Christmas Cactus Soil: "Arizona Cactus Potting Soil" Myth and Proper Mix

Friend wants "Arizona cactus potting soil" for Christmas cactus. No such product exists per Arizona contacts (one knew "Arizona fertilizer"). What matters: well-draining mix. Use 1:1 peat moss (or sterile soil) and perlite. Moisten to crumble. Next size pot (or +2 if rootbound). Screen over hole. Check roots—white=healthy, remove dead, loosen bound roots (nutrient starvation). Christmas cacti need more water than desert cacti—water thoroughly after 1 week, then regular schedule. No standing water. Protect from direct sun. "Arizona fertilizer" unverified—any soluble houseplant fertilizer (Schultz 10-15-10 monthly) works. Tropical jungle origin = moist, shaded, not desert treatment.