Vermiculite
Make
Mined mineral is heated until trapped water pops the layers open, which also sterilizes it
Hold
Wide layers store water and give a large surface for nutrient buffering
Air
It starts porous, then slowly collapses as layers separate, so it is a poor solo medium in big pots
pH
Usually near neutral, though natural batches can run from about 6 to 9
Uses
Fine grade for seeds and cuttings. Coarser grade in pots up to about 6 inches, or blended into mix and hydro
Feed
It holds nutrients but does not supply a full diet. You still fertilize
Perlite
Make
Volcanic glass is heated until it foams into sterile, inert white granules with a neutral pH
Structure
Closed cells and surface craters hold a film of solution plus air. Pieces stay stable for years
Grade
Fine particles hold more water. Pea-size pieces keep large pots open
Seed start
Fine perlite stays evenly moist, drains excess, and clings to roots at transplant
Hydro
Works in wick, reservoir, drip, and constant-flow setups. In flood tables the granules can shift, so stake plants
Reuse
Rinse, remove old roots, and sterilize. It does not collapse the way peat or vermiculite can
Peat moss
Hold
Sphagnum peat can take 15 to 20 times its weight in water and buffers well
Acid
Raw peat is very acidic. Lime it, then test. Bagged mixes are often pre-adjusted
Empty
Unenriched peat has no plant diet. Feed from day one
Tension
As peat dries it grips remaining water harder, so a 'moist' pot can still starve roots
Life
Microbes eat the carbon and the volume shrinks. Fine for a few months, weaker for long-term plants
Long crop
For plants kept five months or more, prefer bark or coir over a peat-heavy mix