Beyond Soil: My Guide To Hydroponic Fertilizers & Nutrients

Confused about hydroponic nutrients? Not sure about the difference between one, two and three-part solutions?

Don’t worry, but know this.

You must use specially formulated liquid nutrients for your hydroponic garden. It is non-negotiable. Unlike soil, water has no nutrient buffer and everything your plant needs has to be added by you.

Now, you might think, “Why can’t I use the regular fertilizers I already have?” It’s a fair question but not a good option. 

Regular fertilizers for soil do not contain the nutrient balance your hydroponic plants require.

But do not shake your head in despair; replacing messy soil with clean water will take your indoor gardening to new heights. And even though hydroponic plants have specific needs – it is easier than you think.

Hydroponic basil and Pak Choi
Hydroponic basil and Pak Choi

Hydroponics is where gardening meets science, but you will understand how it all fits together in a few minutes.

And your results will speak for themselves: healthier plants, faster growth, and a tastier harvest.

Why You Need Special Liquid Hydroponic Nutrients

When you grow plants hydroponically, you use water as a growing medium. And when you add nutrients to the water, you create the nutrient solution your plants need to grow and thrive.

But as you no longer use soil, there is no nutrient buffer. You have to add everything the plants need to your growing medium, the water.

Soil will always hold some nutrients, so we say that soil has a nutrient buffer. When you add fertilizers, compost or another feed every spring and fall you amend and improve your soil. You never start form zero.

Regular fertilizers are not an option as they are designed to be added as a booster for soil and do not hold the complete set of macro and micro-nutrients that hydroponic plants demand.

Hydroponic fertilizers are designed to be:

  • water-soluble
  • concentrated
  • complete

They hold the perfect balance of the required nutrients and dissolve entirely in water, making it easy for the plants to absorb the goodness.

And this precision removes the guesswork and helps you avoid nutrient imbalances.

My 3-part hydroponic fertilizer
My 3-part hydroponic fertilizer

Use specialized liquid nutrients for hydroponics if you want optimal growth, health, and yield in your hydroponic garden. This way, your plants get what they need when they need it.

So far, so good.

But to get a fuller picture, you need to know about the different types of nutrients your plants need. Let’s keep learning and look at the distinction between macro and micronutrients. 

Macro vs Micro Nutrients

Plant nutrients can be divided into two categories: macro and micro.

Macronutrients, as the name suggests, are required in larger amounts. These are the heavy hitters of plant growth: nitrogen, phosphorus, and potassium, often called N-P-K.

Macro nutrients are crucial for the basic building blocks of plant life, including processes and functions like photosynthesis, energy transfer, and cell division.

And then we have the micronutrients. You may never have heard about them and be surprised to learn they, too, are vital. And as the name suggests, plants only need the tiniest trace amounts to stay healthy.

Micros include elements like calcium (Ca), magnesium (Mg), boron (B), copper (Cu), iron (Fe), manganese (Mn), molybdenum (Mn), and zinc (Zn).

Macro- and micronutrients printed on one-part hydroponic nutrient bottle
Macro- and micronutrients in a one-part solution

And even if they are only present in microscopic quantities – as in 0,0075% for molybdenum – they are essential in disease resistance and enzyme functions to help your plants stay healthy and resilient.

This balance between macro and micronutrients is key in hydroponics. Too much or too little of anyone can throw off your plants’ growth.

And how could you add 0,0037% of something? It is impossible unless you are a commercial grower in a laboratory setting. This is a significant selling point for ready-to-use hydroponic fertilizers – ease of use. 

Your plants get everything they need in one easy application.

But should you choose a one, two or maybe three-part solution? And which is better?

One, Two And Three Part Hydroponic Fertilizers

Hydroponic fertilizers typically come in one, two, and three-part formulas.

Each offers different levels of control over how you feed your plants.

I recommend you start with a 3-part solution. It is not complicated and there is no reason to compromise.

One-part fertilizers combine all nutrients in one solution. They are easy to use but less flexible.

Your plants have different needs at different stages of the lifecycle. But your one-part solution is the same whether the plant is flowering and fruiting or forming stems and leaves.

Two-part fertilizers divide nutrients into two separate solutions. You have more control, and they are still relatively straightforward to use.

2-part nutrient solution from iDOO
Two-part solution from iDOO

Three-part fertilizers give you more control to adjust nutrient ratios throughout your plants’ life cycle. Here, you can tailor what you give during the plant’s vegetative, flowering, and fruiting stages.

Sure, with more control comes more manual handling, where each component must be measured and given separately.

But trust me, it is still very straightforward.

So Why Are Not All Fertilizers One-Part Solutions?

One-part fertilizers might seem like the ideal, hassle-free option for hydroponic systems.

So why do many growers prefer multi-part hydroponic plant food?

More control is one obvious reason why many growers prefer multi-part solutions. But control is only one part of the puzzle.

Mixing nutrients into one bottle also increases the risk of nutrient precipitation and micronutrient binding. 

I first learned about nutrient precipitation and binding in a webinar hosted by Dr. Lloyd Nackley, a plant physiological ecologist at Oregon State University. [1]

Iceberg seedlings in DWC  garden
Iceberg seedlings in iDOO DWC garden

Simply put, when you mix nutrients, particularly micronutrients, they interact chemically. This reaction can cause certain compounds to bind together and form larger particles that precipitate, meaning that they settle into a solid state and become unavailable to the plant. 

Besides not being accessible to the plants, this binding of some essential nutrients can also disrupt the balance of the nutrient solution and lead to deficiencies and even toxicities.

This is why your should never mix multi-part fertilizers before adding them. Give them at the same time, but add them separately to prevent binding of micronutrients. 

And to make it even more interesting, these interactions can be pretty complex where factors like pH, temperature, and concentration come into play.

To make a long story short, it is hard to make a complete one-part solution.

Two-part and three-part fertilizers avoid this issue by separating interacting elements. Separating the components gives us a more stable, flexible, and plant-available nutrient mix.

And for most of us, this level of control is something we want. We want to have the ability to optimize plant health and yield, especially in a finely-tuned system like hydroponics.

So, multi-part solutions seem like the way to go. Right? But what about buying solid vs. ready mixed plant foods?

Binding and precipitation is also why it is tricky to mix your own organic hydroponic fertilizer.

Comparing solid and liquid plant foods

For me, this comes down to shelf life.

Solid nutrients last longer than ready-mixed fertilizers.

Still, I mainly use ready-mixed liquid fertilizers. Why? Well, I use them before they get old.

To make a long story short, solid fertilizers are concentrated, long-lasting, and economical. Dissolve them in water and add the solution as usual. If you are buying in bulk, you can save money.

Pouring liquid fertilizer into a measuring cup
You only need a measuring cup and a steady hand

The only downside with solid nutrients is that they sometimes do not fully dissolve, making nutrients unavailable to plants. 

Liquid fertilizers are ready to use and easy to apply. They allow for accurate dosing, but you can argue that they are more expensive over time and have a shorter shelf life.

Which leads me to a bit of a pet peeve of mine. Dosage and application.

A Guide To Dosage and Application Instructions

I always give half the recommended dose when I grow herbs and non-flowering and fruiting vegetables. And my yield does not suffer.

As I see it, the manufacturers choose to err on caution when printing their application rate charts.

But it is, of course, safer to follow the manufacturer’s guidelines. And it is important to remember that factors like plant type, growth stage, and environment play a role.

I am, for example, never stingy with nutrients when I grow hydroponic tomatoes or peppers. 

But one thing holds: never give more than the recommended dosage.

Overdosing will harm your plants.

I recommend starting with a lower dose than recommended and adjusting based on your plants’ health. Looking at your plants and learning to understand their needs is key.

Key Takeaways

  • Hydroponic systems require specialized liquid nutrients, different from regular soil fertilizers.
  • Nutrients come in one-, two-, and three-part solutions, offering varying levels of control and level of handling.
  • Not all fertilizers are one-part solutions due to issues like control, nutrient precipitation, and micronutrient binding.
  • Solid and liquid plant foods have distinct advantages and considerations in hydroponics.
  • Proper dosage and application require observation and adjustment rather than strict adherence to general guidelines.

Understanding and managing nutrients are essential to indoor hydroponic gardening. Ready-to-use three-part solutions help you address all your plants’ needs without risking nutrient deficiencies or toxicities.

Related articles: Learn how Electric Conductivity (EC) tells you how much food or nutrients your plants have access to and how pH determines how well they can access that food.

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Mattias Magnusson: Hello, I'm Mattias, a passionate and experienced gardening enthusiast. I am the creator of, your guide to year-round herb and veggie growing. Let's simplify green living, no matter your space or location.