Can You Vermicompost Cat Litter?

Vermicomposting is a great way to reuse and recycle food and other waste products that otherwise would end up in landfills. Pet owners know that cats can produce lots of waste, often thrown away in plastic bags destined for the dump. They generate a massive amount of waste, making cat parents wonder if vermicomposting can be a solution for repurposing cat litter.

You can vermicompost some cat litter. The ability to vermicompost cat litter is determined by the type of litter and the health condition of your cat. However, you should not use fertilizer made from cat litter to grow food.

If you are thinking about adding cat litter to your vermicompost system, it is doable, but there are a few things you need to consider before you begin. This article will tell you everything you need to know to be successful.

Factors to Consider When Vermicomposting Cat Litter

To vermicompost cat litter, you can add it to the bin with worms, just like any other waste. However, it is essential to give the litter time for the ammonia to evaporate before adding it to your worm bin because the excessive amount of the substance might kill the worms.

With a few additional considerations, vermicomposting cat litter follows the same basic steps as kitchen waste.

Here are some factors to consider when vermicomposting cat litter:

Concentrations of Ammonia and Salt

One of the biggest concerns about composting cat litter is the levels of ammonia and salt. Cat urine contains ammonia and inorganic salt, which can kill redworms quite quickly.

To work around this, there are three good options:

Add Carbon to the Litter

Carbon helps to quickly neutralize the ammonia and salt in the litter that will otherwise kill the worms. Adding things like leaves, peat moss, and sawdust will help absorb the nitrogen released from the litter. 

Let the Cat Litter Sit for a While Before Introducing Worms

To lower ammonia levels in cat litter, you have to allow it time to evaporate. Add some water to the litter to absorb some of the ammonia and help it evaporate faster. Make sure the water evaporates, so the bin does not grow mold. There is no studied time frame for ammonia evaporation, but after a few weeks, you can add a few worms to the pile and observe their reaction. 

Create Two Vermicomposting Bins Next to One Another

Having two bins is a good system because it lets the worms decide when to enter the bin. Worms can move back and forth between bins that are nearby. Creating a bin without cat litter next to the cat litter bin allows the worms to stay in the safe bin until the ammonia levels die down. The worms can then migrate between the bins themselves.

Uses for Fertilizer

A vermicompost bin does not get hot enough to kill germs and parasites that may be in the cat waste. Therefore, it is vital that you do not use the resulting fertilizer to grow food. 

For that same reason, you cannot keep a vermicompost bin with cat litter within 20 ft (6 m) of a bin that you will use for food fertilizer. If you create two neighboring bins, as discussed above, they both need to be considered unsafe for food, even if one only contains cat litter waste.

Health Considerations

Animal waste, such as cow dung and cat feces, contains many germs and parasites that require extra caution. The germs and parasites present in these waste products can cause serious health problems. You should never handle cat litter without gloves or touch your eyes, nose, or mouth before washing your hands thoroughly.

It is highly recommended that people who are immunocompromised do not consume animal waste of any sort. 

Litter Types That Can Be Vermicomposted

Cat litter that is natural and chemical-free can be vermicomposted. Litters labeled as compostable are fine for vermicomposting, but biodegradable litters need to be assessed individually. 

Each year, 10 billion pounds (4.5B kg) of cat waste ends up in a landfill, not even counting the litter. It would be great if they could all be vermicomposted. However, not all types of litter are compostable, so it is essential to look into the acceptable types of litter before you begin vermicomposting.  

Biodegradable vs. Compostable

With the increasing demand for eco-friendly products, many companies will advertise their cat litter as biodegradable or compostable. But you have to be careful because these terms are not interchangeable.


Compostable cat litter is made from plant products. Litter can be made out of natural materials, such as pine, corn, and walnut shells. Compostable cat litter should not have any harmful chemicals, making it fine to vermicompost.

Like compostable litter, cat litter may also be labeled as “all-natural”, which is also fine to vermicompost.


On the other hand, the biodegradable label on some cat litter does not mean much. For an ingredient to be considered biodegradable, it needs to eventually decompose into its respective parts. By this definition, fabric, aluminum, and even styrofoam are scientifically considered biodegradable. 

This is not to say that cat litter labeled as biodegradable is never compostable, but you cannot assume that it is. Take a careful look at the ingredients in a litter, being especially aware of any chemicals it may contain.

Compostable and Non-Compostable Litter Components

Let’s look at the most common kinds of cat litter and whether they are acceptable for vermicomposting.

You can vermicompost cat litter that contains:

  • Pine
  • Wheat
  • Grass
  • Corn
  • Walnut shell
  • Newspaper

Pine, wheat, and walnut shells are perfect litter materials because of their high carbon content, which provides extra neutralization of the chemicals in cat urine.

You cannot vermicompost cat litter that contains clay or silica gel.

How Cat Health Affects the Litter Vermicompost

Litter from cats with acidic urine or abnormalities in their stool cannot be vermicomposted. Cats should be tested for infections before beginning a vermicompost system with their litter. 

You should test the pH of your cat’s urine before beginning the vermicomposting and every so often moving forward. If the pH level is greater than 7, it is too high and indicates a health problem. 

Not only does this result in a higher concentration of ammonia, but it can indicate deeper health problems that can make the cat waste more unsafe to handle. You can test the pH of a cat’s urine with an at-home kit or at the veterinarian’s office.

You cannot use the litter of cats with parasites or intestinal worms in their stool for a vermicompost bin. Vermicompost piles do not get nearly as hot as traditional compost piles, so they cannot kill off parasites and worms at the same level. These parasites will also kill off the worms in your bin. 

Parasites can only be found under the microscopic examination of stool samples, so you will need to ask a veterinarian to run a test for you. This test should also be a part of an annual wellness exam for cats.

Vermicomposting Duration: 3-6 Months

Cat litter takes an average of 3 to 6 months to vermicompost. The amount of time it will take for your bin to become usable fertilizer depends on the amount of litter you add to it and the number of worms in the bin.

Vermicomposting is much faster than ordinary composting. The decomposition process with worms typically generates heat, speeding up the breakdown of cat litter. The speed of decomposition of cat litter also increases with an increase in the number of worms.

In a compost pile without worms, it would take roughly 12 months for cat litter to decompose. 


Cat litter can be vermicomposted and used as fertilizer for non-food plants, but you need to neutralize the ammonia and salt in cat urine before adding them to a worm bin. You can give it time to evaporate or introduce a second bin for the worms to stay in until they are ready.

Compostable cat litter can be vermicomposted, and you can also use some biodegradable litter that doesn’t contain chemicals.

It is also best to test your cat for parasites, intestinal worms, and urine acidity before adding their litter to your bin.

Discover how long your new batch of vermicompost will last in my article How Long Does Vermicompost Last?

Dr. Moritz Picot

Dr. Moritz Picot is a horticulture enthusiast and the founder of, where he serves as the lead content writer. He established the website in 2022 as a valuable resource for both gardening aficionados and beginners, compiling all the gardening tips he has accumulated over the past 25 years. Alex has a passion for nurturing plants, transforming backyards into inviting spaces, and sharing his knowledge with the world.

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