Volcanic rock as potting material
 

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

Volcanic rock as potting material
 

Gal,

There are a variety of inorganic, inert media on the market, and each has
its own properties in relation to moisture-holding capacity, capillarity,
mineral buildup, etc.

Lava rock is known for the mineral buildup problem, but that is affected by
the purity of your water supply, the chemical source of your fertilizers,
it's concentration, how often you flush the pots, etc.

Check out the info on "semi-hydroponics" at the URL below. You may find it
useful.

With any such medium, you're going to have to use a complete nutrient, as
the plant gets essentially nothing from the medium. Personally, I think the
same is mostly true for organic-based media as well, or at the very least,
the nutrition coming from the medium is insufficient.

--

Ray Barkalow First Rays Orchids
http://www.firstrays.com
Secure Online Ordering & Lots of Free Info!


"gal" wrote in message
om...
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

Volcanic rock as potting material
 

gal,

I see the volcanic rock mostly from plants that come from Hawaii (imagine
that from volcanic islands).

It works for them but I find that I have a lot of root loss when I try to
grow in pure rock. Remember that each plant is different and requires more
organic matter (bark, moss chunks, coco husk) than other plants.

The type of pot you grow in also affects the medium you put in the pot.
Plastic pots reduce evaporation so a very dense medium will not dry out as
quickly in plastic as it would in clay.

Try growing your Dendrobium for a while in the rock before you convert the
other plants in your collection. You may find that it worked great for the
grower you bought it from but with your watering schedule it may prove to be
too dry for your culture.

Remember that you don't want to be a slave to your plants. My philosophy is
that if it won't grow under my culture then I shouldn't grow it!

Good growing,
Gene

Volcanic rock as potting material
 

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

Volcanic rock as potting material
 

Gene Schurg wrote:

gal,

I see the volcanic rock mostly from plants that come from Hawaii (imagine
that from volcanic islands).



Umm... Isn't the local legend that if you take rocks from Hawai'i
that Pele gives you a really hard time? There is a curse or
something... *grin* No, I don't believe in curses, but if you do,
perhaps you should insist that your plants be shipped bare root.

Rob (wishing he was in Hawai'i)

--
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

Volcanic rock as potting material
 

Hmm....

Could that explain why plants I get from Hawaii in lava rock die? Maybe
it's not my culture.


"Rob Halgren" wrote in message
...
Gene Schurg wrote:

gal,

I see the volcanic rock mostly from plants that come from Hawaii (imagine
that from volcanic islands).



Umm... Isn't the local legend that if you take rocks from Hawai'i
that Pele gives you a really hard time? There is a curse or
something... *grin* No, I don't believe in curses, but if you do,
perhaps you should insist that your plants be shipped bare root.

Rob (wishing he was in Hawai'i)

--
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

Volcanic rock as potting material
 

I routinely grow certain genera - mature Catts and Dends - in plain rock,
and they flourish. I also use Aliflor, and sometimes a mix of both. But,
for fine rooted plants, or small to miniature Catts or Dends, I prefer a mix
based on CHC to avoid root damage.

Diana

Volcanic rock as potting material
 

Umm... Isn't the local legend that if you take rocks
from Hawai'i that Pele gives you a really hard time?

I *think* it's from the actual volcano, not necessarily
the volcanic rocks laying around all over the place. :)

Rob (wishing he was in Hawai'i)

Tracey happy that I am :)