Here are some San Pedro that I rooted from 8" cuttings then they growing new tops. Plants were ok in this location until hot weather came. When it was 100 degrees and full sun all day plants turned yellow from too much sun. The plants did not like this soil either, it was potting soil mixed with sand. San Pedro likes a very stable moisture in the soil, not too dry, not too wet, no fluctuation in moisture, no flower pots. I moved the plants to a location that was morning sun from about 9am to 11:45am then full shade until dark and they did very well. Plants were 3ft to 5ft tall in about 1 year. I had about 30 plants that grew about 50 tops. Each 8" long cutting grew 1 top or 2 tops, if I planted the cutting on its side then they would grow 3 to 4 new plants sometimes 5 plants per cutting. Crazy thing about all cactus you can plant cuttings upside down they still grow.