I grow outside in sunny, humid central Florida where three day rains in winter are common enough to make cactus and succulent growing difficult. As you might guess, a dormant plant in a soggy mix is a recipe for disaster. The mix I use for most succulents is 20% finished compost, 20% coconut coir and 60% perlite (pumice is difficult to find here and too expensive for the volume of plants). I add a balanced time release with minors and top dress twice annually between re-potting. Because perlite migrates I top dress plants with crushed granite from a terrazzo installer. I used to use chicken grit until I found the terrazzo was less expensive. This mix works well for most other plants as well as its only drawback is the extra time I spend watering due to how fast it drains. (I actually like watering because it makes me look at each plant which helps with early detection of cultural issues) For cactus and other particularly dry growers I increase the perlite to as much as 80%.
