Cactus Potting Soil – Proper Planting Mix For Cacti Plants Indoors

Cactus Potting Soil – Proper Planting Mix For Cacti Plants Indoors

By: Bonnie L. Grant, Certified Urban Agriculturist

Cacti are some of my favorite types of plants to grow inside all year and outside in summer. Unfortunately, the ambient air tends to stay moist during most seasons, a condition which makes cacti unhappy. Cactus potting soil can enhance drainage, increase evaporation and provide the dry conditions that cacti favor. What is cactus mix? This medium promotes optimum health for your cactus and mimics the natural gritty, arid and low nutrient soils they grow in naturally. You can purchase the mixture or learn how to make cactus soil yourself.

Cactus Growing Conditions

The cacti families are succulents which store moisture in their pads, stems and trunks to use during dry and drought periods. They are generally found in desert conditions, although a few are tropical to sub-tropical. The plants favor sunny locations with plenty of heat, areas which have little to no rainfall and harsh soil.

The majority of the family will make excellent houseplants due to their minimal needs and forgiving nature. These hardy plants do need water but not on the scale that the average plant requires. They are unique in form and flower with an ease of care that borders on neglect. They prefer a cactus growing mix that is partially sand or grit, some soil and a pinch of peat moss.

What is Cactus Mix?

Cactus potting soil is available in most nurseries and garden centers. It forms a better basis for cactus roots than regular soil and keeps roots and stems from sitting in moisture, which can cause rot. The right planting mix for cactus plants has superior drainage and will dry out quickly after watering. Cacti will harvest the moisture they need immediately to store in their bodies, and excess water needs to be evaporated or drained to prevent fungal disease and rot.

Commercial mixes use the classic elements these plants grow in naturally and add peat, which tends to hold moisture. Once the peat has dried out, it is hard to get it to absorb water again which makes the pot too dry. The glass really is half empty in this case because not enough water will stay in the medium for the plant to uptake.

Homemade cactus growing mix can be tailor made for any type of cactus. Just like our personal tastes, one mix is not always right for every variety of cactus and growing region.

How to Make Cactus Soil

It is actually cheaper to make your own mixture. If you live in a very arid climate, you will want the addition of peat in your potted plants but be careful and don’t let it dry out completely. In most other areas and in the home interior, the plants are fine with one part washed sand, one part soil and one part gritty amendment such as pebbles or even pot shards.

A very different mix combines five parts potting soil, two parts pumice and one part coir for a mixture that dries out evenly. You may have to tweak the soil recipe depending on where you are using your cactus growing mix and what variety of succulent you have.

How to Know if You Need Different Soil

Sadly, by the time you notice a decline in the health of your cactus and think of repotting it in a different planting mix for cactus plants, it may be too late. A better option is to choose right the first time. Determine where your cactus naturally occurs.

If it is a desert species, use the simplest blend of clean fine sand, grit and soil. If you have a tropical species, add peat.

Plants such as Euphorbia are remarkably adaptable to almost any soil and can even thrive in dry potting soil. Give the plants a hand by choosing unglazed containers that evaporate excess moisture and watering deeply only when the soil is completely dry but not crusty.

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Read more about General Cactus Care

How to Mix Your Own Gritty Cactus Soil for Cheap

After I bought my first cactus, I fell into a black hole of researching everything I could to keep my new cactus plant happy and thriving. This research very quickly took me on a journey that looked like this: buy a new cactus plant, research the new plant, and repeat.

I did everything right—or so I thought. My lighting was actually terrible. The cactus soil I used didn’t drain well enough and resulted in root rot for most of my first plants.

So, I fell down a few more research holes. The first one was: how do I make a gritty, well-draining cactus mix for cheap?

When to Repot a Cactus?

The general rule is to do it as soon as the roots start growing out of the pot. For example, when the roots begin to be visible from below or side aerating holes, it is time to take it out and put it in a new one.

You shouldn’t care only about the size of the cactus, though. The season is also essential. Remember cacti are resistant to drought, so they thrive in hot seasons. On top of that, they grow the most in spring-like most plants. That’s the perfect season to repot them, just before the hot summer arrives.

It is also crucial to mention that cacti grow slowly. In contrast with other plants, they may last between 2 to 4 years in a single pot before needing any repotting. There’s a high chance you will only need to repot a cactus once or twice in a decade.

Choosing Organic Matter Components

When choosing components for your homemade cactus soil mix, the items you choose could affect the overall performance of the finished soil blend. If using a bagged potting soil for part of your mixture, pick a quality variety that ideally doesn't have a lot of peat in it. Peat moss repels water, which means the soil mix won't stay wet enough for the cactus roots to get an ample watering.

Coconut coir, the fibrous material beneath the husk of a coconut, holds water better and is less dense than peat, according to soil company Growers. It's an excellent material to use as one of the organic components for your soil mix. The downside of coir on its own is that it's very lightweight, so if used as a main component, it may not provide ample support to hold up a repotted tall cactus, for instance.

What Kind of Soil Do Cacti Need?

Think about a cactus’s natural habitat. It is dry and hot. It gets water infrequently, but when it does, it gets flooded with water for a short period of time.

This is exactly what you want to simulate when finding potting mix. It should contain some organic material, but be very sandy, or porous. This will allow the potting mix to drain well and provide good aeration to your plant’s roots.

The most common reason cacti die is because of excessive watering or poor potting mix. In both of these scenarios, excess water sits at the roots. This leads to root rot which ultimately will slowly cause your plant deteriorate.

Once root rot sets in, it is difficult to reverse. So it is important to start with great soil and good watering habits.

If you only have one or a few cacti, then I highly recommend that you buy one of the products above. Not only do they have our highest recommendations, but they are also very affordable. They use quality ingredients and tend to have coarse gritty inorganic materials, which allows for optimal drainage.

You can also make your own mix, but if you do not have many cacti, you end up having a lot of extra soil laying around. If you want to keep some for future plants, this may make sense, but generally it is easier just to buy the pre-made mixes.

What is Root Rot?

Root rot is a condition, that if left untreated will destroy your cactus. Because the root rot first starts within the soil, most gardeners are not aware of the problem until it is advanced, and too late. Symptoms that may start to appear include stunted growth or dead leaves.

Once you notice root rot, you need to take action immediately. You likely will need to repot your plant to give it a fighting chance.

The easiest way to prevent headaches associated with root rot is to just get soil that drains well. Soil that is too dense will retain water and allow your plant’s roots to soak in water. This is a breeding source for bacteria and diseases. Cacti, in particular, are prone to root rot. Their natural habitats do not expose them to a lot of water, so they do not have some of the defense mechanisms that other plants may have.

Balance of Organic and Mineral Components

Good potting mix will contain both organic and inorganic (or mineral) components. Organic components refers to things that contains compounds that used to be alive. Mineral components, on the other hand, refers to things that are not made of living substances.

Organic components include things such as general all-purpose soil, pine bark, coconut coir, and compost.

Mineral options include coarse sand, perlite, fine gravel, and chicken grit. You’ll want to avoid mineral components that store water steer clear of vermiculite and clays.

In all of the products above, there is a good balance of organic to inorganic material. In a similar manner, if you want to create your own soil, you will use a combination of organic and inorganic material

Making Your Own Potting Mix

As I said earlier, I encourage you to buy one of the products above. They are very affordable and use quality materials.

If you are set on making your own potting mix, then you can use the recipe below. Just realize that you may be creating more work for yourself and it will likely yield a lot more mix than you will need. You can always keep the excess in storage for when you need it again.

Simply combine these three at a 1:1:1 ratio in a large bowl or container.

Use Pots with Draining Holes

If at all possible, plant in a pot with a draining hole at the bottom. Without a draining hold, still water will just sit at the bottom of your potting mix. Again, this puts your succulent at a high risk of developing root rot.

Unfortunately, nowadays, many pots and terrariums do not have draining holes. It is undeniable, a glass bowl terrarium is spectacular to look at. However, without the draining hole, your cactus will have difficulty thriving. Furthermore, bowl terrariums tend to create a greenhouse type of effect where a lot of humidity accumulates in the bowl. This is, again, not an ideal environment.

If you cannot resist using a pot or terrarium without a draining hole (I get it), then make sure to water very sparingly. It will be difficult to water just the right amount, but try to err on the side of less water.

Soak and Dry Watering Method

The ideal way to water is to use a method called “soak and dry”.

It’s rather simple. Just soak the soil completely and then let it dry out completely before watering it.

When you are doing this method, try not to let water get onto the cactus itself. Also, try to water in the morning so that any water that does land on the plant can evaporate after exposure to the afternoon sun. This will also give your soil time to drain and dry out because of the sun.

You can check out this Youtube video (not created by GreenPinky) for a quick visual guide on how to water your succulent appropriately.

Bottom Line

Again, I recommend buying the Bonsai Jack mix. Don’t make the mistake of buying a cactus soil at your local gardening store that does not drain well and will lead to root rot. Save yourself the headache and buy any of the products above (take a particularly close look at our top 2 recommendations which drain the best).

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About the author: Carley Miller is a horticultural expert at TheGreenPinky. She previously owned a landscaping business for 25 years and worked at a local garden center for 10 years.

Can you use Cactus soil for other plants?

Yes, you can use cactus soil or any cactus mix for other plants. You just have to add some organic matter to provide more moisture retention.

Cactus don’t need much water whereas other house plants like any flowering plant need water at regular intervals. We should always care for the difference in the requirement of these plants.

If you are using the cactus mix for indoor plants then just add 1/3 cocopeat or dry compost to the soil to make it suitable.

The general mix for cactus gets drained quickly. So adding organic matter will maintain the moisture required by other plants.

You should make these changes with the cactus mix to adapt and fulfill the needs of all other plants. After all, The soil is the main component of the sustenance of any plant in nature.

Can Cacti be propagated from seed?

Talk of cactus propagation, and what comes to mind immediately is cuttings, pads and offsets. So can cactus be grown from seeds? The fact is, as much as this may not be a popular form of propagating cactus, some varieties do well when grown from seeds.

Unlike propagation from cuttings, the success rate of using seeds for cactus is lower, and the plant may take much longer to grow and mature. Nevertheless, using seedlings is an ideal way to grow rare cacti species that may not do well with propagation from cuttings or those that do not produce pups of offsets.

The best thing about growing cacti from seeds is that they get acquainted with the climatic conditions from day one. This helps in adaptation to the region and will thus grow much healthier.

Notably, some cacti species can produce seeds through self-pollination. These include such species as mammillaria, Echinocacti and Cereus. However, some cacti species may need some help for pollination to happen. This can be done by shaking the stamens to enable pollen to get into the pestle.

While most cacti species would flower, few end up producing seeds due to challenges in pollination.

When growing cacti through seeds, take the following into consideration:

  • Cacti seeds perform best when sown in early spring
  • Cacti seeds can be pretty tiny, and there are chances of losing a good number. To avoid this, use a white cloth or other material when working on them for better visibility.
  • The best way to find good quality cacti seeds is by buying them from certified dealers. However, you can also collect them from fruits if working on a tight budget.

Propagation of cactus cannot be possible without the right tools and expertise. It all starts with mastering the art of cutting the pieces into ready specimens for planting. Whether you are looking to propagate your cactus through cuttings, pads or offsets, always set the piece aside to callous over before planting. This helps improve the chances, speed and rate of rooting.

The option you choose when propagating your cactus will be largely dependent on the cactus variety and its age. Ensure you have the right information about your cactus species before cutting or propagating the plant.