cattleya in soil/sand mix
 

I just spent a little bit of time pulling roots of a big cattleya plant out of soil/sand. The roots had grown out through holes in the bottom of the pot, through the plastic drainage grill which the pot sits upon, and established themselves not just on top the sand/soil underneath -- but also big mass under the surface. The big clump of roots pulled out from under the soil was very nice - very healthy. The spreaded-out clump of roots wasn't deep in the soil, but definitely thriving under the surface. I believe that other people have likely encountered the same situation.

I cut the roots off, as I don't mind the plant from getting set back a bit. I figured that it could be risky for the plant to pick up some possible nasties (in future) from the sand/soil mix. This is one of my favourite plants. But it looks like the plant could definitely just keep growing without issue with the roots in the sand/soil. The sand/soil does get wet, but not water-logged. I use a spray wand to water the pot, and water does run through the good-drainage pot and into the sand/soil under the pot.

The media in the pot is volcanic rock. There's lots of nice roots inside the pot already.

When new roots are growing, they are quite adaptable; once they have grown, they're not.

Every plant growing in semi-hydroponics will put its roots right into the reservoir and grow there very nicely. Pot the plant up and submerge the roots that grew elsewhere, and they'll suffocate, die, and rot.

The ability for organisms to adapt to environment is absolutely fantastic.

The adapted submerged roots of orchids is definitely interesting. With submerged roots, it will be interesting to see whether those roots require oxygen. And whether the plant supplies those submerged roots with oxygen.