Quote Originally Posted by Brutal_Dreamer View Post
I would not use vermiculite as it compacts when it drys out and that would cut off air to the roots. I would however as Jordan mentions use a smaller bark mixture for the fine oncidium roots.

cheers,
BD
Funny, ive never had that problem-then again, do keep my orchids damp. I have heard about that though....

You could even just mix a tablespoon with a cup of bark to lighten the mix a bit.