Volcanic Red Lava Rock as S/H media

[rodrigo]

I've been reading on S/H for orchids, and I really want to try it.

As a matter of fact, I just finished re-potting 2 cattleya mericlone seedlings I bought at a recent Orchid Show in S/H but using Red Volcanic Rock as the medium.

You see, over here we do not have access to the baked ceramic stuff, but we have plenty of this type of cheap lava rock and they sell it in different sizes.

Because of the extreme heat that this material went through when it was in lava form, it is extremely porous and absorbs lots of water.

It is used extensively around here for hydroponic operations on vegetables and the lot.

Mixed with charcoal (50-50) it is my favorite substrate for Cymbidiums. Works very well.

I just want to know if somebody else has tried it on a S/H operation. Any pros and cons?

Thanks,

Rodrigo

[Bird Song Farm]

I use the red lava rock for a number of my plants and have no problems with it.
Al

[trdyl]

It is not the best thing to use but it should work just fine once the roots have grown down into the reservoir.

[Izzie]

Originally Posted by trdyl

It is not the best thing to use but it should work just fine once the roots have grown down into the reservoir.

Could you explain why it's not the best to use?
Obviously, PrimeAgra and the like will always be the go-to media for s/h I'm sure, but what are the downfalls of volcanic rock? I bet it doesn't wick quite as well, anything else?

[rodrigo]

Originally Posted by Izzie

I bet it doesn't wick quite as well...

I have a different experience on that.
My Cymbidiums "bake" in the sun all day, and the red lava rock gets totally dry on the top surface.

But the next morning, after a whole night of cooler temperature, the rock on the surface is full of moisture again (deep red, full of water).

What happens is that during the night, the moisture at the bottom of the pots "wicks" its way all the way to the top again. (and the pots I use do not have a reservoir at the bottom like the S/H pots do)

So there is some heavy "wicking" action going on with this material.

Rodrigo

[DelawareJim]

Originally Posted by Izzie

Could you explain why it's not the best to use?
Obviously, PrimeAgra and the like will always be the go-to media for s/h I'm sure, but what are the downfalls of volcanic rock? I bet it doesn't wick quite as well, anything else?

According to Ray, the volcanic rock (lava rock) is like PrimeAgra turned inside-out. If I recall correctly, it wicks well but also really holds the mineral salts and doesn't flush well.

Search for "lava rock" on the OB and you'll find several older discussions.

Cheers.
Jim

[rodrigo]

Hi Jim!

Originally Posted by DelawareJim

Search for "lava rock" on the OB and you'll find several older discussions.

I just did that and only this thread showed up

Originally Posted by DelawareJim

.... it wicks well but also really holds the mineral salts and doesn't flush well.

I have over 100 Cymbs that have been growing from flask on Red Lava Rock + Charcoal (50-50) for the past 2.5 years.
I water once a week, alternating one nutrient feeding per week, and one copious rain water flushing the next week, and I have not had any salt accumulation problems.

Now, if this is the only bad thing you can come up against red lava rock media for S/H. It's easily solved.
Just flush "the h...." out of them with cheap clean rain water

Rodrigo

[trdyl]

Originally Posted by Izzie

Could you explain why it's not the best to use?
Obviously, PrimeAgra and the like will always be the go-to media for s/h I'm sure, but what are the downfalls of volcanic rock? I bet it doesn't wick quite as well, anything else?

I have experienced not so good wicking in past with lava rock. Of course the size of the rock probably had a lot to do with it also. If it works for you why not use it.

[Connie Star]

Hi Rodrigo, and welcome to OB. I have been to Costa Rica a number of times and love your country. I won't waste your time practicing my Spanish other than to say Pura Vida.
I'm trying S/H using Prime Agra and I found that salt build-up was a problem on the top until I started alternating a rain water flush with the recommended special S/H fertilizer. So, I think I am doing the same thing you are describing.
I looked at the CRSeeds web site. Are the miracle fruit seeds you sell viable for growing? I've had miracle fruit and I would love to see if I can grow some indoors.

[Izzie]

Thanks for the input/clarification.
Now if only I could find a small enough grade of volcanic rock at lowes and home depot or my garden centers.