Please explain NPK in a detailed way.

Guys

So I run a SOG grow with fully rooted cuttings put into flower at about 2-3" in height.

Unfortunately, for some reason or another they were suffering from a nitrogen deficiency (stunted growth, purple stems and yellow leaves).

What I really need to understand (as a professional plantsman, it has never been explained properly) is this:

My organic Canna flower fertiliser is 2.5-2.5-5 NPK. I use this for every other water. So if I add an organic nitrogen based fertiliser of say 6-2-3 will that make the over all feed 8.5-4.5-8.5 ??? Or does it not work like that?
Because if it does then why aren't fertlisers made at 15-15-45 or something similar??? I NEED TO UNDERSTAND!!!

I really want to lock down my understanding of the mathematics behind the whole NPK thing so if someone of extreme knowledge wouldnt mind taking a few minutes...

Kindest and warmest regards, without this I would be lost.

Thanks
plantsman

This thread was a result of a search I did so sorry to dig it up. =)

Interesting question plantsman. I don't have a definitive answer but do have an educated guess.

I would say by mixing the two the highest numbers from each would be the new n-p-k

6-2.5-5

Each has it's own concentration by volume so an increase would need to be done during manufacturing.

Yeah, I've always wanted to know why if some are 2-2-2 and others 4-4-4... what's the actual difference between the two? Is it a firm ratio in that 4-4-4 is twice as concentrated as 2-2-2? And what are these measurements in... 2 and 4 what? PPM or something similar?

Things that make you go Hmmmmmmm.

You actually will find nutrients that have an NPK rating of 15-15-50 or something similar.

There are soooo many companies that make fertilizers out there and they make them for every different type of plant that you can imagine. It is not really about how much NPK value you have but how well it is taken in by the plant.

You have to understand that plants do not really require added nutrients to survive. Sufficient light, soil, and water is all a plant really needs to survive so adding these extra nutes is just giving them a bonus to get bigger. If you think about it though, outside plants will get these extra additive nutes from the soil, decomposing plants leave everything in the earth after they die.

So, if you are growing indoors with soil or hydro then all you want to do is find a happy medium where you can add just enough nutes so the plants can thrive. I personally think that you should stay away from anything that is a general NPK value, so a 20-20-20 is just not specific enough to get what you really want out of a plant. I used to say that plants will take any kind of Fertilizer and love it but that is simply not the truth. Find a good product like Techniflora, Fox Farm, Advanced Nutrients, etc. and run with it. These companies have basically and inadvertanly created products that are PERFECT for growing marijuana!

And if you pay close attention they use natural ingredients to make the product. A lot of Kelp, decomposed veg, fish manure, etc. will be soluable to the plant much easier than a chemical based blue/ crystally product.

Of course some plants can take more nutrients than others! So, you REALLY need to experiment and find a good level of nutes to give to your plants because only you know what your growing conditions are!

I could sit here and tell you how I do things all day but you need to figure it out for yourself, I have no idea what your grow area is like so it is kind of hard to give Specific advice

SableZen said:

Yeah, I've always wanted to know why if some are 2-2-2 and others 4-4-4... what's the actual difference between the two? Is it a firm ratio in that 4-4-4 is twice as concentrated as 2-2-2? And what are these measurements in... 2 and 4 what? PPM or something similar?

Things that make you go Hmmmmmmm.

Click to expand...

It is ALWAYS measured in parts per million!

So naturally a 20-20-20 is going to be stronger than a 5-5-5.

And if you are going to use a "General" product like that then go for the lower numbered one.

You can always add more but it is a BITCH to take the nutrients out!

plantsman said:

Guys

So I run a SOG grow with fully rooted cuttings put into flower at about 2-3" in height.

Unfortunately, for some reason or another they were suffering from a nitrogen deficiency (stunted growth, purple stems and yellow leaves).

What I really need to understand (as a professional plantsman, it has never been explained properly) is this:

My organic Canna flower fertiliser is 2.5-2.5-5 NPK. I use this for every other water. So if I add an organic nitrogen based fertiliser of say 6-2-3 will that make the over all feed 8.5-4.5-8.5 ??? Or does it not work like that?
Because if it does then why aren't fertlisers made at 15-15-45 or something similar??? I NEED TO UNDERSTAND!!!

I really want to lock down my understanding of the mathematics behind the whole NPK thing so if someone of extreme knowledge wouldnt mind taking a few minutes...

Kindest and warmest regards, without this I would be lost.

Thanks
plantsman

Click to expand...

OHSOGREEN knows all that stuff.I would post stuff like that in Organics... or search his name.good luck

NPK is the percentage (by weight) of each element in the fertilizer.

Example:

A 100lb bag of fertilizer with the NPK values of 25-15-20 mean that there is 25lbs of nitrogen, 15lbs of Phosphurous, and 20lbs of Potassium.

Anonymiss1969 said:

NPK is the percentage (by weight) of each element in the fertilizer.

Example:

A 100lb bag of fertilizer with the NPK values of 25-15-20 mean that there is 25lbs of nitrogen, 15lbs of Phosphurous, and 20lbs of Potassium.

Click to expand...

So would that equate to higher NPK values being a more pure product? I would assume in your example (25-15-20) that 60% is usable fertilizer and 40% is filler of some sort (probably water)?

Also, I'm a little buzzed right now so can't figure this out, but does your answer mesh with the PPM answer as well?

Also (lol), I would assume that a theoretical 25-25-25 fertilizer would end up being mixed with twice as much water as a 12.5-12.5-12.5 fertilizer? Or is there no corrolation between the numbers and amount of water dilution?

SableZen said:

So would that equate to higher NPK values being a more pure product? I would assume in your example (25-15-20) that 60% is usable fertilizer and 40% is filler of some sort (probably water)?

Also, I'm a little buzzed right now so can't figure this out, but does your answer mesh with the PPM answer as well?

Also (lol), I would assume that a theoretical 25-25-25 fertilizer would end up being mixed with twice as much water as a 12.5-12.5-12.5 fertilizer? Or is there no corrolation between the numbers and amount of water dilution?

Click to expand...

Well you have to take into consideration that whether youre using organic or chemical, the Nitrogen isn't going to be pure Nitrogen, Phosphorus, or Potassium, it will most likely be a Nitrate (NO4), Phosphate (PO4), or Potash (K2O). This means that some of the weight of the fertilizer is oxygen (or some other element that is combine with the NPK's to make them more stable).

SableZen said:

So would that equate to higher NPK values being a more pure product? I would assume in your example (25-15-20) that 60% is usable fertilizer and 40% is filler of some sort (probably water)?

Also, I'm a little buzzed right now so can't figure this out, but does your answer mesh with the PPM answer as well?

Also (lol), I would assume that a theoretical 25-25-25 fertilizer would end up being mixed with twice as much water as a 12.5-12.5-12.5 fertilizer? Or is there no corrolation between the numbers and amount of water dilution?

Click to expand...

I forgot to answer some of your questions...

I don't believe the PPM answer was correct, but I'm not claiming to be all knowledgeable on fertilizer.

A fertilizer with half the NPK value would mean theres 2x as much filler or other elements, but not necessarily 2x as much water. I would assume they take the NPK before they hydrate the fertilizer.