>From: Perry Malouf <pmalouf@access.digex.net>
>One big Nepenthes grower told me that he doesn't use
>perlite because it can release fluorides (and other
>trace compounds) into the medium.
There was some discussion of this on the Orchids list digest lately. One
contributor said that he had some perlite analyzed and did not detect
fluoride. Another grower mentioned that he lost some Phragmipedium besseae to
symptoms that resembled fluoride poisoning when they were grown in a perlite
mix. OTOH, I have a healthy Phrag. besseae which has been growing in pure
perlite for the last 6 months. Is it possible that different batches of
perlite have different mineral content? I use the Peter's brand mixed with
bark and sphagnum for my Nepenthes alata, and I have had no problems. I do
notice, however, that some of the material sinks and is a different color.
Some sort of mineral contaminant? I use only the material that floats.
cheers,
Nick
Nicholas Plummer
nplummer@umich.edu
http://www.umich.edu/~nplummer/homepage.html