As I like to experiment 2 of them are a cactus soil mix with a little additional pumice added in. The other 2 are cactus soil mix with some potting soil added in so this would be a heavier mix.
I have found that semps grow in anything have had them planted in just about every mix, top soil , dirt from the ground, compost, peat about the only thing that did not work to well for me was a heavy mix of sand.
