it, it is just assumed that a "good" soil mix will contain enough everything except N-P-K!

That, kind of, sticks in my craw! And lately, I've been on a "Mission" to find out just how much secondary nutes and trace elements cannabis needs. I have recently sworn-off, "Big Name" products and switched to mixing my own organic stuff. I have found a ton of information about N-P-K but almost none about the "rest of the team".

Oh yeah, almost forgot - the other 97% is probably just water and "filler", maybe some Secondary Nutes!

I should think that Hydroponic nutrients would have a "Full Dose" of all required nutrients, but anything meant for soil is more "iffy".

True... Well I got the hydroponic liquid stuff that you add monthly with watering. Plus, my soil mix probably has some secondary nutes. I just wasn't sure if thatd be enough. I know some brands have secondary nutrient complexes. I'd just rather not shell out another 15 for something gold ol' dirt has anyways. Thanks a bunch T.H.Cammo, it's confusing stuff