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A Beginner’s Guide To NPK In Hydroponics

What does NPK stand for? If you’ve ever bought any fertilizer or nutrient solution, you will see these three numbers clearly displayed somewhere on the packaging. That stands for nitrogen, phosphorus, and potassium. N, P, and K. If you paid attention during high school chemistry you should hopefully know this. So these three numbers here represent the percentage of nitrogen, phosphorus, and potassium that is available in this fertilizer.

These three numbers will always be in that same order of N, P, and K. And should be clearly displayed on just about any fertilizer you will buy. Will every nutrient solution come with all three of these nutrients include? It is for a complete and balanced fertilizer.

But this is not always the case. Frequently you will often see blooming fertilizers which will have no nitrogen at all. So they will just display a big fat zero for that first number. Nitrogen, phosphorus, and potassium. These are known as the three essential macronutrients for plant growth. Without these, your plants will not be able to thrive. 

Benefits Of These Nutrients For Pants

  1. Nitrogen, that is the green up nutrient. This is what makes your plants green. It makes them grow big and it makes then grow strong. Nitrogen is listed first because it is the absolute most important nutrient in your solution.
  2. Phosphorus, it is essential for blooming. It helps with all reproductive phases of your plants. So if you want a lot of blooms, a lot of flowers, if you want to produce a lot of fruit or a lot of seed, you want phosphorus in your solution.
  3. Potassium, it plays a very essential role in plant photosynthesis, as well as CO2 uptake and activation of plant enzymes. As well as regulating water uptake within the plants. It is also essential for building strong healthy stems, as well as producing strongly viable seeds.

Since they only list these three numbers, N, P, and K on the front of your bottle of nutrient solution, you may think that these are the only nutrients that your plants need. Unfortunately, you would be wrong. There are several micronutrients which play pivotal roles in the production of plants. They are just used in much smaller quantities, not anywhere near as much as N, P and K. That’s why they concentrate on these. But most complete and balanced fertilizer solutions will also contain other micronutrients and other elements in the solution for complete and total plant growth.

You may notice that these three numbers do not add up to a hundred percent. These are percentages of your solution. So what is in the rest of your solution? If you’re using a liquid, a lot if it’s water. You gotta have a carrier agent for these nutrients. Also, there are the essential microelements. That makes up a portion of the solution as well. Another thing to bear in mind is that these are not pure elemental forms of nitrogen, phosphorus, and potassium. It has to be available in a form in which the plant can take it up.

So there are other elements and other weights that are combining to make up the rest of this solution. For example, if you look at phosphate, it is listed as the phosphate molecule, not pure elemental phosphorus. It is P2O5, is the actual molecule that plants are using to take up.

An important thing to note is that there are several different sources for these nutrients. If you look at the back of this bottle of Dyna-Gro, for example, there are actually two sources that makeup that 9% nitrogen. There is 2.9% ammoniacal nitrogen, which as you can imagine, would be ammonia derived, and then there is 6.1% nitrate nitrogen. Just to reiterate, these are not pure elemental formats of these nutrients, there are several different molecular compounds that can be used to supply these essential nutrients to plants.

Quality Of Nutrient

The quality of that nutrient will depend on which compound is used, and using which compound for that nutrient will vary greatly depending on what you’re end goal is, Whether you’re in soil or hydroponics, and many other factors. So a source like Dyna-Gro is synthetically derived. You may be wondering to yourself if there is an organic option. The answer is yes, there is, but there are some trade-offs with going organic in a hydroponic setup. Some potential trade-offs with organics are that you need a very strong microbial community in your nutrient solution. The microbes are what drives organic growing, they cycle the nutrients and make them available in a format that plants can use, much like these nutrients in a synthetic solution are already available in that format.

So if you don’t have a strong microbial community an organic solution really won’t work for you. Another drawback of it is it takes time to the culture that microbial community. So if you go organics, it’s always recommended to let your reservoir set up and culture and begin to cycle those nutrients so that by the time you do have plants into your system, the nutrients are available for plants. If it has not had time to culture and cycle those nutrients, there will basically be no available nutrient for your plants.

One final drawback of organics and hydroponics is some solutions do stink. Putting a highly microbially active solution into water, you can wind up with lots and lots of anaerobic microbes that produce horrible, horrible smells in your grow room. I know this from experience. If you’ve spent any amount of time looking at fertilizer or nutrient solutions, you’ll notice that these numbers that they display on the package can vary quite a lot.

So what does that all mean? How do you know what you need to grow what you want to grow? The solution is actually quite simple. What we have here is Dyna-Gro Foliage Pro. It’s what we like to use a lot for lettuce, greens, anything leafy producing a lot of green growth. And if you were paying attention earlier you’ll notice I said nitrogen is essential for green leafy growth.

If you look at the numbers on here, 936. Nitrogen is your nine, it’s the highest in concentration there. High in nitrogen fertilizers are essential for producing lots of green leafy growth. That is mostly what you will be using in a ZipGrow system. If you look at our lettuce formula, however, you will notice it is very high in phosphorus and potassium.

And if you have any knowledge on growing you might say, Ethan, this looks like a bloom formula for flowering and fruiting plants. Why would you use it on something green and leafy like lettuce that you don’t want to bloom, you don’t want to produce seeds, you don’t want to produce flowers? The answer with this is, it is used as a two-part solution in our auto dosing system. So we will actually supplement this base formula with calcium nitrate, which provides the calcium as well as additional nitrogen.

So that reason alone is why you may see some nutrient solutions which may not have any nitrogen at all in them because you are supposed to supplement it with a two-part solution. Also with blooming, nitrogen isn’t super essential, so when plants get into a blooming phase they need lower concentrations of this. Some manufacturers may choose to not put any it at all.

So if there is any confusion on what is a good idea for what you want to grow, just remember high nitrogen is good for greens, leafy vegetables, and lettuce, anything like that. High phosphorus, high potassium is essential for flowering and fruiting plants like vegetables. A lot with understanding what the basic N, P, and K, nitrogen, phosphorus, and potassium ratios are in your fertilizer or nutrient solution.

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