Can You Use Cat Litter in Hydroponic? Is it Safe?

Clay cat litter has excellent absorption properties which absorb the strong smell of cat urine and excrement. Its absorption properties have found application as a growing medium but is it really worth using or is this just a case of far-fetched experiment?

Clay cat litter is safe and usable for hydroponics as it is nothing more than absorbent clay and thus safe. However, only the baked, non-clumping, calcium bentonite cat litter can be used for hydroponics. Even then, it is not recommended as conventional hydroponic growing mediums are better. Used cat litter should never be used in hydroponic.

There are different types of clay cat litter and only one type can be used. Used cat litter can also pose some risks so read below to be informed.

Can Clay Cat Litter Be Used in Hydroponics?

Clay cat litter is safe and can be used in hydroponics. However, the only type of clay cat litter that is viable in hydroponics is the baked, calcium bentonite, non-clumping variety.

Cat litter is safe because it is nothing more than absorbent clay. Its use in hydroponics is not as prevalent. Even though almost anything can be used as a growing medium in hydroponics, there is a certain mixture of water retention and drainage properties that is generally desired. Clay is unfortunately too absorbent to be useful for hydroponics.

There are other growing mediums which do a better job which will be explained later on.

The 2 Types of Clay Cat Litter

There are two types of cat litter. For the purposes of determining their efficacy, it is important to discuss their similarities and differences.

1 – Non-clumping, Calcium Bentonite Cat Litter

The non-clumping variety’s main ingredient is calcium bentonite and is capable of absorbing its own weight in fluid.

Baked, calcium bentonite, non-clumping is the only viable cat litter because this is the only form by which cat litter would retain its shape.

Cat litter, because it’s made out of absorbent clay, will turn into mush when it comes into contact with excess amounts of moisture. This is why it’s important that it’s “baked.” Baking the clay tempers the cat litter to keep its shape and absorb less water, consequently preventing it from turning into mush.

Cat Litter In Hydroponics – Infographic

2 – Clumping, Sodium Bentonite Cat Litter

The clumping, sodium bentonite cat litter is not recommended as a growing medium in hydroponics because it is too absorbent, more so than the non-clumping, calcium bentonite cat litter.

The clumping variety’s main ingredient is sodium bentonite which effectively causes the litter to “clump” together when it comes into contact with moisture.

Why is Cat Litter Even Used as a Growing Medium?

Despite being a product specifically made for cats, its inherent properties allows its uses to extend far beyond its original purpose.


Cat litter is made of absorbent clay which has a remarkable ability to absorb feces, urine, and the smell coming therefrom. The absorption properties of the cat litter depends on whether it’s the clumping or non-clumping variety.

Sodium bentonite is more absorbent than its calcium bentonite counterpart. The former can absorb 15-20 times its weight whereas the latter can only absorb equivalent to its weight.


For growers who already have cat litter for their house cats, using cat litter may seem like “hitting two birds with one stone” scenario. Depending on your location and market conditions, cat litter may be significantly cheaper than conventional growing mediums.

A grower can effectively save on expenses by only buying cat litter instead of cat litter and growing medium separately. Though unconventional, it is by no means illogical. Given that the results of growers vary, there is nothing lost in experimenting.

Can Used Cat Litter be Utilized in Hydroponics?

Used cat litter (those already with feces and urine) cannot be used in hydroponics or soil cultivation due to the risk of disease transmission. It cannot be used as a growing medium or as organic fertilizer.

First and foremost, cats carry a host of gastrointestinal parasites and a disease which can be contracted from their excrements known as Toxoplasmosis. Exposure could result in body aches, headaches, and fever, among others.

Hence, it is not recommended to incorporate anything involving cat excrements with plants, especially those meant for consumption. Growers with weak immune systems beware!

Historical Use of Clay Cat Litter as Growing Medium

Cat litter first came in the form of absorbent clay which is also the most common available in the market. Its absorbent properties negated the sights and smells of cat urine and excrement.

Clay cat litter can be used as a hydroponic growing medium but they are rarely used. Cat litter is a last resort if, somehow, there are no other growing mediums available.

Historically, in the late 2000s and early 2010s, ponding sites have contemplated the use of non-odorous, non-clumping cat litter as growing medium in slotted pots. Results of its efficacy have been inconsistent. Reports range from good, negative, to no significant difference compared to regular growing medium.

In soil cultivation, cat litter can be used as a growing medium and used as a secondary component to be mixed in with other growing mediums to enhance its absorbent properties.

Conventional Growing Mediums

In light of these facts, clay cat litter seems to be less of an attractive choice as a growing medium. Only a specific type of clay cat litter can be used and even then results are inconclusive whether or not they are as good or better.

Simply put, it is less of a hassle to use a conventional growing medium for hydroponics because they have been tried and tested by growers. They also have the desired balance of water retention and aeration required in hydroponics.

The most popular growing mediums in hydroponics are rockwool, hydroton, and coco coir. Other mediums such as gravel, sand, perlite, vermiculite, gardening soil, and even potting soil.

We have extensively discussed the pros and cons of the most common growing mediums such as coco coir, potting soil, and sand. Knowledge on these mediums are not only useful for hydroponics but also conventional soil cultivation.

Silica Gel Cat Litter

Unlike clay cat litter, silica gel cat litter can be experimentally used as a growing medium in hydroponics. Silica gel cat litter retains its shape and has good absorption properties (even better than perlite).

Silica gel cat litter is a relatively new innovation. It is the porous, granular form of silicon dioxide. It functions similar to perlite but is more water absorbent, heavier, and better aeration. This gives it the desired properties required in hydroponic growing mediums.

Its more water absorbent properties allows it to retain water twice as long as perlite. It also means it can be heavier due to retaining more water.

Its heavier weight due to being naturally heavier and more absorbent means it does better in bearing the weight of the plant and propping it upright.

The shape of the grains are large enough to have space in between them. This means better drainage and aeration properties.

Lastly, though silica is not an essential nutrient for plant growth and metabolic functions, it does make plant cell walls stronger. Stronger plant cell walls means better water and nutrient uptake, and better resistance to the elements and to disease. is part of the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites like mine to earn advertising fees by promoting good quality products. I may receive a small commission when you buy through links on my website.


  1. Only baked, calcium bentonite clay cat litter can be used as a growing medium because it can retain its shape and will not turn into mush.
  2. Used cat litter, in any form, cannot be used in hydroponics or soil cultivation.
  3. Conventional growing mediums are better because they have been tried and tested. However, silica gel cat litter is an experimental growing medium worth considering.


  • “Agriculture Without Soil Offers New Alternatives For Florida Farmers” by Michael Podolsky in Explore Magazine Volume 5(2)
  • “Growing Medium” by n/a in Pacific Bulb Society
  • “Physical and sensory characteristics of cat litter” by Margaret Anne Cliffe in Journal of Sensory Studies 6(4)
  • “Surprisingly, Kitty Litter Is Really Good for These Houseplants” by Teo Spengler in Hunker
  • “The Benefits of Biogenic Silica” by Harley Smith in Easy Grow Ltd.
  • “What is the Best Cat Litter? Non-Clumping vs. Clumping Litter” by Lorie Huston in PETMD
  • “Why Clumping Litters Are Better Than Non-Clumping Litters” by n/a in Home Loving Cats

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