I just bought mescaline cactus (not seed)
They look small when do they mature and what do they need to grow? Can you suggest a source?
You need good draining soil, water once a week in the summer, every two weeks in the winter. A nice dose of cactus fertilizer once a year. And then wait five to ten years. If you have the San Pedro then water twice a week in the summer, plenty of sun, fertilize twice each year.
They grow over a foot a year. Cut the tops off some of them in your second year and root them. The next year you will have "pups" or "sprites". Pop those guys off and root them, you will soon have all the cactus you will ever want. I probably have 200 feet and I now do nothing but feed them once a year