The best way to cultivate any plant, and especially those that come from places with unique climates, is to simulate their environment in your home.
Cacti come from arid desert landscapes where the soil is very dry.
Cactus compost is a combination of components in soil that cacti can thrive in. It works very well in imitating desert soil, giving cacti its ideal living conditions.
Cactus compost is usually a mix of peat moss, soil and grit. Planting your cacti in cactus compost will make it grow better than using regular garden soil.
What kind of soil does a cactus like?
Most cacti species originated from Africa, parts of Europe and both North and South America. Cacti have stems that are great at retaining water and moisture, which is how they are able to survive harsh desert conditions.
The sandy soil typical for deserts plus the dry desert conditions dry out the ground almost immediately after rain. Because of this, cacti never have to sit in water for extended periods of time.
Cactus soil must have good drainage, must not be too compact and must have great air circulation. All three factors need to be present, as too moist soil can lead to root rot, pests and fungal problems.
Root rot attacks the cacti’s water absorption main channel and will spread towards where the water is stored. The plant will eventually shrivel and become weak until it dies.
What is good cactus soil?
Whether the cactus is kept indoors or outdoors, the soil it is planted on will determine the amount of water retained. The most important factor that any cactus potting mix should have is that it drains well. It has to be porous enough for water to seep through quickly giving the soil a chance to dry out completely in a short amount of time.
The best soil for cacti can be considered poor soil for other houseplants, especially those that originated from the jungle. Cactus soil has more inorganic elements compared to regular soil and has only about 25-50% of organic matter.
Inorganic material is important for cactus soil because it is what keeps the soil porous, allows it to drain well, and makes sure that air circulates through the soil. The most widely used inorganic components for cactus soil are perlite and pumice. You can also use gravel or grit.
Organic material is also added to cactus soil because it helps the cactus absorb and hold more water and nutrients. Examples of widely used organic components or cactus soil are mulch, coir, and peat.
Can I use regular garden soil for cacti?
Regular garden soil can have too much organic matter and may retain too much water for cacti. They also have too much added nutrients, some of which cacti may not agree with. You can use regular garden soil but you have to mix it together with an inorganic material like perlite or pumice for better drainage and less water retention in the soil.
What is cactus compost?
Cactus compost is a mix of both organic and inorganic materials to form a soil that is most ideal for cacti to grow on. It has superior drainage and tends to dry out quicker than normal garden soil. The cacti will quickly absorb the water it can sustain and the excess water has to dry out or drain to prevent root rot and fungal problems.
You can buy commercially sold cactus soil mixes, but once the peat has dried out, the soil may have a difficult time reabsorbing water. You may be better off customizing your own cactus compost so you can design the mixture specifically for the type of cactus you will be planting.
How can I make cactus compost?
Gather the following components to mix your own cactus compost:
1. Regular garden soil
Any kind of garden soil you have on hand is fine to use. It will work especially well if your soil is light and porous. This will be the base of your cactus compost. Heavy garden soil usually means that it will retain a lot of moisture so steer clear of that for your cacti. Keep in mind, we need well-draining soil.
Cacti come from the desert where sand is abundant, so it makes sense for there to be sand in cactus compost. Adding this to soil will make it porous. You can use any sand, but coarse sand is ideal. Do not use beach or sandbox sand because those are too fine. You can use turface or poultry grit as an alternative.
3. Pumice or perlite
Perlite is an organic soil additive that is lightweight and resembles styrofoam. It helps with keeping the soil from getting compacted and to promote plant aeration. It also helps with the water drainage. Pumice does pretty much the same thing.
The pH level of soil can affect the plant in it. One way to lower the pH of your soil is to add a little peat to the mixture.
5. Lava rocks/ gravel
When added to the cactus compost recipe, they will help keep the soil airy and loose.
Before you start combing the components, gather a measuring cup, a bucket, a trowel and gardening gloves.
Take three parts regular soil, three parts sand, turface, grit, or gravel and two parts perlite or pumice.
Once you have all the components measured, you can move on to the next stage, which is mixing it all together.
Moisten the garden soil first so dust does not rise up while you are mixing. Start adding in the sand and mix well. Using your hands will loosen clumps and combine them better.
Take the perlite or pumice and add to the mixture. Mix well.
If you have a pH measuring meter, test a small sample of the soil. If the pH is below or beyond the normal values, add a small amount of peat. Stir the mixture well before measuring the pH again.
Making your own cactus compost is better for your cacti and can also save you a lot of money. You can customize and personalize the soil for the kind of cactus you wish to plant. The most important factor to keep in mind when creating cactus compost is that it has to be well-draining, and properly aerated.
Image: istockphoto.com / Dejan_Dundjerski