What Is The Fertiliser NPK Rating

Q

I've noticed bags of lawn fertiliser have numbers on them, what do these numbers mean, and why are they important to lawn care?

A

The numbers you see on a bag of fertiliser are the N:P:K ratios for that particular brand and lawn fertiliser type. N stands for Nitrogen, P stands for Phosphorous, and K stands for Potassium. These three nutrients are considered to be the most important of the major nutrients for plants, with these major nutrients called Macro Nutrients.

However, Nitrogen, Potassium and Phosphorous are not the only Macro Nutrients needed by plants, other Macro Nutrients include Calcium, Magnesium and Sulphur, but these are often listed as minor elements in Australian lawn fertilisers.

True minor nutrients which are also needed by all plants and lawns are called Micro Nutrients, and are needed in far lesser quantities. The Micro Nutrients include Boron, Chlorine, Copper, Iron, Manganese and Zinc. Micro Nutrients can also be called Trace Elements, and each of the nutrients listed are vital for lawn health.

Most lawn fertilisers being sold today are rather well balanced between most of the nutrients. However, we do not recommend purchasing fertilisers which do not contain any of the Micro Nutrients. Not all Micro Nutrients will be in all fertilisers, and this is not necessarily a bad thing, and has more to do with the total lawn care result the manufacturer is attempting with their own fertiliser blend. Micro Nutrients will not be listed on the front of the fertiliser bag in the N:P:K ratios, but will most often be found listed in another chart on the side of the bag.

Generally when it comes to lawn fertilisers, I like to buy a fertiliser which is manufactured as locally as possible to where I live - because these fertilisers will be best researched and matched to suit our own soil profiles, and I also like to buy a quality fertiliser from a reputable lawn fertiliser company.