Complete guide to cactus soil

Cacti have evolved to thrive in desert regions where conditions are hot, frost-free, and predominantly dry, which is why they make ideal house plants in the UK. Because rainfall levels are extremely low and erratic in their native habitats, cacti have developed water-storing tissues in their stems, leaves, or roots. This means they must be grown in specially prepared compost, otherwise their roots and stem bases would quickly rot, and the cactus would die.

What soil do cactus need?

Soil for cactus plants needs to be porous and free draining so it doesn’t hold on to moisture. Regular potting soil or multi-purpose composts are not suitable for growing cacti and other succulent plants, because they hold moisture for a longer period of time, and this would cause cacti to rot.

What is the best soil or compost for cactus?

Cactus potting soil is specially formulated to have an open, free-draining texture, with a low proportion of organic matter, to keep fertility low. White traditional cactus soil mixes contain peat, there’s now a wide variety of peat-free cactus composts available. In appearance, cactus compost looks gritty due to the high proportion of fine grit or coarse sand it contains. It may also contain perlite, which looks rather like tiny white beads.

What is the difference between cactus and succulent soil?

Succulent plants are similar to cactus plants in that they have also developed mechanisms to cope with dry conditions, usually with fleshy, waxy coated leaves, although only cacti can cope with the harshest desert conditions, so they are even more drought-tolerant than succulents. The ready-made potting compost that is often available from garden centres or some online suppliers is often designed for both cacti and succulents, which means it may contain a higher proportion of water-holding organic matter than cacti need. This is easily solved by adding a little more material to open out and improve the drainage, such as coarse sand, grit, or perlite.

How to make your own cactus soil mix

Making your own cactus compost is straightforward to do if cactus compost isn’t available, or if you only need a small amount.

You will need:

• Low-nutrient potting compost, such as a peat-free seed compost. A loam-based John Innes no 1 type is ideal
• Coarse sand or horticultural grit. Both are available to buy – do not use sand or grit dug from the garden as the texture is unlikely to be suitable and it won’t be sterilised
• Perlite – this light, white, granular material is made from expanded volcanic glass
• A clean and dry container for mixing, such as a large bowl or a bucket
• Measuring scoop (something from the recycling such as a yoghurt pot) or a trowel

Step 1 In your mixing container, place three parts (by volume) of potting compost to two parts sand or grit

Step 2 Mix together using your hands, or a trowel, taking care to get right into the corners so all the material is thoroughly mixed

Step 3 Add one part (by volume) of perlite, dampening it slightly first to avoid creating dust, and mix again. Your cactus compost is now ready to use