About 5 years ago, Sheridan Cleland of MyPDFscripts wrote the below article on his blog. Soon after, the site disappeared. I wanted to keep the memory alive, because these practices by the studios have not changed. They have only become worse.
Cacti are one of my favorite types of plants to grow inside all year and outside in summer. Unfortunately, the ambient air tends to stay moist during most seasons, a condition which makes cacti unhappy. Cactus potting soil can enhance drainage, increase evaporation and provide the dry conditions that cacti favor.
Soil should be well-drained (a cactus mix works well) and the pot should have enough room for the plant, specifically its root ball, to grow. When re-potting, choose a container that's wider than the previous, not deeper, and with extra room equivalent to 3 to 5 times the size of the current root ball.