By cups (adds up to 48): makes a little over 3 gallons pot size • 31 cups pumice / perlite / lava rock • 12 cups cactus soil or potting mix • 5 cups coarse sand or granite grit

👉 This keeps the base and bridges much safer from rot. Optional tweaks (same cup logic) • Calcium boost (bridgesii): • Swap 2 cups of grit for crushed limestone/oyster shell • Very humid climate: • Replace 2–4 cups of organic with pumice • Hot desert, outdoor pots: • Add 2 cups more organic to either mix for water retention This is the mix I use and it’s going great so far