3 hessian sacks with the letters NPK sign posted.

What is in Fertiliser?

What is in Fertiliser: The Three Main Ingredients


Hello everyone! Rich from Mowd here. This week, we're going to discuss the three main ingredients you'll find in fertilisers. When you look at the label on most fertilisers, you'll see the letters NPK, which refer to the ingredients inside the bag. N stands for nitrogen, P stands for phosphorus, and K stands for potassium. In addition to these letters, you'll also find a number that follows, indicating the percentage of each ingredient. For example, our "Feels Like Summer" fertilizer has an NPK of 12-3-9, meaning it contains 12% nitrogen, 3% phosphorus, and 9% potassium in a 1 kilo bag.

The Importance of the Right Amount of Fertiliser

So, why is it important to put down the right amount of fertiliser on your lawn? Well, different nutrients require different rates of application. For nitrogen, somewhere between 80 and 200 grams per square meter per year is recommended, depending on the type of grass and its usage. By knowing the percentage of nitrogen in your fertilizer, you can schedule and plan how much to apply. The same goes for phosphorus and potassium.

The Role of Nitrogen

The first ingredient we'll discuss is nitrogen. Nitrogen is responsible for promoting the growth of the grass blades. It's commonly found in cheaper fertiliser brands, as it encourages rapid top growth. While this may make your lawn look lush and green, it often fails to support the growth of strong roots or provide disease resistance. The amount of nitrogen needed varies throughout the year. In the winter, less nitrogen is required, while in the spring and summer, more nitrogen is needed to encourage healthy blade growth.

The Importance of Phosphorus

The next ingredient is phosphorus. Phosphorus is essential for root growth. It plays a crucial role in developing deep and wide roots, which allow plants to absorb nutrients from the soil efficiently. A healthy root structure is vital for the overall health and longevity of your lawn. Without enough phosphorus, your grass may struggle to establish strong roots and may be more susceptible to stress and disease.

The Overlooked Nutrient: Potassium

Potassium is often overlooked but is a highly important nutrient for your lawn. It is not found in high quantities in many fertilisers on the market due to its cost. Potassium is responsible for promoting disease resistance, especially during stressful periods such as winter, heavy frosts, waterlogging, and heavy foot traffic. It helps protect your grass from diseases and ensures it remains healthy throughout the year. Our fertilisers at Mowd contain a high level of potassium to keep your lawn in top condition, all year round.

Remembering NPK: Up, Down, and All Around

A simple way to remember the role of each nutrient is to think of NPK as "Up, Down, and All Around." Nitrogen is everything above the ground, supporting blade growth. Phosphorus is everything below the ground, promoting root growth. And potassium is everything around, protecting your lawn from diseases and stresses. By understanding these three main ingredients, you can choose the right fertiliser for your lawn's specific needs.


Thank you for reading today's blog post! We hope you found it informative and useful in understanding the three main ingredients found in fertilisers. Remember, nitrogen is for blade growth, phosphorus is for root growth, and potassium is for disease resistance. By using the right fertilizer and applying the correct amount, you can ensure your lawn remains healthy and vibrant throughout the year.

We've carefully put together our lawn care subscriptions, so you don't have to worry about which fertiliser to buy.  We send you the right fertiliser, at the right time, to your door!  The easiest way to enjoy your garden.

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