Repotting oncidium with lava rock

[Mercurianmad]

Hi guys! I’m going to be repotted my wrinkled oncidium and I want to ask you if I should use just lava rocks or a mixture of 40 percent lava rock, 10 percent perlite, 20 percent sphagnum moss and 30 percent bark chips?

I know once I repot the orchid I’m going to have to toss one of the pseudobulbs, as it is squishy and getting yellow green...no idea what the roots are like but as I said the bulbs are wrinkled.

Help is appreciated.

---------- Post added at 11:02 AM ---------- Previous post was at 10:58 AM ----------

Also is lava rock good for moth orchids?

[Leafmite]

I grew large Oncidiums in pure lava rock/clay pots in the window. You need to watch the roots you can see closely and, when they turn white, soak in water until the roots are green again. My large Oncidiums really grew well this way (I had to divide them every six months and gave them to everyone I knew. I finally gave away the last of the divisions when I joined an orchid society).

When I started growing under lights, I tried a few Oncidium Twinkles in small lava chips but I didn't keep up well with the watering. I might try again with the one that grows in the terrarium and the one that grows in the window.

[SouthPark]

Originally Posted by Mercurianmad

Also is lava rock good for moth orchids?

For me, I just have one mini phalaenopsis orchid (aka a 'moth' orchid) - lava rock has been excellent.

I live in the tropics. And I use 5 to 8mm average diameter lava rock pieces for my mini-phal. Potted in good drainage pot. Really great results.

I just water the media toward the SIDE (toward the rim) of the pot - so the media furthest from the plant is quite wet. The regions closer-in toward the plant is less wet ----- ie. I try to keep the regions closer to the plant lightly moist only - but not soaking/dripping wet. Has been working very well.

I follow the same kind of approach with the watering of my phragmipedium and paphiopedilum and other orchids - which also grow in lava rock (scoria).

[Mercurianmad]

Just repotted the oncidium. The previous growers buried the lowest pseudobulb and it was rotten. I also had to remove one of the young pseudobulbs on the outside of the plant because that was squishy as well. Can you guys take a look at these pictures and tell me if I planted this properly? All the pseudobulbs bulbs are above the potting material.! And the newest one is toward the center of the pot.

[Leafmite]

I honestly have no idea if that will work or not. It seems to be in bark and I do not grow in bark. If you have had squishy new growths, I would water from the bottom instead of the top so that water doesn't get on the pseudobulbs.

As for growing Phals in lava rock...it depends. I have found that the hybrids do quite well in it (again, soaking until the roots turn green each time) while the Phal bellina has been doing fantastic in NZ sphagnum moss so I will be keeping it in that.

[SouthPark]

MM ..... if bulbs get mushy, then the first step would be (not now though, since you've repotted already) ----- to check the media and roots. To see if the media is super wet or dripping wet. If dripping wet all or most of the time, then that could lead to issues like rot.

The other consideration is air-movement. Adequate air-movement often cuts down or eliminates on fungal and/or bacterial activity in one region or another (on the plant).

Your new potting arrangement - looks ok. Just ensure suitable growing temperatures, suitable lighting levels, and ensure the roots don't get starved of oxygen - which can often be helped by not allowing the media to stay super wet for relatively long periods of time. Your new potting arrangement and watering technique will likely provide the required conditions.

[Mercurianmad]

Thank you everyone. I was hoping to pot with lava rock but we are under quarantine and, with no mailboxes
In my town the post office has them. And I can’t get them. Im supposed to be getting some lava rock sent to the house in the next few weeks. Can I repot the orchid again when i get them?