Perlite is a volcanic rock of the family of amorphous silica; its color ranging between white and gray. It comes in granules of different sizes and densities:

Fine perlite (0-2 mm);
Medium perlite (1-3 mm);
Horticultural perlite (2-5 mm)

Perlite Characteristics


Main properties of perlite:

Expands when heated:

Crushed perlite has the property of expanding when heated at varying temperatures between 900o to 1100o C. Its volume may increase four- to twenty-fold.

Porous texture:

Surface pores or cavities develop on perlite particles during dilation. These pores trap moisture on which plant roots thrive. Perlite particles are irregular in shape and leave air passages in the soil at the base of plant cultures, for optimal aeration.

Liquid retention:

Perlite’s porous texture retains moisture and fertilizers. With appropriate granule size, perlite provides optimal irrigation as well as perfect drainage for all your horticultural projects.

Air circulation:

Because of their irregular shape, perlite particles provide aeration in growing mixes and substrates, and in many industrial applications.

Low density – cannot be compacted:

Since heated perlite increases in volume while keeping the same mass, expanded perlite has a very low density which, combined with its other characteristics (neutral pH and porous texture), makes it an ideal filling material which cannot be further compacted.

Chemically neutral:

Perlite is an odorless, non-flammable, and non-explosive chemical; an inorganic component which does not deteriorate. Other benefits of horticultural perlite are its neutral pH (6.5 to 7.5) and the fact that it is sterile and weed-free. These reasons explain its popularity for various applications from window boxes to filtration in pharmaceutical and food industries.

Low conductivity – insulation, fireproofing and soundproofing:

Perlite’s low conductivity makes it an ideal refractory material in bricks or tiles or as insulating material in pipes.

For more information on perlite

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