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NPK fertilisers – primary nutrients for optimal growth

According to International Fertilizer Development Center (IFDC), about half the global population is alive today because of mineral fertilisers, due to the increased global food supply they provide.

NPK fertilisers are among the most common mineral supplements employed by the agricultural and horticultural industries because of their effectiveness. As a hydroponic grower, you’re likely to have come across NPK liquid fertiliser as well, as it contains all the primary nutrients needed by a plant to grow.

Check out our extensive range of plant nutrients!

What is NPK Fertiliser?

NPK fertiliser takes its name from the chemical symbols for nitrogen (N), phosphorus (P) and potassium (K). These three elements are the primary nutrients needed by all plants to grow and are the main ingredients of NPK fertilisers. Fertilisers also include micronutrients such as molybdenum, zinc and copper which act as water-soluble salts.

Without NPK fertilisers, the available area of productive global agricultural land would be severely diminished, and many more people would suffer in famine conditions. But why are they so critical to plant life? And what do they actually do?


Nitrogen plays several important roles in promoting plant growth. It is a major component of chlorophyll, the compound which uses the sun’s energy to create sugars from water and carbon dioxide during photosynthesis.

Nitrogen is also an essential component of amino acids, the building blocks of proteins. Proteins serve a number of life-critical roles in plants. They form integral structural components of a cell and they act as enzymes, making possible a whole host of chemical reactions upon which the life of the plant depends.

Nitrogen is a component of compounds such as ATP (adenosine triphosphate), which enables cells to store and use the energy released in metabolism. It is also a significant component of nucleic acids such as DNA, the genetic material that allows cells to grow and reproduce.

Signs of Nitrogen Deficiency

The symptoms of nitrogen deficiency in plants include the leaves turning a pale yellow colour or older leaves turning entirely yellow. This is due to a reduction in chlorophyll concentration.

Stunted growth is also a sign of nitrogen deficiency in plants due to a reduction in protein production. The plant cannot make the necessary proteins without a rich supply of nitrogen.


Phosphorous plays key roles in plant structure and as an enzyme to facilitate essential chemical reactions.

Like nitrogen, it plays a significant role in photosynthesis, is a key component of both DNA and RNA, and is a vital component of ATP which plants use for energy storage and release.

Therefore, the element is essential for general growth and vigour of a plant. However, it has been linked to other, more specific activities, including:

  • Stimulated root development
  • Increased stalk and stem strength
  • Improved flower formation and seed production
  • More uniform and earlier crop maturity
  • Increased nitrogen N-fixing capacity of legumes
  • Improvements in crop quality
  • Increased resistance to plant diseases
  • Supports development throughout entire life cycle

Signs of Phosphorous Deficiency

Unlike nitrogen deficiency, plants suffering from a lack of phosphorous often have no symptoms, which can make it difficult to diagnose. Although there might be general stunting early on, by the time recognisable symptoms display, the plant is often past saving.

For this reason, it is essential that phosphorous levels in plants are maintained with a good NPK fertiliser.


Potassium has a large range of functions in a healthy plant, which take in photosynthesis, energy production, water regulation, protein and starch synthesis and as an enzyme.

In photosynthesis, for example, potassium directly controls the opening of stomata – tiny openings on the underside of leaves – which regulate CO2 uptake.

Potassium triggers the activation of enzymes in the creation of ATP and regulates the uptake of water from the roots and its loss through the stomata.

It is also essential in almost every step of protein synthesis, making it central to normal growth and sustaining the plant’s life.

Signs of Potassium Deficiency

The main symptoms of potassium deficiency include a yellowing of the leaves due to a reduced chlorophyll concentration, slow or stunted growth due to a lack of protein being created, poor resistance to temperature change and droughts, and defoliation.

Plant Health in a Hydroponic Environment

Plants grown in a hydroponic environment have the same nutritional requirements as plants grown in other settings, so it is vital that they receive the correct amounts of nitrogen, phosphorous and potassium to thrive.

The only way to be sure of this is to invest in a good quality NPK fertiliser, as this will provide the necessary primary nutrients and trace elements vital for good plant health.

Thankfully, here at Grown Up Hydroponics, we have a wide range of nutritional plant products that you can order online, or pop into the shop and pick up.

Check out our range here or give us a call if you’d like some advice on which products are best for your crop!

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