Perlite
/ˈpɝlaɪt/
Definition
Perlite is a lightweight, porous material made by heating volcanic glass until it expands into white granules. In horticulture, it is used as a growing-medium ingredient rather than a fertilizer or soil. Its main defining traits are high air space, low weight, and low water retention compared with vermiculite, which helps roots get oxygen and improves drainage in potting mixes, seed-starting media, and some hydroponic systems.
Use in Gardening
- Root-zone aeration: In potting mixes, perlite creates air spaces around roots. Better oxygen access supports root respiration and can reduce problems linked to compacted, soggy media.
- Drainage balance: It helps excess water move through a container while still holding a small amount of moisture on its surface. That balance is useful for many houseplants that dislike waterlogged roots.
- Propagation support: Cuttings and seedlings are often started in mixes containing perlite because the material stays open and light. This can encourage new roots while lowering the risk of rot in overly dense media.
- Mixing with other ingredients: Perlite is commonly blended with peat, coco coir, bark, or compost to adjust texture rather than fertility. It contributes structure, but it does not provide meaningful plant nutrients on its own.
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