Purchasing bagged cacti mix is easy and convenient. However, some people find it more economical to create their own potting mix for the specific plants they grow. By watching how your plants respond you can make adjustments to be sure your mix drains well while providing your succulents with the environment they need.
One simple mix is semi-homemade. A commercial mix that seems a bit heavy can be supplemented with extra perlite or pumice in a one to one ratio. Perlite and pumice both help drainage. Perlite usually costs less, but it can work its way to the top of the soil because it is so lightweight. Pumice stays blended better.
Succulent potting mix typically has three major ingredients. One is something organic. This may be peat, coir, or fine pine bark. The bark that is used on pathways is too coarse. Pet stores sometimes sell pine bark for reptile cages that is made of small pieces. Peat is thought by some to increase the likelihood of mealybugs because it retains moisture.
The second ingredient is some type of grit. This has to be something that doesn't form clumps. Perlite, pumice and grit used to feed chickens are good candidates. Chicken grit can be purchased at feed stores. Vermiculite can also be used to keep the soil “fluffy” because it is lightweight like perlite. Some people prefer it because its tan color blends in with the soil and it has a bit of sparkle to it.
The third item is something to absorb moisture but will not break down. Some products that do that are Turface, Drystall, Napa Floor Dry and calcinated diatomaceous earth. If you are using diatomaceous earth in the form of kitty litter, be sure that it is not the type that gets mushy. You can test for this by putting some in a jar with water and observing what happens.
These three ingredients – the organic material, grit, and moisture absorbent can be mixed in equal parts by volume. Then horticultural grade sand can be added for cacti.
A fast draining potting soil is essential to the health of your succulents. How you pot them is also important. Be sure your container has a drain hole and do not put a layer of gravel in the bottom of the container. This only creates a perched water table which results in soggy roots. A pot shard or piece of screen over the drain hole will prevent the soil from escaping.
Although many succulents do not require fertilizer, a diluted solution of a balanced fertilizer during the growing season can give them what they would get in a more natural environment.