The best cactus soil is roughly 90 percent mineral and 10 percent organic. A DIY cactus soil mix recipe (pumice, lava rock, zeolite, granite, limestone, worm castings) with per-genus ratios for Lophophora, Ariocarpus, Astrophytum and Copiapoa, plus the squeeze test.
Miracle-Gro Cactus, Palm and Citrus soil kills rare cacti because the bag is 70-80% peat moss, perlite, and bark fines. Here is the autopsy of what is in the bag, why those ingredients fail, and the five-mineral collector mix that replaces it.
A diagnostic flowchart for the six visible failure modes that kill cacti in cultivation, the rare-genus rot vulnerabilities most generic guides miss, and a step-by-step recovery protocol for plants that can still be saved.
