|L.O.I.(SO3, CO2, H2O) 2,0% - 6,0%||2,0%||-||6,0%|
|Bulk density||70 kg/m3(+/- 10%)|
|pH||6.5 – 8.5|
|Heating temperature||890 - 1100 O C|
Perlite for Horticulture
When perlite ore is expanded or “popped” by rapid, controlled heating, it expands up to 15 times its original volume and takes on a foam-like cellular appearance – essentially clusters of microscopic glass bubbles, creating a porous structure. This physical transformation makes expanded perlite an extremely effective aggregate for use in horticultural growing mixes – or, by itself, as a medium in hydroponic growing and as a rooting medium. (For a detailed explanation of perlite expansion, see Infosheet: Why Perlite Works).
The primary role of expanded perlite in soilless growing mixes is aeration when added to peat moss, composts, coir and other water-holding aggregates. The porous surface of expanded perlite provides room alternately for both air and water in the mixes – each needed for vigorous root growth. Different sizes of perlite are produced for this purpose, offering growers various amounts of air space after drainage. Usage rates by volume vary from 5% to 40% for potting mixes, and as high as 75% to 100% in green roofs and hydroponics applications. Perlite use is increasing in agricultural and turf grass applications to break up compacted soils and retain water in dry climates.