Gardening and Plant FAQs

Q: What does NPK mean on Fertiliser Packets?

Fertiliser packetUnderstanding NPK values helps you choose the right fertiliser

NPK represents the key constituent chemical elements Nitrogen (N), Phosphorus (P) and Potassium (K) used in plant fertilisers.

The percentages of these key elements are shown as numbers, e.g. 10-8-12, where the first number is N, the second P and the third K.

The 3 elements promote plant growth in 3 different ways. In simple terms, these are:

  • N - Nitrogen: promotes the growth of leaves and vegetation
  • P - Phosphorous: promotes root growth
  • K - Potassium: promotes flower and fruit growth

When choosing plant fertilisers, the NPK values help you to identify the best fertiliser for the job in hand. For example, lawn fertiliisers are typically higher in Nitrogen to promote leafy growth of the grass.

A balanced fertiliser is when the 3 chemical nutrients NPK are included in equal measures and reflected so in the ratio e.g. 5:5:5. A balanced fertiliser is good for all round, general use.

You may also find Potassium referred to as Potash in many gardening texts.

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FAQ written by . Filed under FAQs: General Plant Care.