We all know cacti come from the desert. But, what if you live up North, in the tropics, or anywhere that’s not full of sun-baked sand? Is it still possible to grow a cactus? The answer is yes, but only if you have the right cactus soil.
In this article, we’ll dive into the soil needs of cacti and what you can do to help them thrive. It’s not difficult to provide exactly what your cactus plants enjoy!
What Cacti Need
Let’s consider how cactus plants have adapted to the desert. The camels of plants, they store moisture in their stems and leaves to last through long droughts. The exterior of the plants is used to being dry and warm, even underground.
Because desert soil is rarely soaked for long periods of time, cactus roots don’t respond well to constant moisture. When left sitting in water, they’ll usually rot and die.
To protect your plants from excess moisture, cacti need well-draining soil. Too wet, and the plant may suffer from root rot. The water should run through the soil quickly so that it’s left damp, but it shouldn’t be muddy in consistency. Depending on the cactus’s location, well-draining soil will usually be completely dry 5-7 days after watering.
Proper cactus potting soil isn’t only about dirt. One of the most important parts of growing succulents like cacti is drainage holes. If your cactus’s pot doesn’t have one, the water will fill up the bottom of the pot and soak the roots.
Putting gravel under the soil cannot replace a drainage hole. This will only make the water build up by creating an artificial water table.
The bottom line is, if you really want to keep your cactus healthy, you need to invest in good soil with excellent drainage. You’ll also need drainage holes in your pots.
Making Your Mix From Scratch
It’s super easy to mix your own succulent potting mix, and it can often be cheaper to do so. You just need three components: a base, course material, and supplement. With the right balance, you can mix a soil that’s perfect for your cactus.
When referring to parts here, we’re talking about the same size container for each “part”. That could be as little as a cup or as much as a cubic foot, depending on how much you plan on mixing. Just use the same size container to measure out each part.
Base
As a general rule, all potting mixes are made from a blend of peat humus, sphagnum peat moss, and occasionally long-fiber sphagnum moss. These materials hold moisture, but most importantly they drain off excess water extremely well.
You want some moisture to remain, but the extra water must easily flow out to protect your succulents!
While it’s possible to DIY your own blend, it may take a lot of fine-tuning to mirror the commercial blends and their efficacy. Peat humus – the material that makes up the very bottom layers of a peat bog – is a very expensive material.
A bag of sphagnum peat moss is much more reasonable and is usually sterilized to ensure it’s safe for your plants. Finding long-fiber sphagnum moss that’s been sterilized is also a challenge, but sometimes is available in bags as a product for bedding in reptile tanks.
The easiest option for most gardeners is to use a pre-made potting soil blend designed for African violets.
An African violet soil mix usually contains the right ratios of humus, peat moss, and long-fiber moss, plus a coarse material to provide drainage.
In addition, a pre-made mix like this has been sterilized, so it’s safe from potential pathogens that could harm the plants in your garden.
For our DIY recipe, we recommend using two parts of African violet soil mix.
Coarse Materials
Aeration is a major part of making the soil recipe ideal for a cactus. Too much soil or peat products won’t allow enough air to get to the roots.
So, we’ll add an equal amount of coarse material to the potting soil. Perlite is an excellent option because it drains well. Pumice, a coarse-grained sand, and poultry grit also can work well here.
If you’re starting with a DIY base, use more coarse material than if you’re using the African violet mix. Remember, the African violet mix already has some coarse material in it.
For our DIY recipe (using the African violet mix),we recommend 2 parts of coarse material.
A good blend is one part perlite, one part coarse sand. This breaks up the peaty goodness with a lot of gritty material, but half of it is smaller particles. Doing this provides both drainage and aeration.
Supplements
Like cooking, other ingredients can be added in and adjusted to your taste. Some gardeners prefer to work with coconut coir, which acts very similar to sphagnum peat moss. Others like to add vermicompost.
Orchid bark is another common additive for chunky aeration. It really depends on personal preference and what works for you and the plants you’re growing.
Limit your supplements to small amounts. We recommend using less than one part supplements in your potting mix.
Mix It Up!
Depending on how much you’re making, you can mix the cactus potting soil in a large bowl, bucket, or even a wheelbarrow. A scoop or hand trowel is perfect for mixing.
Combine your ingredients dry and then test out your creation. Fill a small pot with the cactus mixture and give it a drink. The water should run out the drainage hole fairly quickly while also wetting the soil. The soil shouldn’t be so wet that it’s muddy, but should be damp to the touch.
What About Fertilizer And Cactus Compost?
Fertilizer does benefit most cacti and other succulents, but only when applied at the right time. Many varieties only need it at the beginning of the growing season.
Because of this, we recommend keeping cacti compost and fertilizer out of the soil mixture initially. You can apply it to the soil later, when the time is right for your cactus.