# Interesting articles: Food for thought



## paphreek (Nov 14, 2010)

As I have moved my collection from the house to the greenhouse, I've already noticed dramatic differences in how plants and media are reacting to the different environment. Most notably, the higher humidity has greatly slowed the drying out of the media. This has lead me to begin adapting my media to adjust to these new conditions. I am doing it slowly and cautiously because I know the conditions will be quite different when summer rolls around. One suggestion I have gotten from an excellent grower is to use lava rock. It doesn't break down and rot, holds some moisture, but also maintains air gaps necessary for the roots. While googling for sources to buy lava rock and stalite locally (shipping costs can be expensive), I came across this series of orchid growing articles. While not everything noted in the articles will make sense for everyone (growing conditions can vary for each of us), I did find these articles interesting. http://roseg4art.com/orchid-growing-tips-index-to-articles.htm


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## JeanLux (Nov 14, 2010)

About a year ago I got some seedlings from one of our great members, growing in lava rock, with the addition of some fine oister shell grit!!! Meanwhile I transplanted some of them in my normal bark mix, and as per today I can say that those plantlets staying in lava are growing stronger than the ones I transplanted!! (Maybe he could jump in and tell about his experience ). Since then I am adding a good part of lava rock to my usual mix, also for my catts and the plants seem to like it . Jean

ps: thanks of course for the interesting link Ross!!!


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## Paphman910 (Nov 14, 2010)

Interesting article! I found the same result with Paph sanderianum liking lava rock top dressed with sphagnum and grew much larger than the other seedling in coconut husk. At the time I couldn't figure out why the seedlings was growing so much larger than the other seedlings.

Paphman910


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## Hera (Nov 14, 2010)

Interesting......very interesting. I have some plants that are doing marginally well, I may give this a try.


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## cliokchi (Nov 14, 2010)

Hi Ross,

The late *Norris H.Powell* from '*the orchid House*' in Los Osos Ca
used volcanic rock also and received back than more CCM's
than anybody else ! 
he had plants that stayed in the same pot for many years


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## gonewild (Nov 14, 2010)

cliokchi said:


> Hi Ross,
> 
> The late *Norris H.Powell* from '*the orchid House*' in Los Osos Ca
> used volcanic rock also and received back than more CCM's
> ...




Powell did not use volcanic rock. He used a locally produced product called Airox.
It was an expanded clay or shale material, people always said it was shale but now I'm not sure, the mine was at the base of a big shale cliff but also the low land below it has vast clay deposits. It did look like little pieces of lava but it was not volcanic. It was made by heating the shale (or clay) and it popped like popcorn. It was very much like leca that is used now. Very similar to the original PrimeAgra and much lighter in weight than lava. it was originally produced as a cement aggregate I think for the Air Force when they built Vandenburg Air Force Base and all the missile silos.

Lava and leca both provide about the same benefits when mixed in growing media.
Leca is much lighter in weight and has known mineral contents where lava is heavier and may contain almost any mineral. That is why the hydroponic industry uses leca rather than lava.


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## SlipperFan (Nov 14, 2010)

Most often, plants coming from Hawaii are in black lava rock. I've used the red lava rock from places like Menards & Lowe's, after rinsing, with success for Dens, Catts and some vandaceous plants. i've not tried it with Paphs, though I do use diatomite with them.


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## cliokchi (Nov 14, 2010)

hi Lance,

is that airox stuff still available ?
he mixed it with bark ,a tiny bit off sand and crushed/chopped pinecones
thanx4your additional inormation
cliokchi


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## likespaphs (Nov 15, 2010)

a and p orchids grows using lava rock.


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## gonewild (Nov 15, 2010)

cliokchi said:


> hi Lance,
> 
> is that airox stuff still available ?
> he mixed it with bark ,a tiny bit off sand and crushed/chopped pinecones
> ...



No, they quit making in back in the early 70's.
Powell had a pretty large stock pile but when it ran out the next best substitute was pumice. Perlite was too expensive at the time and is too soft.
(Airox at the time was about $100 for a truckload and perlite about $2 per sack!)
Lava is too heavy to use in a media when plants will be shipped for sale.
Now, the expanded lecas do about the same as the old Airox. But the Airox was more jagged and irregular shaped than the current leca pebbles. The jagged shapes are better for mixing with other ingredients but I guess the round shapes like Hydroton are better for hydroponics use?


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## Ernie (Nov 15, 2010)

gonewild said:


> The jagged shapes are better for mixing with other ingredients but I guess the round shapes like Hydroton are better for hydroponics use?



Not really. Spherical media isn't as good as odd-shapes for s/h IMO. The pieces don't interlock well and leads to wobbly plants until they establish.


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## gonewild (Nov 15, 2010)

Ernie said:


> Not really. Spherical media isn't as good as odd-shapes for s/h IMO. The pieces don't interlock well and leads to wobbly plants until they establish.



Yes I agree for S/H. But for large true hydro operations the round pebbles move through automatic systems better and the plants are usually supported in some way.


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