wendy7 wrote:

Yes Francis, I phoned them about a year ago, they are down towards
San Diego, I didn't keep the info as it was just way too expensive
for my liking. It is a type of rock found in Australia.
There were two choices but the gold was the one everyone was raving
about that had tried it.
Someone in our group mentioned the name of the rock (dia-?something)
My memory is so bad so maybe someone will know.


There is something sold as diatomite
(http://www.maidenwelldiatomiteaustra...ts/default.htm) that
I've seen used to very good effect on phrags... Is that what you are
thinking of? Most of those rock or ceramic based media are all working
on the same basic principle. You aren't extracting any nutrient value
from them, just using them to keep the plant from falling over. All of
the nutrition comes from the fertilizer you put in your water.

While you might think that rock is rock, there are some differences
in the way they hold water and wick water up from the bottom of the pot
(usually some sort of reservoir). This probably has an effect on plant
growth. Ray has done some actual science on that, at least for a few
brands. Check that out at http://firstrays.com

I've seen some pretty amazing plants grown this way. In all sorts
of different brands of rocks. The only tricky part seems to be
selecting a good fertilizer, and I think there might be some issues for
plants that need rest periods. I'm trying out some of Ray's media right
now (a full week into the experiment!) to see if it will work for me.


Rob

--
Rob's Rules: http://www.msu.edu/~halgren
1) There is always room for one more orchid
2) There is always room for two more orchids
2a. See rule 1
3) When one has insufficient credit to purchase
more orchids, obtain more credit
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