What would the best soil and care for a san Pedro cactus?

san Pedro being a cactus should have a fast draining soil, i usually mix half commercial potting mix with sand and maybe some diatomaceous earth or pumice to increase the drainage if your ambitious enough but the half sand and half potting mix should be fine, during the growing season san Pedro being a faster growing cactus can be watered quite a bit of water maybe every 5-7 days if its hot enough and has properly draining soil. during the winter i don't ever water my bigger cacti and i might water my smaller ones maybe once during the winter. as long as the soil has completely dried out for a few days it can be watered again the key is just not to let it stay in moist soil for too long. ive heard of people even putting shredded tires into their mix to increase drainage. a simply test would be take a handful of your soil mix and squeeze it, it should fall apart if it sticks together try putting more sand in.