If you want to enjoy your prickly ornamental plant for a long time, choosing the right cactus soil is indispensable. The plant family of the so-called "Cactaceae" includes about 1800 different species of cacti.
Only a few of them can tolerate a lot of moisture and high nutrient levels. The vegetation on our planet has adapted to the most diverse conditions over millions of years. Some plants have learned to survive even in extremely dry and nutrient-poor conditions. These include, above all, cacti and succulents.
In our comprehensive cactus soil test 2021 we explain to you exactly what is important when buying the right substrate and present our favourites.
- 1 Weekly newsletter with the best personal finance tips
- 2 Summary
- 3 The Best Cactus Soil: Our Choices
- 4 Buying and evaluation criteria for cacti soil
- 5 Guide: Questions you should ask yourself before buying cacti soil
- 6 Conclusion
- Cactus soil should have a loose structure so that water can drain off well and no waterlogging can form. Very loamy substrates such as conventional potting soil are not recommended. The pH value should be between 5.0 and 7.0.
- Mineral substances have the ability to store water and nutrients over a longer period of time and to continuously release them to your plant. They also provide ideal drainage properties and should be included in every cactus and succulent substrate.
- Ready-made substrate mixtures are available in various sizes. You can find just the right amount for your project in many online shops. Store your excess soil in a dry and cool place.
The Best Cactus Soil: Our Choices
Buying and evaluation criteria for cacti soil
In this section we look at the most important factors you should consider when buying cacti soil. In order for your cactus to thrive, you should provide the right conditions. This starts with choosing the right substrate. In summary, these are the following points:
In this section we explain in detail how the individual factors influence your purchase decision.
A soil with a loose and water-permeable consistency is recommended for cacti. This is important because waterlogging leads to rotting and your cactus will eventually die.
Very loamy and humusy substrates are therefore not recommended. This also includes potting soil and universal soil. These do not really store water, but merely "retain" the water in the pot for a few days.
Special substrates for cacti and succulents have a suitable consistency. In addition to the humus content, a mix of mineral elements such as quartz sand or perlite provides the necessary drainage.
Compared to other plant species, cacti manage with relatively small amounts of nutrients. Most cacti soils with an organic content contain a so-called starter fertiliser, which provides your plant with nutrients during the first few weeks.
The most important nutrients for plants are nitrogen (nitrogenium), phosphorus and potassium. These are contained in every starter fertiliser. In the following table we show you the function of the individual elements in the plant world:
|Nitrogen (N)||growth, important component of photosynthesis|
|Phosphorus (P)||root development, cell division, formation of defence substances|
|Potassium (K)||formation of supporting tissue, improved water circulation, activation of plant enzymes|
The ratio of the composition of these three nutrients is also called the NPK value. You will often find this on the back of the packaging of your cactus soil and also on every fertiliser. For cacti, an NPK ratio of 1:1:1 is recommended.
For every part of nitrogen there is one part of phosphorus and one part of potassium. A higher phosphorus or potassium value is no problem and is used by many manufacturers. However, the proportion of nitrogen should not be higher.
If you are looking at the criteria for a suitable substrate for your plant, sooner or later you will come across the pH value. It has a great influence on the absorption of nutrients.
Even if there are enough nutrients in the soil, your cactus will not be able to absorb and process them if the pH-value is wrong. The pH value indicates how acidic or alkaline your substrate is. The scale ranges from 1 to 14, with 7 being the neutral middle.
However, plant growth is only possible between a pH value of 4 and 8:
|9||No plant growth possible|
|6||Suitable for most plants|
|3||No plant growth possible|
Cacti are also relatively robust when it comes to pH. Most species feel comfortable between a value of 5.0 and 7.0. They prefer a slightly acidic to neutral soil. So avoid alkaline substrates when growing your cactus.
Another purchase criterion is the quantity. The size of your pot will tell you approximately how much you need. If you have no idea how much capacity your pot has, then you can calculate this relatively easily. Simply measure your pot and enter the values into an online soil volume calculator.
So if you have to plant or repot a lot of cacti, it is worth buying a large pack. However, it is better not to have too large a supply of soil. Over time, substrates lose their nutrient content. Incorrect storage with too much humidity can even cause your cacti soil to become mouldy.
Guide: Questions you should ask yourself before buying cacti soil
In this section we deal with all the uncertainties that can arise around the subject of cacti soil. We have selected the most frequently asked questions for you and try to answer them briefly and concisely. Here you will find all the necessary information that will contribute to the well-being of your prickly friend.
What is special about cactus soil and what advantages does it offer?
The growing conditions should be as close as possible to the natural habitat of the cactus species.
Cacti belong to the succulent family. They are characterised by their ability to store water and nutrients excellently. Depending on the species, this happens in their stem, leaves or roots. A high-quality substrate takes these characteristics of cacti into account.
The structure should be loose and slightly crumbly so that water can drain off well and enough oxygen reaches the roots. The soil should store water and nutrients only in moderation.
Waterlogging or excessive amounts of nutrients will damage the plant. A special soil for cacti is therefore quite sensible.
What types of cactus soil are there?
Cacti from very dry regions prefer an almost purely mineral substrate, whereas cacti species from humid tropical latitudes tolerate and also require a high organic content. Here we explain exactly what the difference is between the two types.
Mineral cactus soil
Pure mineral cacti soil usually consists of a combination of pumice, lava, perlite, vermiculite and zeolite. These are rocks and minerals of volcanic origin. These substances store water and nutrients, but release them only slowly.
A purely mineral composition will never compact and will always ensure sufficient oxygen circulation in the root area. Thus, this soil also offers excellent drainage properties and is ideally suited for cacti species from drought regions.
Organic Mineral Cactus Soil
Most industrially produced cacti substrates consist of an already decomposed organic and a mineral part in a ratio of 1:1. The organic part is also called humus. It is very rich in nutrients and, together with water, quickly releases them to the plant.
Humus soil contains a large number of microorganisms that ensure a sustainably healthy environment in your substrate. However, care should be taken when watering predominantly humic soils: Overwatering quickly leads to waterlogging and the roots of your cactus can start to mould.
An organic-mineral mixture is suitable for most cacti. However, you should inform yourself about your cactus species in order to know which of the two substrate types your plant needs.
For whom / what is cactus soil suitable?
You should also replace your cactus soil every two to three years. This is because the minerals in the substrates accumulate salt through watering and fertilising. Too much salt in the soil is detrimental to the well-being of your plant.
Owners of other types of succulents can also use cactus soil. For example, a cactus substrate is excellent for aloe. This plant genus originates from the dry regions of Africa and has similar characteristics to cacti.
How much does cactus soil cost?
|2.5 litre pack||circa 3 Euro|
|5 litre pack||circa 5 Euro|
|10 litre pack||circa 10 Euro|
|25 litre pack||circa 20 Euro|
It is often worth buying a larger package directly, as potting soil, like almost all products, is offered cheaper in quantity. It should be stored in a cool and dry place, as nutrients are broken down more quickly at high temperatures.
After about six months, a loss of quality is unfortunately unavoidable and the soil should be re-fertilised if necessary.
What alternatives are there to cactus soil?
- 50 % universal potting soil
- 25 % quartz sand (not play sand)
- 15 % perlite
- 15 % pumice
Depending on the needs of your plant, you can adjust the proportion of organic (potting soil) and mineral components. If your cactus prefers a dry and nutrient-poor soil, simply reduce the amount of potting soil.
|Ready-to-use mixture||Suitable for most species, little effort, available in small quantities||Fixed set of ingredients|
|Mix yourself||Individual composition possible, Suitable for experts, pH value can be adjusted||Usually only large quantities of the individual ingredients available, Time-consuming|
Keep in mind, however, that you can usually only buy the individual ingredients in large quantities at the DIY store. For a normal consumer, the DIY method offers no advantage from a price point of view.
Now you should know all the important information about cactus soil and how you can make your plant happy. With the right composition of the substrate, your cactus can easily absorb and process water and the necessary nutrients.
With these tips you will hopefully be able to enjoy your cactus for a long time even without a green thumb. Your other succulents will also benefit from the specially optimised substrate and thank you for it!
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