PlantAdvice.co.uk

For free and impartial advice on general plant care and gardening

28 August 2008

Plant and Gardening FAQs

Category: General Plant Care

Q: What does NPK mean on fertiliser packets?


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

The percentages 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.

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