Perlite is a lightweight granular material that is white in color and is used in gardening to improve soil structure by providing drainage and aeration. It is a mined volcanic rock that is mixed into many industrial building products for stability, such as masonry construction, loose-fill insulation, cement, and plaster. It is also used as filter media for swimming pool filters, and as a filter aid for beverages and for wastewater. Some of the main uses of perlite in gardening include:

• Improving water retention: Perlite can aid water retention in compost, which can help improve the chances of cuttings taking root.
• Improving drainage: Perlites expanded nature makes it extremely porous, so it can absorb water, but it also improves drainage, so it is ideal to mix into compost to ensure water drains freely.
• Creating a free-draining potting compost: Perlite is excellent for creating a free-draining potting compost for plants that need good drainage, such as cacti and succulents. It can also help create an airy compost for seedlings.
• Mixing with vermiculite: Perlite and vermiculite can be used together, mixing a little perlite into a seed sowing mix will ensure plenty of oxygen gets to the roots, while a topping of vermiculite will lock the moisture in.
• Sterilizing: Perlite is an inert, sterile, neutral, ultra-lightweight aggregate with a very high air and water-holding capacity. To sterilize perlite for re-use, steam, flame-gun, or treat with any proprietary chemical sterilizer.

Perlite is dusty, so it is important to take care to avoid inhaling the dust. It is recommended to dampen it with water before using it. If using a whole bag of perlite in one go, pour a couple of liters of water into the bag, seal the top and shake it, then let it soak for a quarter of an hour before using. The quantity of perlite needed depends on the kind of plant youre growing in that soil. For example, for succulents, equal amounts of perlite and soil are mixed together.