Date: Thu, 24 Apr 1997 11:05:53 +1000 From: "Michael Reardon" <m-reardon@adfa.oz.au> To: cp@opus.hpl.hp.com Message-Id: <aabcdefg1630$foo@default> Subject: Re: perlite, vermiculite?
> >Niels Asger Nielsen wrote:
> >
> > I have an English dictionary but perlite and vermiculite are not
> > there. Could someone explain to me what it is. I understand that
> > it is used for making soil with good drainage. ....
>
> Perry Malouf wrote:
> Yes, perlite and vermiculite are added to growing media in order to
> improve drainage and to increase porosity.
>
> This listserver had a good discussion of what these are,
> exactly; perhaps it was last year sometime. The archives
> would contain the complete information.
>
> I'll summarize my understanding. Perlite consists of small white
> granules derived from volcanic ash. The granules float in water,
> and seem to be inert. They don't rot or break down. Some people
> have reported that perlite can contain traces of fluorides or other
> salts which might not be good for plants. I've used it in my
> Nepenthes mix with no apparent ill effect.
>
Both perlite and vermiculite are also used widely as hydroponic
mediums because of their water retention capabilities (among other
things). I've also read in a few places that perlite will eventually
break down but over a number of years. Though this break down may
only occur under the conditions used in hydroponics - the info wasn't
specific. You will probably find information on both perlite and
vermiculite if you check info sources on hydroponics.
Hope this helps
Michael Reardon
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