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.
3. Plant the Aloe vera in well draining soil. Aloe vera plants are adapted for survival in dry conditions, and may rot if planted in soil that collects standing water. Use a cactus potting mix, or create your own mix using equal parts soil, sand, and gravel.