A volcanic glass expanded by heat into lightweight white particles. Used in potting mixes to improve drainage and aeration. Sterile, pH-neutral, and very long-lasting. Essential in seed-raising mixes and succulent/cactus blends.
Perlite is made from obsidian that's heated to extreme temperatures, causing moisture inside to expand rapidly and create tiny air pockets. This makes it incredibly light and useful for improving soil structure in Australian gardens, particularly in areas with heavy clay or poor drainage.
In Australia, perlite is widely available at Bunnings and garden centres across all states. It's particularly valuable for potted plants during hot summers (December-February) when moisture retention can cause root rot in poorly draining soils. The material doesn't break down over time, making it a long-term soil amendment investment.
When amending garden beds or creating potting mixes, combine perlite with other materials like coir or compost. A typical mix might be 30-40% perlite, 30-40% coir, and 20-30% compost for most Australian gardens. It's especially beneficial in tropical and subtropical zones (9-11) where heavy rainfall can waterlog roots, and in arid zones (9-12) where it helps retain moisture while preventing compaction.
Perlite works well for indoor plants, succulent gardens, and seed-raising. Always wear a dust mask when handling dry perlite, as the fine particles can irritate lungs. Moisten it slightly before mixing to minimise dust.