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.
Pot plants correctly. The plant container type and size, and the potting soil you use have a lot to do with correct watering. 1  Use a lightweight potting medium instead of a garden soil for indoor plants.  Use special potting mixes for plants like orchids and cacti. Research your plants and use the right planting medium.