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Cacti are some of the best plants for beginner gardeners. They don’t require a lot of care and thrive easily, even if you forget about them for a few days or even weeks. However, cacti only thrive in low-maintenance conditions if you plant them in the right soil or compost.
While ericaceous compost is great for many plants, it is not the best for cacti. Cacti grow well in soils of various pH levels and don’t need the acidity that ericaceous compost brings. They also do not thrive when exposed to organic matter, which ericaceous compost has in droves.
When it comes to repotting your cactus plants, put the ericaceous compost away and reach for something more suitable, such as specially mixed cactus soil. Here is your guide to optimum planting conditions for cacti and why you should go sparingly on the ericaceous compost.
What Is Ericaceous Compost?
Understanding what ericaceous compost actually is can help you understand why it is not suitable for cacti.
This compost is a combination of organic matter such as leaves, pine needles, loam-based soil, and more that is highly acidic. It is the best compost for acid-loving plants such as rhododendrons and heathers.
The other distinguishing quality of ericaceous compost is its high organic matter content. Ericaceous compost, whether you make it at home or buy it from the store, is mostly organic matter, which ensures a nutrient-rich, moisture-retaining soil that is ideal for most plants but not succulents.
What Are the Best Conditions for Cacti?
Cacti are a famously low-maintenance plant that are recommended for forgetful gardeners. However, the low-maintenance reputation is slightly misleading. While cacti don’t need a lot of water, they still require plenty of care to ensure their unique growing conditions.
Cacti are naturally desert plants, which means they thrive best in dry conditions. Their fluctuating root system is tailored to survive in a desert environment when rains are rare and the soil dries out quickly.
That means that if you overwater the cactus or put it in soil that retains too much moisture, the roots will start rotting, and the plant might die.
Cacti also don’t do well in soils that contain lots of organic matter. Organic matter usually holds on to water, which is great for plants that need plenty of water but not for plants such as cacti that need excellent drainage.
Why Is Ericaceous Compost Not Good for Cacti?
Ericaceous compost is not recommended for cacti for a few reasons. This compost has a high concentration of organic material, which is why it is so appealing when planting flowers that require lots of nutrients. However, this organic material impedes the soil from draining properly and will cause the cacti’s roots to rot.
Another reason why ericaceous compost is not recommended for cacti is its acidity levels. The purpose of ericaceous compost is to bring down the pH of the soil, but very few cacti varieties actually enjoy acidic soil.
Passionate gardeners still debate whether it is best to grow cacti in neutral, slightly acidic, or slightly alkaline conditions, but the consensus is that the very acidic conditions created by ericaceous compost are not the best for cacti.
Can You Ever Use Ericaceous Compost with Cacti?
There are a few situations when you can actually use ericaceous compost with cacti.
While you can’t directly plant cacti into ericaceous compost as you would another plant, you can use ericaceous compost to make a cactus soil mix. Gardeners recommend creating a mix of sand, inorganic material, and some organic material for your cacti.
You can use little bits of ericaceous compost mixed in with sand, pumice, and other well-drained inorganic materials to create your potting soil.
However, only use ericaceous compost if you know the cactus variety you are planting likes acidic conditions or you have nothing else on hand. Usually, cactus potting soil requires organic material that is fast-drying, and ericaceous compost is designed to retain moisture. Add only a bit of ericaceous compost.
How Can You Make Cactus Potting Soil?
Because the growing conditions for cacti are so different from the requirements of other plants, these succulents require their own growing soil and compost. You can buy specially marked cactus potting soil at the store or make your own.
Making your own gives you more control over the contents and is a very creative process gardeners find rewarding.
Cacti do best in sandy soil that drains well, so the bulk of your cactus compost will be sand. Most experts recommend using building sand. Sandbox sand is usually too fine, and other types of sand may contain fine amounts of grass.
Then, you will need one part of inorganic material. Well-drained inorganic materials such as pumice, perlite, grit, or gravel bulk up the soil and prevent the sand from compacting down. This allows air pockets to form in the soil, which helps when root systems need to expand, water needs to collect, and excess moisture needs to drain.
Some inorganic materials, especially volcanic rocks such as pumice, contain additional nutrients that cacti need.
Finally, add one part of well-draining, fast-drying organic material. Most gardeners recommend coco coir and composted rice husks. These materials are long-fiber substances that absorb water well but don’t hold on to moisture for too long and aren’t prone to rotting.
Some people use small amounts of peat moss, but this substance retains too much moisture for most cacti, and there are concerns about its sustainability.
The exact mixture will differ depending on the species of your cactus, so check forums for advice, and try a few different mixes before deciding on the best one.
Final Thoughts
Ericaceous compost is great for many plants but not for cacti. It retains too much moisture for these desert plants to survive, and they don’t do well in highly acidic conditions either. Instead, plant your cactus in a well-draining mix of sand, inorganic matter, and fast-drying organic material that won’t rot.
Sources
- https://smartgardenguide.com/what-soil-do-cactus-need/
- https://www.cactiguide.com/forum/viewtopic.php?t=30526
- https://succulentplantcare.com/best-soil-and-fertilizer-for-cacti-and-succulents/
- https://honeyandeggs.co.uk/how-to-mix-cacti-succulent-compost
