Sorry I'm jumping in so late on the conversation, but I am aware of three separate parts of the coconut that are commonly used in orchid growing:
- The pith surrounding the hard shell is what is chopped up and sold as "coconut husk chips", as has been stated. Soaking them for a couple days in calcium nitrate and/or magnesium sulfate (Epsom Salts) solutions helps attract the naturally stored sodium chloride, which can be toxic to the plants. The CHC is a great medium for water-holding capacity.
- That pith, if shredded, is sold as "coconut husk fiber" or "gorilla hair", and it is a good medium for stuff that likes to dry out quickly.
- The shell of the coconut, once the copra is removed, can be used as a pot!