Understanding NPK fertiliser Plants require a range of nutrients for healthy growth. These nutrients occur naturally in the soil and can also be added in the form of fertilisers, to boost growth rates, performance, and crop yields. What does NPK mean?  The three major nutrients that plants need are nitrogen, phosphorus, and potassium. These are referred to by the initials of their chemical symbols: N (Nitrogen), P (Phosphorus), and K (Potassium). What is NPK fertiliser? Fertilisers are food for plants that can be bought in concentrated and compact form such as pellets, granules, powder, or liquid. Fertilisers that ...