On 18 Mar 2003 23:41:50 -0800, (gal)
wrote:

Hello,

I bought a Dend that is potted in 100% small red porous pebbles, which
I think is volcanic rock. This is the most common potting material for
plants here (Israel) and special orchid potting material is not easy
to find.
All my orchids are potted in a mixture of moss, bark and charcoal but
after having a look at the new Dend and its roots I am thinking about
repotting everything with volcanic rock.

The advantages as I see them a
Good drainage and good air flow through the roots. I was surprise to
see that the rocks do not dry very quickly and I think I will have to
water every five to six day. Future more it is easy to have a look at
the roots by removing the top layer of the rocks.

The disadvantages a
The rocks will accumulate slats and fertilizing material and will have
to be replaced. Since there is no organic matter I am worried that
the plant will get "less value" from the potting material.

I would appreciate your comments.

Regards

Gal

I find the rock breaks down or crumbles leaving very sharp edges
so that I tend to get nicked. It is very light weight. The
light weight pot may create a problem when you try to keep the
plant upright. I think one of the reasons growers use the
material is they plan to ship the grown orchids to a better sales
area. Set the small pot in a clay pot about 2 sizes larger.
Usually that will provide enough bottom weight to keep it
upright. Normally you do not need to fill the larger pot with
any material. If you need it weighted, try smooth gravel to add
weight and help keep the little pot centered.

SuE
http://orchids.legolas.org/gallery/albums.php