In some situations, you can add cat litter to potting soil because the clay helps hold in water, and the sand helps with drainage. However, not all kitty litter is a suitable soil additive, and it can harm some plants. Also, it’s not good to add used cat litter to the soil.
Cat litter is absorbent and contains sand, which might make you wonder if you can add it to soil mix for potted plants or use it for drainage or water retention in the garden.
The answer is that many people do mix cat litter into a potting soil mix and garden soil. However, you must be careful to use the correct type of litter and only use it for particular plants that tolerate moist soil.
Also, used cat litter might sound like something you could dispose of in garden soil to add nutrients, retain water, and benefit drainage. However, cat feces contain microorganisms that can transmit diseases to humans, so the best place for used cat litter is in the garbage can.
Only Add Clay or Sand-Based Litters to Your Soil
There are many types of cat litter available, so let’s start by saying that the only kinds of litter that can benefit soil and plants are clay-based litter, sandy litter, and litter that is a mixture of these two materials.
Some clay litter varieties are low-dust, and using one of these brands is better for your health while mixing the litter into the potting soil.
However, litter that contains perfume, dye, or other ingredients is not healthy for plants and should be avoided if you use kitty litter as a planting medium.
If you want to try using cat litter as a soil additive, stick to unscented, low-dust, clay-based, and sandy litter products.
The two most common types of clay in cat litter are bentonite and molar clay. These clays are common ingredients in cat litter, so check the product label to ensure you get the correct type of kitty litter for growing plants.
Cat Litter Improves Water Drainage and Retention
Most clay-based cat litter has two components that can benefit some potted plants: bentonite or other clay that absorbs and holds water and sand, making the soil drain better.
From a cat’s perspective, the clay makes the litter form clumps of solid and liquid waste, making it hygienic to use, and cats like scratching in sand.
Together, these ingredients can also benefit plants that prefer well-drained soil that holds moderate amounts of water.
However, plant roots also need oxygen from the air, and cat litter is designed to absorb a large amount of liquid and hold it tightly. For this reason, the clay part of cat litter can limit oxygen to the plant’s roots. However, the sand component helps aeration.
In addition, clay contains micronutrients such as calcium, iron, zinc, and copper. Some plants can benefit from these minerals, but clay can also prevent other nutrients from getting absorbed by the plant’s roots because the clay clings to specific minerals.
As you can see, using cat litter in soil mix can be a bit complicated. Nonetheless, many people add small amounts of cat litter to potting mix for moisture-loving plants that also like well-drained – but not too well-drained – soil conditions.
Add 25-50% Litter to Your Soil
Pure cat litter as a planting medium is probably not a good idea for most plants. Most people who use litter in potting soil add 25 to 50 percent litter and mix it with potting soil, garden soil, or other horticultural potting materials.
Start Seeds in 3 Parts Litter, 1 Part Potting Mix
Some gardeners report success when starting seeds in a mixture of three parts kitty litter and one-part sterile potting mix. For example, to get this 3:1 mixture, add three quarts of cat litter and one quart of potting mix.
It’s a good idea to moisten the materials to reduce dust while mixing them. Then, stir the damp ingredients together, or pour the mixture back and forth between two buckets, until they are thoroughly blended.
After mixing, you’re ready to put this mixture into seed starting trays or pots and plant the seeds. The clay in the litter helps hold moisture in the soil, but you still need to water the seeds frequently to keep them from drying out.
Moisture-Loving Plants Do Best in Litter Soil Mix
Because the clay in cat litter holds moisture, the plants that benefit most from it like moisture around their roots.
So, in general, the plants that are likely to do best with cat litter need a consistent amount of moisture in the soil.
Here are a few plants that gardeners say grow well in soil mixtures containing some cat litter:
Aloe Vera
This plant does not like too much water in the soil, so don’t use more than about 25 percent cat litter when adding it to the potting soil for this plant.
Ponytail Palm Tree
This drought-tolerant plant is a relation to the Joshua tree. Gardeners report success growing this plant in a soil mix with a small amount of cat litter.
Bulbs
This category includes daffodils like Narcissus species, lilies, and hyacinth. A small amount of kitty litter added to the potting mix can help the soil retain moisture and keep the bulbs from drying out. However, too much litter can cause damp conditions that rot the bulbs.
Succulents
These popular houseplants with thick leaves also like soil that drains well but keeps enough moisture for the plant to survive.
Some gardeners report success with using cat litter for potted succulents.
However, others disagree, so it’s a good idea to research the exact species of succulents you have before planting them in cat litter.
Some Plants Grow Worse in a Cat Litter Soil Mix
Most garden sites say that these plants do poorly when planted in cat litter soil mix:
- cactus,
- bonsai plants,
- and many succulents.
It does not work because the litter holds too much water for these plants, which prefer dry soil conditions.
Nonetheless, some gardeners claim to use cat litter as a top dressing for these species without harming the plants.
Other gardeners say they have added small amounts of litter to potting mix when growing cactus, succulents, and bonsai, and the plants thrive.
The different results might be due to gardeners using different types of cat litter. Other growing conditions, such as air temperature, humidity, and light, might also be affecting the results.
Cat Litter Is Cheap, but Not the Best Choice
The most significant advantage of cat litter for gardening is the low cost and easy availability. Clay-based and sandy litters are inexpensive and easy to find compared to other horticultural products that hold water and improve drainage.
Nonetheless, depending on your situation and the type of plant you are growing, cat litter might not be the best choice because there is so much variation in these products.
The most significant danger is that cat litter can hold too much moisture in the soil, creating mushy, low oxygen conditions that suffocate the plant’s roots.
Alternatives to Cat Litter as a Soil Additive
Here are some horticultural products that have similar properties to cat litter in that they are suitable for improving drainage and water retention.
You can find these products at many garden centers, plant nurseries, and online garden supply outlets.
Vermiculite
This processed mineral looks like mica, and it’s often added to potting mixes because it does not rot or grow mold. It combines characteristics of holding moisture while also improving aeration, making it an excellent medium for starting seeds.
Perlite
Perlite is a white, fluffy, lightweight material made from a processed mineral similar to vermiculite. It improves soil drainage and does not change the pH of soil. Like vermiculite, it’s often added to pre-mixed planting soil.
Pumice
Pumice comes from volcanic rocks, and it’s a popular soil additive for growing succulents. Because it is porous, it can retain moisture and nutrients while still allowing for ample drainage.
Akadama
Akadama comes from volcanic eruptions in Japan. Many gardeners say it is the best planting medium for growing succulents and bonsai. It keeps the plant’s roots aerated while still clinging to moisture. However, this product can be hard to find and expensive.
The Best Way to Know Is to Test It Yourself
Sandy, clay-containing kitty litter has two properties that can benefit some plants: The clay holds onto moisture, and the sand allows for drainage. However, there is a lot of variation between cat litter brands, and a given brand might or might not be suitable for a particular plant.
If you are curious about using cat litter as a growing medium, the best approach might be to start small with one plant and see what happens. Then, if it works for you and the plant, you’ll have an inexpensive and readily available potting mix additive you can try on other plants.
