Well-drained growing media (was Oh No! A Boophonedisaster!)
Eugene Zielinski (Tue, 06 Oct 2009 17:48:45 PDT)

Another option is to check around for "sponge rock". This is large sized
perlite that some orchid growers use in their growing media.

Eugene Zielinski
Augusta, GA
USA

[Original Message]
To: Pacific Bulb Society <pbs@lists.ibiblio.org>
Date: 10/6/2009 8:26:18 PM
Subject: Re: [pbs] Well-drained growing media (was Oh No! A

Boophonedisaster!)

On 5 Oct 2009, at 18:02, Leo A. Martin wrote:

I have wanted to try some of the larger-particle perlite, often used for
insulation, but I have been warned much of this is very high in

fluoride

and toxic to plants.

Change that "is" to "may be". If you feel you must use insulation grade

perlite

in spite of these warnings, you can mitigate the risk by adding lime to

the mix

as calcium fluoride and magnesium fluoride are very insoluble and thus

the

presence of Ca++ and Mg++ ions in the soil will tend to soak up any F-

released

by the perlite.

--
Rodger Whitlock
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