What Is NPK Fertiliser And Should You Use It?

Last Updated on June 29, 2022 by Real Men Sow

For healthy growth, plants require a variety of nutrients. These nutrients are in the soil naturally, but you can add more through fertilizers to increase growth rates, performance, or crop yields. This is when an NPK fertiliser comes in handy.

What Does NPK Mean?

Three of the most important nutrients for plants are potassium, phosphorus and nitrogen. NPK is the initials of their chemical name.

What is NPK fertilizer?

Fertilizers are plants’ food that comes in a concentrated form, such as powder, granules or liquid. There are many terms to describe fertilizers that contain NPK, the major nutrients. These terms include Universal, All-purpose, Complete, Compound and Complete. There are many brands and types to choose from when it comes to all-round fertilizers. These are ‘general’ fertilizers. However, there are fertilizers that can be used for specific plants like tomatoes or roses.

What Do The Letters in NPK Fertilizer Mean?

The product labels contain a breakdown of the major nutrients N and P, as well as their percentages. This is what you can call a balanced fertilizer. If one number is greater than the others, it means that the fertilizer’s proportion is different and is best used during a specific time of the year. Understanding the purpose of each fertilizer is helpful as plants require different amounts of nutrients at different times of the year.

Nitrogen, the N in NPK

Leafy growth is stimulated by nitrogen (N), which is needed most in the spring and early summer. Applying a high-nitrogen fertilizer too late in the season can cause soft leafy growth to be damaged by frost. Lawn food is a high-nitrogen feeder.

Phosphorus, the P in NPK

Because phosphorus (P) promotes root growth, higher levels of phosphorus should be used when planting, especially in autumn. Bone Meal has high levels of phosphorus.

Potassium, the K in NPK

Potassium (K), which aids in the formation of flowers and fruits, should be applied from the late spring through the end of summer. A tomato feed, which contains high levels of potassium, is an example of such a feed. It is used to increase the production of fruiting plants (especially tomatoes) and flower blooms.

Choosing Fertilizers

Consider what fertilizer you will use it for. If you are looking to produce a large crop of tomatoes, aubergines, or chillies, you will need a high potassium (K), feed like a tomato feed. To aid root growth, add bonemeal (which has high levels P) to your planting hole if you are planting. You can also think about ease of application. Granular fertilizers or powdered fertilizers are quick and easy to apply. Usually, you only need one or two applications per growing season. Concentrated fertilizers require diluting and watering, and application are more likely to be frequent.

How fast nutrient is distributed

Also, think about the effect you are looking for and how fast you want the fertilizer release to be to your plants. Pellet fertilizers release nutrients slowly while liquid fertilizers can act instantly. You should also consider whether you prefer organic or inorganic fertilizers. You can either use natural or artificial fertilizers (inorganic, synthetic), or you can use organic products (organic).

Organic vs Inorganic fertiliser

Inorganic fertilizers are a quick way to feed plants, but they don’t provide long-term benefits for the soil. Organic fertilizers are not only good for the plant, but also feed the soil. This contributes to the soil’s long-term health and supports long-term plant growth.

Do Plants Actually Need Fertilizer?

Healthy soil can provide all the nutrients that plants require. This is especially visible on soil with organic matter amendment, such as, compost or manure. However, hardworking plants such as vegetables and flowering roses may benefit from an extra boost in summer, especially those growing in pots and sandy soils.


It is crucial to find the right balance, as too much fertilizer could be just as harmful as too little. You should also consider the possibility of harm to the environment, as excess synthetic nutrients can pollute water or cause damage to soil life. Remember that plants only absorb nutrients when the soil is moist. Dry conditions can cause plants to show signs of deficiency, even though they are just looking for moisture.

What You Need To Know On Buying NPK Fertilizers

  • You can buy fertilizers at many retailers as well as online.
  • Consider the fertilizer that you require and whether slow-release or instant feeding is best for your plant.
  • You can choose from a variety of organic and synthetic fertilizer
Real Men Sow
Real Men Sow

Hello, I’m Pete and I’m currently based in the west of Scotland, in a small place called Rosneath, where I’m exploring my garden adventures. I personally started gardening around 6 years ago and initially, I started out by growing my favorite fruits and berries, such as strawberries, Raspberries & Gooseberries. Since then I’ve added a lot of vegetables and working closely with my neighbor, it’s been a lot of fun.