What is Cactus Soil and How Does it Differ From Regular Potting Mix?

Cactus soil and standard potting mix are not the same and it helps to understand the differences. Certain plants, like cacti, have unique soil needs, and regular potting soil or potting mix is often insufficient to help the plants thrive. Read on to learn how cactus soil differs from regular potting mix and why it's the key to growing happy, healthy cacti indoors.

What is Cactus Soil?

Cactus soil, or cactus mix as it is sometimes called, is a blend of mainly inorganic materials such as sand, gravel, pumice, and/or perlite. These materials have superior drainage qualities to prevent plants from sitting in soggy, waterlogged soil which could result in root rot. Cactus soil is ideal for growing cacti, succulents, and bonsai trees thanks to its superior drainage. 

While cactus soil is often used to grow other succulents, many of these plants are not as drought-tolerant as cacti. Some cactus soil labeled as appropriate for both cacti and succulents may contain a little more organic matter, such as peat moss, mixed in for the succulents. If you have this type of soil for a cactus houseplant, add a handful of coarse sand, grit, or perlite for better drainage.

In addition, do not confuse cactus soil and orchid mix, either. Orchid mix is well-draining but contains organic elements, such as peat moss, bark, and sphagnum moss, all of which retain more moisture than cacti need.

Why is Cactus Soil Beneficial?

Cactus soil is beneficial for growing cacti for several reasons:

• It mimics the native environment in which these desert plants are accustomed to growing.
• Cacti have shallow, delicate root systems that will not thrive in potting mediums that are overly dense or hold onto water.
• Cacti are also drought-tolerant and easily susceptible to root rot, meaning they won’t grow well in soil that is high in organic matter and holds excess moisture around the roots.

Cactus soil mixes, which are actually "soilless" mediums, address all of these unique needs and are formulated specifically to help cacti succeed when grown indoors. Regular potting soil is not suitable to provide these desert dwellers with the conditions they need to thrive.

Differences Between Cactus Soil and Regular Potting Mix

There are several key differences between cactus soil and regular potting soil or potting mix.

• Composition: Regular potting mixes are high in organic matter such as peat moss, compost, and coco coir, which are ideal for most foliage plants. Cacti don’t require the same levels of organic matter and cactus soil contains inorganic materials such as perlite, pumice, grit, gravel, and/or sand.
• Moisture retention: One of the biggest differentiators between cactus soil and regular potting mix is its moisture retention. Regular potting mix usually drains well, but the organic materials in the soil soak up and retain moisture. Cactus soil does not retain moisture because it is primarily made up of inorganic materials, which also helps to prevent root rot.
• Aeration: Regular potting mix is dense. Cacti have delicate roots that grow best with proper air circulation so cacti soil is less dense to improve aeration for the roots.
• Drainage: Regular potting mixes are not designed to drain as quickly. Cacti need a potting medium that drains well and dries quickly to mimic the desert environment, which has long periods of drought and short bursts of moisture. Cactus soil drains quickly but retains enough moisture to allow the roots to absorb what they need first.
• Nutrient content: Regular potting soil is rich and is often amended with additional fertilizers to boost plant growth. Cacti are not accustomed to rich soils and do best in nutrient-poor mediums. 

How to Make Your Own Cactus Soil

Purchasing a pre-made cactus soil ensures that it contains everything the cactus needs without much work on your part. Pre-made cactus soil contains the right ratio of inorganic materials (perlite, pumice, sand, and gravel) as well as a small amount of organic material such as peat moss or coco coir.

However, making your own cactus soil mix is also an option and it is easy to do. Simply mix 3 parts potting soil, 3 parts coarse sand, gravel, or horticultural grit (do not use sand or grit from your garden because it is not sterilized), and 2 parts perlite or pumice. Don't use a potting soil mix that contains fertilizers because the fertilizer can burn cacti roots and cause leggy growth.