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How to Read Fertilizer Numbers

The Perfect Guide on How to Read Fertilizer Numbers

Your plants need nutrients, and sure you take care of that requirement with getting fertilizers. But do you know the correct method of reading fertilizer numbers? Get to know the apt and easy way to understand the significance of the numbers, in the article below.
Gardenerdy Staff
Last Updated: May 12, 2018
I must say, for all the plant lovers, maintaining perfect soil conditions is of utmost importance, for the nourishment and growth of plants. And undoubtedly along with water the soil needs another supplement, that is fertilizers. A fertilizer gives the soil essential nutrients that enrich the value and add to the well and flourishing growth of the plant. Today most of the commercial planting, makes use of fertilizers and this has been popular for years. Getting a bag of fertilizers is easy, but most of us find it tough to understand the content that is inside it. Sure there is a numeric code like print on the bag, which denominates the fertilizer that is inside. But it is tough to understand the complete content of the fertilizer, just with a code of numbers. For a layman it's tough to get the whole thing. Like, getting the correct reading of the numbers in the first go, without really understanding the format, the meaning of the numbers and what exactly do they stand for. So to help you out a little, this article is a small effort, just like a tutorial, on how to read fertilizer numbers.

How to Understand Fertilizer Numbers
It may sound like serious math, but it actually is like a puzzle, once you get a link, the rest is easily solved. And to begin with, we will first start with the basics. When you see a fertilizer bag, there will be three numbers printed on it. Now these are the numbers of the content and composition of ingredients in the fertilizer, that are required to be printed, as per the rules of law. These numbers are basically the compounds are the major ingredients of the fertilizers. The 3 compounds that are used are: Nitrogen (N), Potassium (K) and Phosphorus (P). Usually, you will find only three numbers on the bag, however if there appears to be a fourth addition at times, it denominates the compound Sulfur (S). The typical format of the numbers will be Nitrogen-Phosphorous-Potassium, that is N-P-K.

They will appear on the bag in a set like: 21-0-0 or 30-10-10. The first number stands for nitrogen (N), that is, the amount of nitrogen in the fertilizer. The second represents the amount of phosphorous (P) in the fertilizer, whereas the third number represents the potassium content. The numbers will be the units standing for percentage of that compound in the fertilizer. For example, if the number on the bag is, 30-10-10, then we would read it as:

30% nitrogen (N), 10% phosphorous (P) and 10% potassium (K)

Now that we know about reading fertilizer numbers, let's get to understanding the importance of each, in the following.
    • Nitrogen is the first component and is important for the plants to produce chlorophyll. It helps in the production of food, that further help in the growth of plants. It gives the plants the green color they possess. So if the fertilizer is high in nitrogen, it will help your plant grow, and yes, with a healthy green color for the plant.

    • Next comes phosphorous. This compound stands for the overall development of the roots, blooming and budding of the flowers and fruits of the plant. The strength of the roots will help in proper absorption of essentials from the soil. It also helps the plant store the energy. This will eventually give you a stronger and healthier plant with abundant blossom. So the phosphorous content is important for the above mentioned benefits to the plant.

  • With the last one being potassium, this too strengthens the roots. This also enhances, what we call the 'immunity of the plant', which helps the plant in bad weather conditions and keeps it free from any disease. So for maintaining healthy plants even in extreme weather, give them a good dose of potassium through the fertilizer.
When choosing a fertilizer, pay attention to the content of compounds in it. The most important is to understand the requirements of your plants. Get help, and study a little about the types of plants that you are growing. Understanding the needs and the properties of the plant will also help in choosing the apt combination of compounds, that make the fertilizer. Also selecting the fertilizer according to the season is important, if it is summer, you do not want your plants to dry away due to poor nutrition from the soil, so get a fertilizer that is rich in potassium or phosphorous. Choose wisely, and another important aspect is that, understand all the other contents that make the fertilizer too.

So the next time you drop in to carry a bag of nutrition for your soil, you know this little trick on how to read fertilizer numbers, it surely can get you a little 'geeky' pride there!