Quality criteria – Perlite

Perlite – substrate additive, soil improver, additive in substrates for green roofs

The raw material for perlite production is volcanic silicate rock that cooled down rapidly in sea water after the eruption of underwater volcanos. The Greek island of Milos and Hungary have the most important reserves of perlite in Europe.

The material is crushed, sifted to a defined particle size and heated to approximately 1,000 °C. At this temperature, the water trapped in the perlite vaporises, expanding the molten glass to 20 times its original size. This expansion produces a light-weight neutral material with closed nuclear pores, open peripheral pores and very good water holding capacity.

Advantages of perlite:

  • light, purely mineral material
  • chemically neutral, incombustible and frost-resistant
  • stable structure, reduces substrate subsidence
  • very good water holding properties
  • free of soluble salts
  • pH neutral
  • facilitates substrate remoistening
  • improves substrate aeration
  • free of germs and fungal spores

Perlite is used as a substrate additive in horticulture, as a soil improver in plant production and as an additive in substrates for green roofs.