Tony O’Neill, gardener and author of the popular “Composting Masterclass” and “Your First Vegetable Garden,” combines lifelong passion and expert knowledge to simplify the art of gardening. His mission? Helping you cultivate a thriving garden. More on Tony O’Neill
This post will address cactus compost to include succulents, of which cacti are a single subgroup. All cacti are succulents, but not all succulents are cacti. Growing cacti is an enriching hobby – or business. With over 10 000 species, there is great variety and beauty.
Cactus compost refers to the growth medium used for cacti or succulents. Experienced growers insist that making these mixes is part of the craft, creating a species and age-specific balance between pH, nutrition, and drainage.
Cacti are growing in demand, with 3,000 species requiring protection under the CITES (Convention on the International Trade of Endangered Species). As a valuable commodity, you want to ensure you grow them right, and this post will help you do that.
Endangered Cacti and Succulent Plants
CITES protects four major succulent plant groups:
- The cactus family (Cactaceae); Cactaceae is by far the most prominent and best-known group and includes over 2,000 species.
- The succulent Euphorbia species (Euphorbiaceae) include over 700 succulent species from 2,000 in the Euphorbia genus.
- The genera Aloe (Liliaceae) – 400 species
- The Pachypodium (Apocynaceae) – 14 species
Every North American and European home has had a cactus plant on its kitchen window sill – most likely a brightly flowered cultivar of Schlumbergera, the Christmas Cactus.
What is cactus soil, and what do Cacti look like?
Cactus soil is a growing medium designed with specific characteristics to ensure a suitable growing medium for cacti. Standard compost should not be used. However, your composting efforts are not wasted, as compost can be used as an ingredient in your cacti compost mix.
Except for one genus, cacti are unique to the Americas. Stems distinguish the Cactaceae family with specialized felted discs called areoles that grow spines, special to this plant family.
Mexico and the nearby southwestern United States are the “hot region” for species variety, with approximately 30% of cacti genera being endemic and nearly 600 native species. Secondary diversity hotspots include Brazil, northern Argentina, Bolivia, Peru, and Chile.
For example, the consumer market for succulent plants has been fueled by the demand for desert plants for landscaping.
TRAFFIC Between 1998 and June 2001, North America estimates that they gathered almost 100,000 succulents worth $3 million in Texas and Mexico to feed the landscape garden market in Phoenix and Tucson.
In the Aloe market, Canada, the Republic of Korea, and Spain have exported the most significant quantities of artificially propagated plants. The major markets for live plants are the United States of America, China, and Switzerland.
Deserts are very dry places, but plants can still grow there. Desert plants collect and use water in special ways.”
– Julie Penn
Suitable Cactus Potting Soil Ingredients That Can be Added to Compost
Generally, succulents need nutrient-rich, well-drained soils. You can get an optimal DIY cactus soil mix by combining different ratios of organic and inorganic matter (often called grit). What the balance ought to be and what elements should be present seems to be a matter of opinion, even among specialists.
The fun part is developing what cacti compost works for you. Below I provide quite a bit of guidance and some base mixes which you can adapt for your use when you grow cacti.
A word of caution: commercial cactus compost claiming general purpose is a possible starting point, but mixing your own is better. You want to focus on how much organic matter and drainage your cacti soil has. Also, you will want to avoid unquantified fertilizer inclusion. Ideally, briefly explain at home you want to be in control of as many variables as possible.
Standard compost materials for your cactus are listed below in the two groups, with a brief explanation of each’s function in the mix.
|Turface for Plants MPV
|Carbon Activated CocoPeat
Cactus Potting Soil / Regular Potting Soil Ingredients for Cacti
Coir helps retain water in dry soil, improves soil drainage, is slow to break down (4 years), and creates pockets of air around the roots of plants, allowing excess moisture to drain away. It is 100% organic and eco-friendly, free from soil-borne pathogens and weeds. It has a pH of 5.5 – 6.2. It is a perfect ingredient when making a cactus compost mix
Can you Use Normal Compost?
Made from decomposed organic materials, compost enriches and enhances the soil. Plant nutrients and helpful organisms like worms and fungal mycelium are abundant in the final combination. Compost promotes soil fertility in gardens, landscaping, horticulture, urban agriculture, and organic farming.
Ordinary compost should not be used alone but should form part of the cactus compost mix you are designing for your cacti.
These are items like barks and leaves in a state of semi-decomposition. Semi-decomposed leaves and bark can act as a water-storing sponge. Forest products provide nutrition and good drainage by bridging the gap between organic matter and grit. Ideally, the particle size should be limited to a quarter-inch and exclude dust.
Dust will create compaction in your cactus compost mix and prevents air from moving through the compost.
Potting soil provides soil with increased organic matter and drainage. Typically, potting soil may have some perlite included. Some potting soils may consist of fertilizers and are not suitable for succulents.
Adding Top Soil
Topsoil is a cheaper option than potting soil. Topsoil comes from sites where the top 4 to 6 inches of the surface have been removed, commonly using a grader, and then bagged for resale. Interstate regulations exist for soil migration.
Topsoil includes less organic matter than potting soil and thus has poorer drainage capacity. Some purest insist on its inclusion in the compost mix for fear that commercial potting soils may include fertilizer. Excess nitrogen causes succulents to have misshaped leaves.
When using potting soil, rinse it and let it stand in the sun for 3 to 4 days to sterilize it, stirring it occasionally. If the weather isn’t conducive to this process, fix the soil in an oven for 20 minutes at 200 degrees Fahrenheit, stirring it occasionally.
Including kelp pellets or granules in the mix is an excellent fertilizing option. Kelp typically has 4 percent nitrogen, no phosphate, and 2 percent potash, and its inclusion in a blend is less than 5 percent of the total compost mix volume.
Carbon Activated CocoPeat
I have read that some growers include a carbon-activated cocopeat – a coconut coir brick with some activated carbon. Food manufacturing processes commonly use activated carbon, mainly as a filter, and its use in horticulture is gaining popularity as a pathogen inhibitor.
I added peat moss to the list to have the opportunity to advise you NOT to use it. Peat moss has a low pH (acidic), and most succulents prefer a pH range between 7 and 8 (low alkalinity). Also, peat moss can cause anaerobic conditions – something cacti cannot tolerate.
Ideally, you should not add peat moss to the cacti compost mix for this reason alone. If you decide to add it to your cactus compost mix, you should add plenty of chunkier ingredients to ensure adequate air movement and drainage in the cactus compost mix.
Inorganic Materials to Use In Making Cacti Composts
Perlite is an amorphous volcanic glass that has a relatively high water content. Heating the crude rock to 1600 degrees Fahrenheit causes it to pop like popcorn resulting in a light material with excellent water absorption properties.
Perlite particles also interface with each other and other soil constituents to create air passages. These air passages provide oxygen to roots and allow excess water to drain rapidly.
Do not use fine sand or beach sand. The coarser, the better, and it must be able to aid in better drainage.
Decomposed granite is a product of the effect of weather on granite blocks. Use pebbles not more significant than a quarter-inch in diameter for aeration and to assist drainage. If you sieve it and get a slightly larger couple, use them to create a rocky aesthetic cover that will prevent rapid evaporation from the soil.
Instead, use decomposed granite as the gravel may have sand particles. Washing it and leaving it to stand in the sun for three to four days to sterilize is a solution. Particle size should be less than a quarter of an inch in diameter.
Chick grit is typically fed to chickens to help process food in the giblet. It has an orange color and can either assist drainage or aeration. It is also a decorative feature on the surface, creating an excellent color offset to the succulent’s color.
Turface for Plants MPV
Turface is a brand name for a product commonly used on baseball pitchers. Often referred to as fired clay, it contains silica and bentonite – both ingredients for moisture-regulating potting soil.
With a total porosity of 74%, this product is a favorite for many succulent growers. The MPV version seems to be preferred.
- has good insulating properties,
- increases soil porosity,
- absorbs 38% of its weight in water,
- durable for decades,
- does not change pH,
- improves drainage and aeration (retains 30% air space),
- 100% inert and inorganic, so it does not decompose
Expanded shale can soften up hard clay soils and make them more workable. Its porous structure allows aeration from shale particles, resulting in a more widespread and healthier root system in poorly aerated clay soils.
Pumice is solidified foam that forms from lava rich in gases, and it has numerous pores in the form of bubbles and irregular cavities that absorb moisture. For planting succulents, you want a 3/8 x a quarter-inch mix.
Composting Essentials and Other Factors When Growing Cacti in Compost.
Succulents grow naturally in desert conditions, the Alps, and jungles. Each group has developed unique adaptations to survive often harsh environments. What sets succulents apart from other plant species is their ability to store water – up to 99% of the plant may be water. For the most part, there are three environmental elements to consider for a thriving cactus growing experience. These are:
Let’s look at the three environmental elements in these climates; Semidesert, Alpine, and Jungle.
Semidesert Climate and Other Succulents
Except for one genus, Rhipsalis, which has a distribution that stretches from South America to southern Africa and Sri Lanka, cacti are unique to the Americas. Stems distinguish the Cactaceae family with specialized felted discs called areoles that grow spines, unique to this plant family.
Desert cacti thrive in arid regions but not in desert dunes. The belief that cacti can survive without water for extended periods is inaccurate.
In layperson’s terms, there are three groups of semidesert cacti:
- small rounded, flat, or cylindrical plants
- shrubby, segmented, and sprawling kind
- large columnar and tree-like giants
The guides within this article are generalized for a regional-specific growing environment. The tricky part of successfully propagating these plants is taking the provided guidelines and adapting them slightly to your environment and species.
Cactus Compost For Semidesert Cacti
Most cacti prefer nutrient-rich, rocky soil with good drainage. We’ll utilize some of the same components I used for the jungle cactus and some new ones to make a proper growing environment for our desert cacti. Below is a cactus soil recipe to help with semidesert cacti.
I use a simple, well-draining blend of a 50/50 split of organic/inorganic materials for semidesert climate cacti.
- 25 percent Potting Mix with no added fertilizer
- 25 percent Coconut Coir
- 20 percent Expanded Shale
- 20 percent Turface
- 10 percent Pumice
Don’t be tempted to switch the potting mix with peat moss. Peat moss is hydrophobic and difficult to re-wet. Also, be sure that the potting mix does not have any added fertilizer, as this will negatively affect the leaf growth of your succulents.
Ideally, a terracotta pot allows air and water movement through its walls. All pots must have draining holes, and these should not be covered. Test your mix for water retention and flow. Do not use stones or pebbles at the bottom of the pot.
When watering your pot, water should not sit on top but readily flow through the planter. Due to capillary action, some water will remain in the soil, but your mix of coconut coir and the other gritty material will ensure that the roots are not soggy yet retain some moisture.
How much water do semidesert cacti require?
Cacti’s ability to thrive in scorching, arid, and harsh environments is remarkable. But they need water – water is essential for all cacti to live. Their ability to survive where water is scarce or given infrequently has earned them a reputation for drought resilience.
Most desert cacti can withstand prolonged drought, mainly because they crammed as much as possible into their tissues the last time they had access to water. Cacti also have several characteristics that allow them to retain moisture and avoid drying out in hot environments.
When the earth is dry, it’s an excellent time to water desert cacti in a pot or on the ground. Watering once a week is suitable in hot, dry locations such as southern California in the summer. The soil may take three to four weeks to dry out enough to yield more water in more humid or incredible places.
The goal is to minimize overwatering rather than avoid watering altogether. It is still preferable to submerge rather than over-submerge. If the soil is still wet, don’t water it. There are exceptions to every rule, so you’ll have to experiment to find the optimal watering regime for your plants, just like you did when picking the correct soil.
Stand the pot in a water bowl up to the soil level until the soil mixture is soaked, then remove it and allow it to drain freely. (Try not to forget about the planters in water; otherwise, they may decay.) Use your finger to feel the soil once the top half-inch of the potting mixture is dry again.
Do not spray mist these plants; they are desert, low-humidity plants.
Different Light Requirements for Cacti
In contrast to jungle cacti, desert cacti prefer a lot more light. Potted plants, seedlings, and newly rooted cuttings should only spend half the day in the sun, and the light would quickly destroy plants that aren’t well-established.
As a result, it is not a good idea to transfer cacti into direct sunlight until they have established a healthy root system. Avoid full sun even for established potted plants.
You’ll rarely find a position where your cactus gets too much light if you’re growing your potted plants indoors. The inverse will rather be true. You may use full-spectrum fluorescent lights to augment or replace sunlight when natural light is scarce.
If your cacti require extra light, you’ll be able to notice right away. Cacti with insufficient light will have thin, stretched-out growth.
Alpine Climate Succulents
All the succulents that grow in mountainous regions require loose soil that is often volcanic. The most significant risk to their perishing is lack of light or overwatering. A typical mix for the plants that grow in mountain regions would be well-drained and allow roots to grow and air to circulate. If these qualities are not present, succulents are prone to root rot, which often results in the death of the plant.
Although commercial succulent potting soil is widely available, preparing your own ensures the mix’s quality and allows experimentation. Combine ingredients in a large bowl or bucket, depending on the batch size. Measurements are generally volumetric and not by weight.
A starting basis for Alpine climate succulents would be a 30/70 mix of organic/inorganic material. The base recipe would look as follows:
- Two parts coconut coir
- One part of clean sand, preferably well sterilized
- One aspect of the perlite
- Add 2 ounces of limestone and two ounces of bonemeal for every 4 gallons of the potting mixture.
Limestone is rich in calcium and magnesium and balances the soil pH. Bone meal supplies phosphates which stimulate root growth.
One of the most prominent reasons for the failure of growing succulents from the Andes all the Alps is too little light. However, try to avoid drastic light changes, and Succulents will stretch if they do not have enough light to reach the light.
Jungle Climate Succulents
Jungle cacti include species in genera:
- Hatiora (Easter Cactus)
- Schlumbergera (Chrismas Cactus)
- Selenicereus and perhaps a few others.
Most Jungle cacti are either lithophytic or epiphytic, which means they grow on rocks or in trees. This plant draws nutrients from the air or dead leaves and other debris accumulated in nooks and crannies. It’s worth noting that there aren’t any parasitic cacti, and those that grow in trees do so for support but do not deplete the host’s nutrients. We’ll want our soil to mirror these natural circumstances for the best results.
Here’s a good mix with the essential ingredients for Jungle climate cacti. Remember, this is merely a suggested starting point. The vital needs are acidity, some forest material, and good drainage.
- 30 percent coconut coir
- 15 percent forest material – Fir bark (also called Orchard bark)
- 15 forest material – Oak Leaf Mold – for acidity
- 20 percent pumice
- 20 percent decomposed granite
Remember that the orchid bark will eventually decompose into the soil. The result will be vibrant soil that may not be as effective at keeping the roots healthy as it should be. It’s not wrong to re-pot these plants with new ground every two or three years.
After your plant has completed blooming, this is the perfect time to do it, and it will be ready to start developing again. You might also add bone meal or kelp pellets to the new mix as a fertilizer.
The ability to keep water from rotting the roots depends on well-drained soil. However, watering once a week is a good rule of thumb with suitable soil, though exceptions. During long periods of hot, dry weather, you may need to do it twice a week.
On the other hand, when it’s cool and rainy, you might only need to water every two weeks. Watering requirements for indoor plants should be more consistent. Due to the dryer air produced by the heater, folks who live in colder climates may discover that they need to water their indoor Jungle Cactus more in the winter than in the summer.
These plants resemble the ‘Christmas’ cactus in appearance and lack genuine spines. If this is the variety you have, they want a little more water, so water frequently over the spring and summer to keep the potting mixture moist.
Because these creatures are from humid jungles, misting them often, even daily, keeps them happy. Just check with your finger the first half an inch. If it’s dry, water your plant. If it’s still damp, wait a day or two. Watch out for using moisture meters between plants and cross-contaminating pathogens.
Jungle Cacti can withstand a wide range of lighting conditions. However, rather than just surviving, we’ll assume that the goal is for plants to thrive. Plants require a certain amount and intensity of light to succeed, and the whole morning light followed by afternoon shade is optimal for Jungle Cacti. Your plants will flourish as a result of this.
Other conditions may be:
- Morning shade/full afternoon sun
- Full shade
- Full sun
Your plants will often take on a yellowish color and may develop spots if they are in the shade in the morning and full sun in the afternoon.
These effects will be significantly more noticeable in direct sunlight. There are exceptions, like most things in nature, and certain plants enjoy and flourish in full sun.
The plants will appear dark green and healthy in complete darkness, but their stems will be stretched long and thin to get more light.
A plant may proliferate and produce numerous show-quality stems in perfect conditions, but it will not flower. In this case, exposing the plant to more prolonged and intense sunshine will cause it to blossom.
Can You Add Bokashi to the Mix
Bokashi is very high in organic matter and can prevent air movement and increase water retention. Although Bokashi is perfect for composting kitchen waste, It is not an ideal ingredient for cactus compost.
FAQs on Maximize Your Cactus Growth with the Right Compost Mix
Is cactus compost made from cacti?
Cacti can be part of a composting process. Generally, however, cactus compost refers to the growth medium for succulents in general and cacti in particular, and I suppose a better term would be cactus growth media.
Why make your own when commercial Cactus Composts are available?
Making your cactus compost enables you to try different combinations with control over all the elements that can contribute to your success and the plant’s well-being. Minor adjustments make a big difference.
How often should I water my cactus plant?
Watering can be done every fortnight during the winter months when succulents go dormant. In the growing season, you should keep the soil slightly moist, and during warm seasons, you should check the humidity of the soil regularly.
What is the essential feature of Cactus Compost?
Sufficient drainage balanced with nutrition. Preventing your cactus or succulent roots from standing in wet soil for extended times is vital. Some succulents also require support to remain anchored.
Peat moss is acidic; may I use that instead of oak leaf mold?
Growers generally advise against using peat moss as a growth medium for succulents, including cacti. Peat moss is hydrophobic in that it repels water when dry, and Peat moss prevents the effective draining of a pot for cacti.
Conclusion on the Best Compost To Use When Growing Cacti
Growing succulents, including cacti, is very rewarding. Every plant is unique, and every species has its demands. Once planted in suitable soil and in the right lighting environment, they continue giving year after year.
The effort to get the cactus compost mix right is worth every investment of money and time.
I trust you enjoyed this article and that it shed some light on general succulents and cacti. Mix your cactus compost and see what all the fuss is about.
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