Black lava rock

[phelsumatic]

Anyone ever use this stuff for you orch's.I think it would really make the plants pop but figured id ask her first.

[Swamper]

I have some really giant lava rocks in my yard and I have layed or is it laid (ouch) some vandas on top of them. The roots have grabbed on and they seem to be thriving. I have heard that in the long run there is something in the rocks that is not good for orchids, but I'm curious and always experimenting so...there you have it

[phelsumatic]

I wonder what chemically could be in them to effect the orchid's seems to me they would be beneficial.

[Swamper]

Yeah, I don't know what's in them either. I'll take some pictures for you to see if you want.

[phelsumatic]

My issue is I only keep mini's to micro's and figured it would look amazing to have some of them mounted on black rock.Yes please a pic would be great.

[BobInBonita]

Just a guess - there is usually a lot of sulfurous gas around volcanoes. If there is a sulfur residue there could be a very low pH. If you're really worried, concerned or just curious, I'd try leaching a chunk in distilled water for a while and then testing pH.

It seems that if the roots are spreading over the surface and the plant looks healthy, the rock is pretty safe.

Only other downside I can think of is that the lava rock I've seen in larger chunks is pretty light and porous. If so, will there be a mineral build-up over time? Again, the stuff I've seen has a glass like texture, even though it's porous. This should be pretty easy to rinse off any build-up.

Just a lot of guesses

[phelsumatic]

Good point regarding sulfur.I guess if the lava rock was maybe submerged the acidic water would have an effect on the roots but most of the species i keep like it wet and they come from area's with constant rainfall etc.I may try it on a few hardier types and see what happens.