Hydroponic Nutrients Guide

Author: Kevin Espiritu, Epic Gardening

This post is designed to give you an overview of hydroponic nutrients – what they’re made of, what they do, and the different types.

What are Hydroponic Nutrients?

Because we are growing plants without soil, we miss out on a good deal of nutrients that soil contains. When mixed with water, hydroponic nutrients are designed to replace all of the macro and micro nutrients found within soil. So, exactly what makes up a bottle of nutrients?

The first thing you’ll notice when you browse through bottles of nutrients are three numbers printed on the front of every bottle. This is known as the N-P-K ratio, or Nitrogen/Phosphorus/Potassium ratio.

The NPK ratio tells you exactly how much of each macronutrient the bottle contains. If a bottle says 9-9-9, this means that the solution contains 9% Nitrogen, 9% Phosphorus, and 9% Potassium. You might have noticed that this adds up to 27% – what’s in the other 73%? Typically, water, micro nutrients and other chelating agents make up the rest of the solution.

The NPK ratio will differ depending on what phase of growth the plant is in – but we’ll get to that later. First, let’s talk about what these different macronutrients do for a plant’s growth.

What Do Plants Need to Grow?

Before we dig into hydroponic nutrients, it’s important to understand exactly what nutrients plants need in the first place. Just like animals, plants need certain elements to survive and thrive.

There are two types of nutrients they need: macronutrients and micronutrients.

By understanding each one of these macro and micro nutrients, you’ll be able to figure out what your specific plant needs as well as any problems that might arise from a deficiency or surplus in any of them.


Nitrogen, Phosphorus, Potassium. These three nutrients are absorbed in the largest quantities by plants and are known as macro nutrients. They serve absolutely vital roles in a plant’s development.

Here’s what each of them do:

Nitrogen (N)

Without nitrogen, plants have no ability to produce leaves. It’s responsible for a lot of the core functions of a plant’s growth:

  • Leaf growth
  • Leaf color
  • Amino acid, proteins, nucleic acid, and chlorophyll synthesis

You can tell your plants have enough nitrogen when their leaves have a vibrant green color and their growth rate isn’t slow.

If your plants are suffering from a nitrogen deficiency, the first place you should look are the older leaves. They typically display the telltale signs of a nitrogen deficiency first: yellowing leaves.

Phosphorus (P)

Phosphorus is essential for proper synthesis of a plant’s DNA and RNA. It’s also necessary for the proper development of many parts of your plants:

  • Stems
  • Roots
  • Flowers
  • Seeds

As you might imagine, your plants will need more phosphorus as they reach their flowering stage, but it’s essential throughout the entire life cycle of your plants.

Phosphorus deficiencies will cause stems to be weak, leaf and root growth to slow down, and flowers and seeds to be either malformed or not develop at all.

Potassium (K)

The main role of potassium in a plant’s life is to synthesize both proteins and carbohydrates. It also plays a role in the development of flowers, roots, and stems to a smaller degree.


Plants need more than the three macronutrients to thrive. The following nine elements are known as micronutrients, and are required in smaller quantities for a healthy plant.

Boron – Combined with Calcium, helps to form cell walls.

Calcium – Combined with Boron, helps to form cell walls.

Copper – Activates enzymes and is required for respiration and photosynthesis.

Iron – Used to form chlorophyll and in respiration of sugars for energy.

Magnesium – Catalyzes the growth process and makes oxygen during photosynthesis.

Sulfur – Synthesizes protein, helps with fruiting, seeding and water uptake. Also acts as an organic fungicide.

Zinc – Helps to form chlorophyll, along with assisting respiration and nitrogen metabolism.

Types of Hydroponic Nutrients

Nutrients typically come in two different varieties – powdered and liquid.

The powdered variety is generally harder to work with. It won’t dissolve fully into water and oftentimes doesn’t have added pH buffers.

Liquid varieties are much more popular and easy to use. They come highly concentrated, so it’s important not to spill any on your body or your plants. Other than that, they’re fairly easy to use. All you need to do is mix them thoroughly into water at the desired concentration, and you’re set. Most of them come with pH buffers, which means that you don’t have to balance the pH of your water yourself – the nutrients do it for you.