GandB Perlite

G&B Organics Perlite is a single-ingredient amendment from the G&B Simples line, made from expanded volcanic glass. Perlite starts as obsidian-like volcanic rock; when heated to very high temperatures it pops and expands into the white, lightweight, porous granules found in most quality potting mixes. The resulting material is sterile, has a neutral pH, does not decompose, and creates persistent air pockets in soil or potting medium.

Add it to dense potting soils or homemade container mixes to improve drainage and aeration around roots. A common blend is one part perlite to three parts potting mix, though you can go higher for plants that need especially fast drainage, like succulents, orchids, or alpine perennials. It is also useful for rooting cuttings in a lightweight, well-drained medium. Because perlite holds some moisture in its pores while allowing excess water to drain freely, it hits a useful balance for most container work.

Perlite is a staple amendment in any nursery, and the G&B version is clean and consistent, available through independent garden centers in the Western US. Wear a dust mask when measuring out dry perlite in quantity, as the fine particles can irritate the airways.