Skip to Content

Using Cat Food as Plant Fertilizer: What You Should Know

Spread the Word!

Cat food as fertilizer may seem unorthodox but making use of leftover or expired Cat food from your Cat feeder may be a good alternative to using normal fertilizer for plants since it also contains nutrients.

Cat food contains an array of nutrients and proteins. These nutrients can also be useful to plants as a fertilizer. Cat food doesn?t directly provide nutrients to the plants, but by secondary action whereby bacteria firstly breaks down the food into nutrients which is made available for plants to use.

But how would plants use this protein? Would it smell? And would it attract any unwanted guests to your plants? This article will explore whether it is good to use cat food as plant fertilizer as well as its benefits to the plant when broken down by bacteria in the soil.

Using Expired Cat food as fertilizer

Using cat food as plant fertilizer

When Cat food passes the expiry date, it doesn?t mean that the food is not good again. The expired date is a marker showing that it is not recommended for its primary use after the marked date has passed.

Cat food contains proteins, fibers, fats, vitamins along with a number of other additives and preservatives meant for the food not to smell and have a long shelf life. This is crucial since we?re dealing with an unrefrigerated protein product.

If you want a slow-release fertilizer that will ensure your plant grows healthy for a long time with minimal intervention, I recommend Osmocote Smart-Release Plant Food.

Osmocoat fertilizer

How do these Ingredients in Cat Food Help Plants?

Adding cat food to the soil will have no direct benefit to the plant.

However, once incorporated properly with the soil, bacteria and microbes will have a field day breaking down and processing the proteins contained in the food.

Protein compound


These are organic compounds made primarily of nitrogen and hydrogen with some carbon and oxygen. 

The proteins are broken down by microorganisms in the soil to produce carbon dioxide (CO2), energy, water, plant nutrients, and resynthesized organic carbon compounds such as Nitrogen.

Microorganisms play a vital role in keeping the soil in a healthy state for plants to grow.

Soil life plays a major role in many natural processes that determine nutrient and water availability for agricultural productivity. The primary activities of all living organisms are growing and reproducing. By-products from growing roots and plant residues feed soil organisms. Source.

Nitrogen’s primary role in plant development is to help produce healthy green flourishing leaves since it is a major component of chlorophyll.

Chlorophyll is a pigment that gives plants their green color, and it helps plants create their own food through photosynthesis.

The cat food would therefore help add an essential source of nitrogen to the soil for plants to grow.

Would the Cat Food Smell?

The smell is a factor to consider when using Cat food as a fertilizer for plants.?

In order for the cat food not to give off that fresh odor it is known for, you will have to incorporate the food into the first 2 to 4 inches of the soil and in some cases bury the food further under the soil to prevent the smell from creating a noticeable distraction in your home.

Apart from the fresh odor, the breakdown of the proteins will also release some smelly gases such as H2S (hydrogen sulfide gas), which is a typical byproduct of protein synthesis.

For these reasons it is recommended that cat food be applied to plants grown outdoors and in the garden.

Using Cat food on indoor plants may not be such a good idea since the smell will get unbearable, fast!

However, what we do suggest if you want to use the food for indoor plants, you can add it to compost and allow it to be fully decomposed first before using it indoors.

Cat sleeping in potted plants

Will the Cat Food Attract Unwanted Animals?

Due to the protein content and other additives, the cat food will attract ants and other animals such as dogs and cats.

This may not be such a good thing since the cats will dig directly into the soil, uprooting the plants and while trying to get to that buried food, or at least what he thought would have been food.

 The result would be two things –

  1. The plants will get damaged 
  2. The cats or dog would get poisoned from eating the potted soil mixture.

It is best to discourage cats from eating potting soil. Potting soil is specially formulated soil that contains ingredients made for plants with specific needs when grown in pots or containers.

The constituents of potting soil are dangerous to cats and cause a variety of ailments when ingested. 

Therefore, try to avoid areas where using Cat food as a plant fertilizer is in close proximity to pets and other wild animals.

Cat Food Vs Plant Fertilizer

Cat Food and Plant Fertilizers are created from totally different byproducts as they are intended to feed two different species.

Plant fertilizers offer a source of burn-free nitrogen, along with the other primary nutrients. 

Cat food and Plant fertilizers differ from each other as the plant fertilizer directly feeds the plant while the cat food has to firstly be broken down before the nutrients are available for the plant.

What this does is create a slow release of beneficial nutrients for the plants rather than shocking it with nutrient-rich doses, as with regular fertilizers, which poses the risk of burning the plant. (Fertilizer burn)

How to Apply the Cat Food to the Soil

This is probably the most important part of this article, its application!

Applying Cat food to the soil the right way is important in preventing unwanted animals from eating the soil and digging up the plants.

The Cat food should be mixed in 2 to 4 inches with topsoil first before adding it to your plant pots or garden plants.

This helps lower the odors presented by the Cat food and also helps the bacteria to access the food sooner.

After addition, the soil should be watered lightly and allowed to rest.

The water would cause the cat food to expand and break down faster. 

Another method is to add water to the cat food which would cause it to expand and break up before mixing it into the soil. 

This would also increase the rate at which the bacteria break down the food into beneficial nitrogen for the plants.

Covering the Soil to Prevent Smells and Unwanted Attention

Having any type of pet food in the soil can attract unwanted attention which can unearth the decaying food and bring up some questionable smell with it.

Covering the top layer of the soil by mulching can help prevent this occurrence as it creates a barrier for curious pets.

In this case, stones can be used and apart from the beauty it will add to the plant its weight will deter other animals from moving it aside to access the pet food beneath the soil.

However, be careful not to use too much stone as much as it can cause the soil to become compressed after time which can lead to watering problems.

 The Takeaway 

Cat food is a good alternative to regular fertilizer since it adds a slow release of beneficial nitrogen and other nutrients for plants to grow.

Some consideration for pets and other wild animals should be taken when adding the fertilizer to the soil and it should be done in areas away from pets.

Adding cat food to the soil should be done such that the food is broken up and totally mixed in with a soil mixture before it is added to your plants to help the breakdown of the food and lower the potential smell that comes with the cat food.

Spread the Word!

Free Plant Care & Gardening Guides