Ever wondered what does NPK stand for on fertilizer bags? At a glance, these numbers can seem so confusing.

I Have received quite a few requests for an article explaining those confusing numbers on fertiliser bags, so many people want to know what does the NPK stand for on fertilizer bags.

.Let’s start by looking at the 8:1:5 from Culterra as an example. 8:1:5 (22) N:P:K

At first, these numbers can look like Greek, but once we know what they stand for it makes more sense. We call these numbers the N:P:K ratio and this shows the ratio of the different elements with each other. LET’S talk a bit more about these elements.

What does the N of NPK stand for on fertilizer bags?

N = Nitrogen: Nitrogen plays a key role in a plant’s colouring and chlorophyll production, making it an important factor in leaf development. Fertilizers high in nitrogen are mainly used for lawns and plants that are used for their foliage or if YOU require lots of growth. Yellowing of leaves especially on the new growth is a sign of nitrogen deficiency. Applying a fertilizer high in nitrogen will fix the problem. Nitrogen can burn the plants roots so it is very important to just apply the right amount and water thoroughly afterwards.

What does the P of NPK stand for on fertilizer bags? 

 P = Phosphate Phosphate plays an important role in the development of roots. Phosphate is used primarily as Bonemeal or Superphosphate. Phosphate is a very stationary element, which means that it doesn’t move through the soil as easily as other elements. This is the reason why we add it to hole before we plant, ensuring that it is close to the roots. Bear in mind that if you have dogs rather use superphosphate as they are prone dig after the smell of bonemeal.


What does the K of NPK stand for on fertilizer bags

Potassium: Also known as Kalium, Potassium is the main element that assists in flowering and fruiting. It also contributes to the overall health and vigour of plants and helps to strengthen the PLANT’S ability to protect itself against diseases.


 Now that we know what NPK stands for on fertilizer bags it is a lot easier to know what these numbers do. If you want growth and a foliage boost, use a fertiliser high in Nitrogen. If you want more flowers or FRUIT, use a fertiliser high in Potassium. I hope this helps in explaining an OFTEN-CONFUSING TOPIC.

More resources

Fertilizers Explained – Macronutrients, Micronutrients and Slow-release Fertilizers