NICE DC!! Any chance you remember where you got that neat round lava rock from?
My partner grows his ping collection on lava rock as well. We get them from the local aquarium store. The rocks are always sitting in a tray of water. They do pretty well. (Also pictured is a newly acquired dendrobium lichenastrum and a piece of my (struggling) angraecum distichum)
Seeing that they wick and hold water pretty well, I was also inspired to try a few orchids
Here's a schoenorchis fragrans. It hangs freely and is misted once a day. I've spotted some fat new roots growing behind it into the rock
Lepanthes telipogoniflora, sitting in a dish of water
Also experimenting with this tiny chiloschista. My environment isn't very humid, but the lava rock stays moist for at least half a day after I spray it in the morning. So far I think she likes it. I am fully claiming credit for all those new root stubs which weren't there when I acquired it
Now for my concerns:
1. I have two sophronitis mounted on large chunks of lava rock, and while they are minis, I know that one day they will overtake the rock with no way to remove them. proceed with caution when mounting sympodial orchids.
2. Salt build up in the rocks. For pings which you probably will never need to fertilize, this isn't a problem. For orchids, it might be. Hopefully someone else with more knowledge can chime in on foreseeable problems with fertilizer buildup on lava rock.
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I've tried breaking the rocks with hammers, slamming it into the concrete, using a make shift chisel via flat screwdriver, and the easiest for me is to just pick out a rock that's the right size at the pet store