Vermiculite vs Perlite: What’s the Difference

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Vermiculite vs Perlite: Both can be added to potting mixes but what is the difference between vermiculite and perlite?

What is Vermiculite

Vermiculite is a naturally occurring mineral, aluminium iron silicate which is heated to very high temperature to produce a lightweight material with a large surface area. Resembling flakes, the sand-coloured particles act by helping to retain moisture and regulating temperature during germination.

What is Vermiculite Best Used For

Vermiculite can be used in potting mixes and seed raising mixes and is ideal for use when starting seeds in particular very small seeds. After sowing the seeds, spread a fine layer of vermiculite over the seed raising mix and water it in to keep the seeds from drying out while germinating.

Vermiculite can also be used for making seed raising mix by combining it with peat moss or coir and propagating sand. For a  a soil-less seed raising medium, combine it with perlite and peat moss or coir.

What is Perlite

Perlite is a natural and neutral volcanic rock which has been treated to a very high temperature to produce a lightweight, white, porous material with a large surface area not unlike Styrofoam balls. When mixed with soil, it forms spaces which improve aeration and enable water to move freely.

What is Perlite Best Used For

Perlite is used to provide aeration and facilitate drainage while maintaining good water retention. It helps improve compacted soil such as clay soil and reduce the chance of root rot. Use perlite where drainage is very important such as with Australian native plants, succulents and cacti, saffron and plants that don’t like being waterlogged.

Perlite can also be used to create a potting mix by combining it with coconut coir.

Vermiculite vs Perlite

In short, use vermiculite when starting seeds to help with moisture retention. Use perlite in potting mix to improve aeration and drainage.