Here is my longissimum - it grows in a 10 inch net pot, sits in a saucer of water and grows in Catt light. This is a very demanding orchid regarding its water requirements but if kept moist enough, it is very easy to grow.
I line the basket with sphag, use p'nuts in the bottom half of the basket and the top part is a moisture holding mix. If you look closely you can see the roots winding through the net pot. It wants moisture and air at the root zone. In my g/h I would not be able to keep the roots as wet enough mounted.
If your net pot doesn't have the big holes this one has, you won't need to line it with sphag to hold the media.
Bulb longissimum LUR_5417 by
kentucky4, on Flickr
Brooke