DIY: How To Make Cactus Soil

DIY

Last Updated - June 13, 2022

Cactus plants are the easiest types to grow, and they are perfect for beginners. They are unique and beautiful, and there is a lot to love about these potted plants. Available in various species, from desert species to forest cactus, the possibilities are endless. While they look vastly different, all of these cacti plants require well-draining soil mixes. By making your own cactus soil mix, you can save money and fine-tune the ingredients in your mix to best fit the type of cactus you have. Below, we'll share how to make cactus soil at home.

Basic Elements Of Every Cactus Soil Mix

All of the ingredients needed to make a soil mix suitable for your cactus plant are available for purchase at your local garden center. You can mix these ingredients in different combinations to create different soil profiles. The most important features of any cactus soil are that it has excellent drainage and proper aeration. You want to have the right ratio of inorganic material and a small amount of organic material.

Regular Potting Soil

This serves as the base of your potting mix. Any regular potting soil you happen to have on hand will work, as long as it is both fresh and sterile. If possible, choose a light and porous potting soil. Avoid any garden soil mix that is heavy. Likewise, avoid any mix with vermiculite or any other addition that is intended to hold on to moisture.

Perlite or Pumice

It looks like styrofoam, but it's real stone! Perlite and pumice keep the soil mix from becoming too dense and increase soil aeration and drainage. A soil mix that drains excess moisture easily is crucial for cacti plants. They are prone to moisture-related diseases, such as root rot, and require soil that doesn't hold moisture for long.

Coarse Sand

Despite popular portrayals, cacti don't thrive in pure sandy conditions. However, all cactus types require sand to some degree. You can use any coarse sand, and avoid sandbox sand, as it is too fine. Also, avoid sand from the beach, as you don't know what bacteria or microbes you'll be introducing to your soil mix. If you can't find suitable sand, you can substitute chicken grit.

Gravel or Lava Rocks

These work similar to sand. Gravel and lava rocks are intended to help keep the potting mix loose and full of air. Many cactus growers will use sand for desert cactus species and gravel or lava rocks for forest species.

Peat Moss

Cacti are considered low maintenance, but they can actually be pretty picky about their soil. This includes a soil's pH level and moisture level. If your soil mix has a high pH level, adding a small amount of peat moss will help lower it. You can substitute peat moss with coconut coir or orchid bark if needed.

Cactus Soil For Desert Cactus

Desert cactus needs more than just pure sand! Sand is great for aeration, but it doesn't provide nutrients. You'll need to combine the elements listed above to create a well-draining, rocky, nutrient-rich cactus mix. A basic cactus soil recipe for desert plants is:

  • 3 parts bagged potting soil
  • 3 parts sand/gravel
  • 2 parts perlite/pumice

In a bucket, begin by mixing together the potting soil and the sand or gravel. Be sure to mix the two elements very thoroughly - this can take multiple minutes! Then add the perlite or pumice, and again, mix very thoroughly. After your cactus soil is adequately mixed, check its pH level using a pH measuring meter (available at many garden centers). If the pH is too low, add a small shovel of peat moss. Retest after mixing, and keep adding more peat moss until you get the pH reading that you need.

When you go to plant your cactus using your own potting mix, be sure to choose a pot with drainage holes that are of ample size. Desert cactus roots can reach down 3 feet deep and spread out just as wide in search of water.

Cactus Soil For Tropical Forest Cactus

Tropical forest cactus (often called jungle cactus), such as Christmas cactus and Easter cactus, actually grow in rainforests. They don't have spines and have slightly different soil needs. In their native environment, they grow in trees or on rocks and get their nutrients from the build-up of organic materials that collect in cracks and crevasses. Cacti soil for these types of houseplants also requires ample aeration to prevent root rot but also needs more organic matter. You will need:

  • 3 parts regular garden soil mix
  • 3 parts sand/gravel
  • 3 parts perlite/pumice
  • 2 parts peat moss/orchid bark/coco coir

You will mix up this forest cactus soil similarly to the desert cactus soil above. In a bucket, mix the regular potting mix and the sand or gravel thoroughly. Then, add the perlite or pumice, and again, mix thoroughly. This can take up to 5 minutes to do correctly!

Now, you'll add peat, bark, or coconut coir. In this case, adding this element is not so much to correct pH levels as adding extra good aeration and organic matter. This simulates the dead leaves and debris that would supply the nutrients in their native habitat. Coconut coir is a great addition to forest cactus, and the slow decomposition of coconut coir will help the cactus mix hold moisture while providing structure. If possible, add a scoop of bat guano or oak leaf mold as well!

Once the cactus soil has been mixed, choose a large pot with drainage holes. The roots of forest cacti don't drive down as deep, but they are accustomed to not being underground at all! You need to give them ample room to spread out within the pot.

5 Tips For Making The Best Cactus Soil

A Balanced Organic And Inorganic Matters Ratio

The perk of purchasing store-bought cactus potting mixes is they will have balanced organic and inorganic materials. When making your own soil, note the type of cactus you have and determine the right planting mix.

Cactus soil should be composed mainly of inorganic materials with a small number of organic materials. If you have too little organic matter, it will retain too much excess water and won't completely dry out between watering. And if you have too much organic matter, water in the soil drains out too quickly for roots to absorb water.

Test pH Level

Before using your cactus soil and planting your cactus, it's best that you test the pH level first. Almost all types of cactus require slightly acidic soil to thrive, and some may require a higher acidity than others. If the pH level of your soil is too high, it can kill your cactus.

Moisten Your Garden Soil

Before mixing, moisten your garden soil first before mixing to prevent dust from coming out of the container.

Nutrient Content

Cacti do best in nutrient low nutrient soil. While they do need to be fertilized once or twice a year, they should not be grown in a nutrient-rich environment.

Sterilize Before Use

While making your own cactus soil is a good idea, you also don't want to expose your cactus to bacterial or microorganism growth in the potting soil as cactus are super sensitive. Therefore, the best soil mix should be sterilized before use.

To sterilize the soil mix, place the soil in a pot or glass container, then put it in another larger pot with hot water and keep it in slow cooking mode until the larger pot reaches the boiling point. This method is commonly referred to as the bain-marie sterilization method or the double boiler method.

You can apply this method to commercial mixes to ensure that the soil doesn't contain any contamination that can cause infections to your cactus.

How To Properly Store Any Leftover Soil

The best part of making your own mix is you can make a big batch, and most likely, you will have leftover soil. It is easy to store any leftover cactus soil in your garage, basement, or garden shed. Ensure you store the potting mix in an air-tight container to keep any bugs out.

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About the author

Bella Zinti

Bella has a Bachelors degree in interior design, is a master gardener with extensive experience building homes from scratch. She designs nourishing outdoor & indoor spaces guided by the practice of Feng Shui, as well as helping clients create year-round sustainable organic gardens.

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