How to Pick The Best Soil for Cactus | The Soil Guide

Does Cactus Require Special Soil?

In short, yes, it does. Since regular soil can hold too much moisture, cacti need special soil. Soil that is light, sandy, and pebbly helps cactus roots get the moisture they need without holding on to this extra moisture. Excess water should drain away from the soil after watering, thus avoiding root rot and fungal diseases.

Cacti need a soil mix that can dry quickly after watering and fulfill the cactus’s nutritional needs.

The Perfect Soil For Cactus

The best soil for cactus should be light and airy. With potting soil, mix grit, gravel, or similar ingredients to create an ideal cactus growing medium. 

A Cactus Mix?

If you didn’t already know, cactus has its own store-bought soil mix that you can just buy, so that’s good news! Cactus mix is a type of soil made specifically for growing cactus. You can find these in most nurseries and garden centers. Of course, you can also make the mix yourself (we’ll get into details later). 

Ideally, the mix should be able to drain and dry quickly after watering. That is because cacti take in all the water and store it after watering, so you need soil that can drain the excess water pretty quickly to prevent any root rot or fungal diseases. 

Commercial cactus mixes are meant to mimic the natural habitat of cactus, so they come with peat that can hold moisture. When the peat absorbs water and dries out, it doesn’t soak in water, leaving the pot dry.

If you choose to make it at home instead, be mindful that no single mix is suitable for all cacti, and the one you make can differ from the commercial ones. 

The perfect cactus soil mix also depends on the area you live in and the natural conditions of the cactus. Since the natural conditions of tropical and desert cactus differ, you can’t use the same mix for both.

Do You Really Need A Cactus Mix?

If you want a healthy, blooming cactus, yes. For cacti to adapt to their harsh environment, they possess waxy coats and succulent tissues to store the water they need, and guess what… The roots of desert cactus have adapted as well, which is why you’ll need a quick-drying potting mix.

Cactus roots are prone to rot when soaked in water. Cacti have shallow roots that stretch and can hold water for a long time, allowing them to absorb enough water to thrive through long periods of time. If there are any changes in the water supply, the roots have the ability to adjust quickly.

While they can retain water for long periods, cacti can rot quickly if they live in a pot that doesn’t have adequate soil for them. Thus, it is crucial that you make sure the soil meets their nutritional needs! 

How To Choose The Best Cactus Soil

There are several elements of the soil to be aware of if you want to have the ‘best’ cactus soil, all of which are important, so don’t skip any of them! 

Organic or Inorganic?

Soils are classified as mineral or organic based on their content of organic matter. Mineral soils make up the majority of farmed land on the planet and can include anything from a trace to 30% organic matter. Organic soils are naturally high in organic matter for a variety of reasons, mostly climate related. 

Because organic matter in soil is mostly composed of plant residues, it includes all of the plant’s necessary nutrients. Another great thing about organic matter is that it allows water to penetrate more quickly into the soil.

Some examples of organic matter are peat moss, ground bark, and ground coconut fibers. Peat moss is found in soil mixes such as Perfect Plants, Hoffman, and Miracle-Gro.

Careful, though, organic matter can retain a lot of moisture, so keep that in mind! 

On the other hand, inorganic soil ingredients are great for cacti since they help the soil drain more easily. Perlite and sand are examples of inorganic soil ingredients. Overall, cactus potting mix should include more inorganic matter (like perlite and gravel) than organic matter.

Well-Drained Soil Is the Best 

Overwatering is a big risk that cacti face. When you overwater your cactus, it’ll tell you to stop through some crystal clear signs, like root rot, a pale or black base, and change of color in the leaves. 

Unless you want your cactus to die, you shouldn’t get soil that is not well-drained and retains too much water.

The perfect composition of soil should be gritty and pebbly. You also want soil that is aerated and drains properly. 

Don’t Forget about pH!

Typically, cacti are pretty strict about living in soil that has the right pH. It should not be too acidic; a pH of 5.5 or 6 is ideal for your cactus and it will thrive. If you notice your cactus isn’t growing, there could be something wrong with the pH balance in the soil, which increases its alkalinity.

It’s also possible that the cactus isn’t growing because it isn’t absorbing the nutrients it needs to thrive. Rainwater is great as it maintains a balanced pH in the soil. If you want to, there are several types of pH testers available in the market that may be used to check the pH of your soil.

The best thing about purchasing cactus mix is that they are already designed to have the perfect pH. 

Testing the pH Level

Start by digging a hole and removing any large debris.. Fill the hole with distilled water (you can find it at any local pharmacy) until it gets muddy at the bottom. Insert your clean tester probe into the muddy pool, now you need to hold it there for one minute before taking a reading. 

Typically, the tester uses a scale of 1 to 14. The pH value of 7 is considered neutral. It is alkaline if it is over 7, and acidic if it is below 7.

How To Use pH Test Strips

You can purchase test strips or litmus paper at the garden store. To perform the test, take a little bit of the soil in a bowl and mix it with distilled water, then give it all a good stir to ensure it’s evenly mixed.

Dip the test strip into this mixture for around 20 seconds while holding its non-reading end (refer to your test strip’s instructions as the time in the bowl will differ based on its type). 

When the timer goes off, dip your test strip in distilled water for a few seconds to remove the dirt. Check what color is closest to your result using the key that comes with the strip.

You can also reduce the pH of your soil to make it closer to being acidic, which is perfect for cactus. Add 1 cup of organic matter (like peat moss or decomposed leaves) to your soil. Keep doing that until you reach the ideal pH level.

The Most Commonly Used Soil Ingredients

Will your cactus be healthy or not? This is determined by the soil mix you’re using. So, make sure to pick the right one!

For enhanced drainage, mix grit and gravel into your potting mix. If you go with sand, make sure it’s construction sand, which is gritty and cheap.

Japanese Hard Akadama

Its origin, as the name implies, is Japan, and it is only mined there. People use this clay-like mineral to make potted plant soil.  It can be used alone or in combination with other substances (like sand) to make a rich soil.

Akadama has the ability to hold water and nutrients while also breaking down, allowing the roots to develop and preventing water from staying around the roots, which lowers the risk of fungal diseases and root rot.

Pumice

Pumice is a light gray volcanic rock with empty gas bubbles that allow the rock to float on water. Being porous makes it an excellent ingredient in cactus soil. It’s added to potting mixes to increase drainage. 

This rock is great since it’s loose and increases airflow, it leaves good space for air so that it keeps enough moisture, reducing the number of times you need to water your plant and reducing the risk of root rot. Typically, pumice will make up 25-30% of a potting mix.

Perlite

Perlite is a white volcanic glass that contains high amounts of water. This glass is used in making potting mixes for cactus plants or any other succulents that don’t need much moisture. Perlite has great aeration properties and has a neutral pH.

Perlite is useful since it drains excess water while holding moisture, leaving the soil dry and ideal for cactus to thrive in.

Grit or Gravel

Another element in a well-draining potting mix is grit or gravel. You can use aquarium gravel, poultry grit, granite pieces, or crushed limestone. Any inorganic material that does not hold water and generates an aerated soil is ideal.

Gravel or grit can be found in  garden centers, DIY stores,  home improvement stores and online stores.

Vermiculite

Vermiculite is a kind of laminar hydrated mineral. It generally has a pH of 7, meaning that it is neutral. Since it’s a light mineral, it blends in well with the rest of the soil’s components.

It helps plants absorb magnesium, calcium, ammonium, and potassium. It can be added to soil alongside peat to boost the roots growth. In potted plants, mix half soil and half vermiculite to absorb excess water and provide aeration.

Commercial Cactus Mixes

The numerous choices of cactus mixes on the market can be overwhelming. At the same time, you want to pick the best among them, so hear us out! 

Some mixes may not suit indoor planting, so to increase the porosity of the soil, you might find yourself wanting to add coarse materials like pumice even after purchasing. 

If you are not confident in your ability to make your own cactus potting mix, then commercial cactus mixes are the way to go. 

We recommend you to try out some well-known commercial mixes like Hoffman Organic Cactus and Succulent Mix, Espoma Organic Cactus Mix, and Green Planet Naturals Cactus Mix with Mycorrhizae.

You want to look for a potting mix that drains and holds water well. When they dry out, they don’t fully dry out, leaving some moisture for the roots. Eventually, your plants will absorb the water they need and store it in their bodies, while the excess water will drain out via the pot’s drainage hole. This is why you should also consider drainage holes when purchasing a pot.

Since most mixes just contain the fundamental ingredients of potting soil, you’ll need to add peat moss to improve it. Cacti will develop from propagation to maturity in these mixes.

Cactus Potting Mix & Cactus Type

To decide which type of soil your cactus needs, you first need to know which type of cactus you’re going to plant. 

Tropical Cactus

Tropical cactus can naturally be found in the jungles of South America. This type of cactus grows on trees (they are epiphytes). Holiday Cacti, such as the Christmas Cactus, are examples of such species. In contrast to the arid cactus, these cacti are soft and have spineless leaves.

Even when it rains, cactus drain well since they are attached to trees, and their roots cannot rot. As a result, they require consistently wet soil that drains very well and does not get waterlogged. 

Almost all cactus species require soil that drains well. Tropical cactus, though, requires more organic matter in its soil than other cacti. You can make a mixture of 1 part garden soil, 1 part sand, and 2 parts peat moss.

Arid Cactus

Arid cacti, which are native to deserts, need dry soil to thrive. They absolutely hate overly moist soil, which causes root rot. Make your own mix by using 1 part soil mix with 2 parts sand to provide these cacti with the most natural-feeling environment for them to grow.

Though arid cacti have spines as a defence mechanism to keep predators at bay, certain animals (like camels) are brave enough to consume them in spite of their spines!

How To Make Your Own Cactus Mix

Don’t want to purchase a commercial cactus mix? Not a problem, you can make it yourself! And the best part is that you can customize your mix to fit the needs of your own cactus. Just get a big container to avoid spillovers and prepare the following ingredients.

Ingredients:

• 1 part builder’s sand
• 5 parts perlite
• 4 parts bagged potting soil
• A little bit of rock dust

Jungle Cactus Recipe

As we mentioned before, the potting mix used for desert cactus is not the same as the one used for jungle cactus. You’ll need a specifically customized mix because jungle cacti are epiphytic, meaning that they can grow on rocks.

Dead leaves can provide nutrition for these cacti. And it’s also great that they’re able to get the amount of air they need.

You want to make soil that can mimic these conditions as closely and as naturally as possible. To make it, combine coconut coir, peat moss, orchid or fir bark, pumice, and oak leaf mould.

This mix is similar to the dry mix, but with a few differences. You need one part pumice and two parts orchid bark (coarse). This mix increases aeration, which is great for your tropical cactus.

Desert Cactus Recipe

Cactus won’t grow properly if planted in pure sand. Opt for a rocky, nutrient-rich soil in a pot with enough drainage holes. 

Peat moss, coconut coir, perlite/vermiculite, and pumice are some of the nutrients you’ll need. All of these ingredients together make an ideal potting mix for cactus.

For your base, use regular potting soil. Then, since pumice is a light, porous volcanic rock, add two parts of it. If you don’t have pumice, you can use chicken grit instead. Perlite or vermiculite can also be used as a substitute. Now pour some coconut coir in as it decomposes gradually, this will help the mix to hold moisture.

A good Alternative for Tropical and Arid Cactus

Ingredients:

• Ground fir bark
• Bucket
• Peat moss/coconut coir
• Vermiculite/pumice//perlite/coarse sand

Mix the same amount of peat moss with ground fir bark in a bucket, making a mixture that is suitable for both tropical and desert cacti. Instead of peat moss, coconut coir or ground fir bark can be used as an alternative.

Then, mix 1 part of the coarse builder’s sand with the base potting mix that you made. This applies to tropical cacti, which need more moisture and can withstand slower water drainage than desert cactus. Instead of coarse sand, you can opt for perlite, pumice, or vermiculite.

Desert cactus can’t tolerate too much moisture retention, so it thrives in a mix that is able to drain water quickly. Thus, you should use equal portions of the coarse sand or perlite/pumice/vermiculite and base potting mix, and give them a good blend until they’re evenly distributed. If you find any lumps left, it just means that you need to keep mixing! 

To ensure that the cactus is safe to plant, squeeze the soil to make sure that there are no excess droplets. When watering, you can mix one tbsp of vinegar to 5 gallons of water and add it to the soil. This will slightly increase the acidity of the soil.

Bottom Line

To keep the cactus roots from decaying, the soil must drain quickly. Repotting and trimming the damaged roots is a great root rot remedy. The soil should be able to effectively retain moisture so that it can supply for the plant if it becomes dry.

Choose a soil that is high in nutrients, porous, and has inorganic materials for appropriate drainage, and organic components to supply nutrients to the roots when they are in need. When using regular potting soil, add some pumice to increase the soil’s capacity to drain water. 

Keep in mind that you’ll need to repot your cactus every 2-4 years, you know it’s time to repot them once the roots start to show through the drainage holes.

When it comes to buying a potting mix for your cactus, or even making one yourself, the information and instructions provided in this article will help you provide your cactus with the environment it needs. And finally, always know that there’s no one universal, one-size-fits-all recipe for cactus potting soil. The best recipe for your cactus partly depends on your own plant and your personal preference, and our recipes are just a general guide for a well-balanced cactus soil!

Find out more about the ideal environments to grow cacti in our article here!