Oncidium repot in lava rock squishy roots wrinkled pseudobulbs

[SouthPark]

A deep pot, or big pot of lava rock could probably be workable for a dry environment. If put the orchid in the middle of a big pot, and water the scoria in a thick band around the sides of the big pot, then it might be possible for a lot of that scoria to remain wet for quite a while.

Could also consider the size of the pieces of lava rock - eg. using relatively smaller pieces, than larger pieces.

Although, this all could depend on the number of orchids in a collection, and other things. Otherwise, even with a small pot - if enough effort is spent in compensating for the dry area (eg. water more) --- then something workable could probably come out of it.

In a very dry place, I think I'd likely go the way of bark mix too.