Here’s What Happens if Fertilizer Freezes

If you live in a cold region, you might have accidentally frozen your fertilizer by leaving it outside or in the garage. It’s good to understand what exactly happens to fertilizer if it freezes so that you can decide whether or not you want to use it.

If fertilizer freezes, crystallines form, which can change the structure of the fertilizer. Because of this, there can be a loss of nutrients, making the fertilizer less effective. If it’s cold and moist, many water-soluble and liquid fertilizers will be completely unusable.

The rest of this article will discuss what happens when fertilizer freezes in greater detail. It will also discuss if it’s acceptable to use a frozen fertilizer, how to prevent fertilizer from freezing, and signs that fertilizer has gone bad.

What Happens When Water-Soluble Fertilizer Freezes?

When water-soluble fertilizer freezes, its structure will change. Humidity from freezing temperatures may also cause the fertilizer to activate, making it less effective if you use it later.

Since water-soluble fertilizer begins to work when mixed with water or moisture, humidity is a big issue. Although humidity is generally an issue in hot temperatures, it can sometimes cause problems in freezing temperatures. 

Therefore, you should always try to keep your water-soluble fertilizer away from humidity and extreme temperatures (hot or freezing).

Additionally, extra moisture will be present as the fertilizer eventually begins to thaw. This moisture can also cause issues with water-soluble fertilizers. It’s best to dispose of frozen water-soluble fertilizer because it has likely lost some nutrients.

What Happens When Liquid Fertilizer Freezes?

When liquid fertilizer freezes, some crystallization may occur, and the liquid will expand. Therefore, the fertilizer must have some extra space in its storage container to grow in size. It should be safe to use liquid fertilizer after it’s frozen.

However, you must remember that liquid fertilizers contain different ingredients and chemicals; some may separate when frozen and thawed. If you notice any separation, you should mix the components back together or shake the fertilizer well before applying it to the soil.

Although it should be okay to use a liquid fertilizer that has been frozen, you should avoid keeping it at freezing temperatures. The favorable temperature to store most fertilizers is around 55 degrees Fahrenheit (13 degrees Celsius).

Should You Use a Fertilizer That Was Frozen?

You shouldn’t use a fertilizer that was frozen if it’s water-soluble because the freezing and thawing can create moisture. This moisture will affect the fertilizer and make it less effective when applied to the soil. However, it should be safe to use if it’s a liquid fertilizer. 

Using a fertilizer that was once frozen is entirely up to you. Using a new fertilizer that has never been frozen is best to ensure your soil and plants get all the required nutrients. That way, you don’t have to worry about it not being effective. 

If you decide to use frozen fertilizer, ensure it’s fully thawed before applying it to the soil. You should also make sure you mix all the ingredients thoroughly. As I already mentioned, the freezing and thawing processes can cause specific components to react differently and separate.

Ensuring everything is adequately incorporated will increase the chances of the fertilizer working when applied to the soil.

Thawing Frozen Fertilizer

If your fertilizer has frozen, you might be wondering the best way to thaw it if you’re planning on using it again. The first thing you’ll need to do is remove it from the cold temperatures and place it somewhere warmer.

You can simply leave it there and let it defrost at room temperature. But if you want to use it soon, you can place it in a water bath with warm water. This warmth will allow it to defrost faster, allowing you to use it immediately.

If using the warm water method, keep a close eye on the fertilizer. As soon as it fully thaws, you must remove it from the water to avoid the temperature getting too hot.

If you plan on leaving it at room temperature to defrost, it could take many hours, depending on the amount of product. You might need to leave it overnight if defrosting using this method.

You should ensure that you thoroughly defrost the fertilizer before applying it because it could affect the temperature of the soil. And as you may know, the soil temperature is essential for a plant’s health and growth. 

The plants may stop growing if the soil becomes too cold from the partially defrosted fertilizer. It can permanently affect the plants in the surrounding area, so you must defrost it entirely before use!

Why Is It Bad To Store Fertilizer in Freezing Temperatures?

It is bad to store fertilizer in freezing temperatures because it may affect the structure and nutrients in the fertilizer. As a result, the fertilizer may not work as well as it should when added to the soil.

The most significant change that occurs when fertilizer freezes is crystallization. This process is when your fertilizer turns into a crystal, significantly changing its structure. 

Fertilizer is supposed to remain the way the manufacturer intended it. It’s not supposed to crystallize or change the structure in any way. So, you must always avoid storing it at freezing temperatures.

Some fertilizers may lose some nutrients during the freezing and thawing processes. Although this isn’t always the case, it’s entirely possible.

Safely Storing Fertilizer To Prevent Freezing

Knowing how to store fertilizer safely will eliminate the chances of it freezing. Luckily, storing it is easy once you follow all the proper guidelines. One important thing to remember is that certain fertilizers may have different storage requirements. So before you store yours, make sure you read the storage instructions.

To learn some helpful tips on safely storing fertilizer, check out the sections below:

Check the Instructions

As I just mentioned, you must check the instructions on your fertilizer’s packaging. If you no longer have the packaging, you should assume you need to store it in a cool, dry place away from sunlight.

While most fertilizers can be stored the same way, some might have different needs. That’s why checking the back of the packet before continuing is good.

Store the Fertilizer in a Cool Place

You need to find a cool, dry place to store your fertilizer safely. You won’t have to worry about freezing and crystallizing if you do that. For most, this would be a cupboard that’s out of reach of children and animals. If you have young children, store the fertilizer up high, or lock it away somewhere.

Synthetic fertilizers contain harsh chemicals that can be toxic if consumed, so it’s essential to keep them away from young kids.

Store Fertilizer Indoors

Even if the temperature is right outdoors, you should avoid storing fertilizer there. You can’t control the weather, and it could get freezing overnight without you realizing it. It’s also impossible to control the humidity levels outdoors, and humidity can affect how your fertilizers work.

Keeping your fertilizer stored indoors is always the best course of action!

Disposing of Frozen Fertilizer

You may decide that you want to get rid of your frozen fertilizer if you’re worried it won’t work as well anymore. Since it likely contains harsh chemicals, you must consider the safest disposal option.

The first thing you should do is contact a local waste management service. You can tell the service what you want to get rid of, and the personnel will guide you in the best way. Sometimes, you may need to hire a professional team to get rid of it. You may need to bring it to a particular dump in other cases.

But if you’re out of options, you’ll need to dispose of the fertilizer in your general trash can. When doing it this way, you must keep it in its current packaging. Don’t pour it from the packaging directly into the trash. You may want to consider adding extra trash bags so that leaks are less likely to occur.

However, if the fertilizer is organic (i.e., it doesn’t contain harmful chemicals), you can place it in the trash without worrying about the toxicity. You also won’t have to worry about using extra trash bags or contacting a waste management service.

Signs Your Fertilizer Has Gone Bad After Freezing

There are some signs to look out for if your fertilizer has gone bad after freezing. Some of them include:

  • Change in color. If your fertilizer has changed color after thawing, it’s gone bad. You should avoid using it in this instance.
  • Change in texture. A change in overall texture signifies that your fertilizer has gone bad, and you shouldn’t use it.
  • Separation. Separation can occur after freezing, but you can usually fix it by mixing everything back together. If the fertilizer is separated and you can’t get it back together, it’s likely gone bad.


If fertilizer freezes, it crystallizes and often changes in structure. These changes can sometimes hinder the performance of the fertilizer, so you may need to use a new one.

However, sometimes it’s safe to use fertilizer once it’s thawed. If in doubt, throw it out safely and use a new one.

Alexander Picot

Alexander Picot is the principal creator of, a website dedicated to gardening tips. Inspired by his mother’s love of gardening, Alex has a passion for taking care of plants and turning backyards into feel-good places and loves to share his experience with the rest of the world.

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