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Is perlite and vermiculite sustainable?

For potting mixes, I have to use quantities of perlite and vermiculite. But I am concerned about their sustainability and how they are obtained.

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Both perlite and vermiculite are open mined in various countries. Perlite is what's known as volcanic 'glass', whereas vermiculite is actually a mica like mineral. Perlite is also put through a heating process to persuade it to 'pop' in order for it to be useful in potting soil as well as other applications. Both materials have a number of other uses, notably in the construction industry; this link has a separate embedded link to information on vermiculite too https://sciencing.com/perlite-5402928.html.

Ultimately, it depends precisely what you mean by sustainable; both products are mined all the time for other uses, but the heating process for perlite could be considered non environmentally friendly. In terms of horticultural use, there is a more environmentally damaging substance (when dug up) contained in many potting soils, which is peat, of which there is obviously also a finite supply. This https://www.greenschoolsalliance.org/blogs/16/428 gives a little more information on ingredients used in potting soils and their environmental sustainability.

  • The article mentioned sharp sand as the alternative to perlite and vermiculite. What are the other eco friendly alternatives to vermiculite and perlite? – Aksh Nov 16 '19 at 3:37
  • There aren't many options really - horticultural grit, sharp sand and silver sand are about it, but remember, even they are extracted from the earth and treated, even if that's only by washing. – Bamboo Nov 16 '19 at 10:36
  • There are a number of alternatives for perlite and vermiculite. Pumice and calcined clay are two that come to mind. I'm not sure if either are any more sustainable perlite or vermiculite. Sand or grit are not interchangeable options for perlite and vermiculite. They lack porosity and the ability to absorb and release moisture among other attributes. All in my opinion, of course. – Tim Nevins Nov 18 '19 at 15:15

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