In their native habitat Schlumbergera grow as either epiphytes (on trees), or lithophytes (on rocks) where their roots are exposed to the air. When grown as a container plant, they require a light and airy, well draining soil and the pot should be just large enough to snugly hold the roots and soil. Regular potting soil or cactus mix should be fine but I'd advise mixing in lots of perlite to aid in sufficient aeration and drainage. The soil should be damp throughout, never excessively wet, so be sure to allow for sufficient drying time between watering.
Christmas Cactus (Schlumbergera truncata)
