What is Fertilizer Made of – Everything You Need to Know

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You’re supposed to add fertilizer to your garden to make your plants and vegetables grow better. But what exactly is fertilizer and do you have to buy it or can you make your own?

What is fertilizer made of: The easy way to understand what fertilizer is made of is to think of it as food. You are feeding your plants the important nutrients you need, and thus you should do so on a regular basis. Organic fertilizer can come from compost and manure and is a great addition to your garden during the spring and fall. Inorganic fertilizer contains nitrogen, phosphorus, and potassium, and you can purchase different ratios of these compounds, depending on what type of crops you have. Make sure your fertilizer can penetrate deep into the ground and always give a thorough watering after you use inorganic fertilizer to help it reach the root system of your plants.

Organic vs Inorganic Fertilizer

When we talk about fertilizer, there are two main types, organic and inorganic. Both are useful in your garden and which one you choose will ultimately come down to the availability of a certain fertilizer as well as your garden’s needs.

Organic fertilizer comes in the form of organic matter, such as compost, manure, or bone meal. These substances all contain important nutrients that slowly break down and are absorbed into the soil.

If you have access to these substances, you should regularly add them to your garden. Aim to build them into the soil in the spring and the fall.

Those that don’t have a compost bin or access to organic fertilizer can instead opt for an inorganic compound. These are readily available online or at your local gardening shop.

The benefit of inorganic fertilizers is that they are specially formulated to have different ratios of chemicals. It is a more exact way of putting what you need into your garden.

What are the main ingredients in fertilizer?

If you purchase an inorganic fertilizer, it will almost always have three numbers on it. This will be a ratio of what is inside.

The three numbers are always in the same order and they refer to nitrogen, phosphorus, and potassium. These are the three essential ingredients that all gardens need.

When you decide which fertilizer to purchase, you should match the quantities of each substance with your garden’s needs. For example, leafy green vegetables need a higher amount of nitrogen than they do potassium or phosphorus.


Perhaps the most important nutrient to add to your garden is nitrogen. All plants need some level of nitrogen in order to grow and develop.

Plants use nitrogen in order to form protein, and protein can be found in the tissue of anything that is living. Without nitrogen, your plants will wither and won’t be able to produce any crops.


Plants grow through a system of photosynthesis in which they convert sunlight into energy. In order to fully complete this cycle, they need to have enough phosphorus to aid in continuous growth.


Gardeners who want their plants to be able to withstand the onslaught of disease will do well to ensure there is a good quantity of potassium in their fertilizer. Potassium also helps to increase the overall yield of your crops.

Other Ingredients

The three numbers on an inorganic fertilizer refer to the percentage of potassium, phosphorus, and nitrogen. So, if you have a 10-15-10, it means 10% nitrogen, 15% phosphorus, and 10% potassium. But what about the rest of the ingredients?

Trace elements

While your soil doesn’t need a lot of trace elements, it still needs small amounts. This can include minerals such as magnesium, zinc, copper, and manganese.


Because fertilizer is a mixture of chemicals, a bag will also hold some filler ingredients. These are responsible for keeping the mixture from drying out or clumping.

Time-release ingredients

When you add fertilizer to your garden, you want it to last a little while. Some fertilizer products will include time-release ingredients so that they will slowly release into the ground and not all at once.

How does fertilizer work?

With plants, the roots do a lot of the heavy lifting. While underground, roots will grow out and absorb water and nutrients from the soil.

When you add fertilizer to your garden, you are essentially adding nutrients to the soil so that the roots of your plants can find it and absorb it.

If you plan on using inorganic fertilizer, such as a powder, you want to ensure it is fully saturated into the soil. If it remains on top, then the roots of your plant can’t get to it.

With a powder fertilizer, you can choose to mix it with a container of water to dilute it. Another option is to sprinkle it on top of the soil and then give the area a really good watering so that the fertilizer goes into the soil.

Why do plants need fertilizer?

Within the soil is a finite amount of nutrients. And once these nutrients are gone, your plants essentially don’t have any food left to nourish them.

Adding fertilizer is like adding food to your plants. It gives them what they need so they can remain healthy and grow.

Some plants, especially vegetables, only grow for a part of the year. Once these plants are done growing, you should dig up the garden and add organic fertilizer to replenish your soil.

Other plants, known as perennials, will live in the same soil area and thus it is harder to dig around them as you don’t want to disturb the roots. While you can still add organic matter around the soil, adding a powdered inorganic fertilizer is an easier way to give new life to the soil.


Keeping your garden healthy involves a regular supply of fertilizer. You can choose to use an organic substance, such as compost or manure. You can also choose to use an inorganic substance with is specially formulated to contain nitrogen, phosphorus, and potassium, as well as smaller amounts of other minerals.

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