Can I use this to plant orchids in?
 

I found this piece of grapevine wood and was wondering if I could use it to hold my orchids. I have a moth orchid, a vulystekeara, and a zygopetalum that I would like to put in it. It is about 2 ft long , the Gap in the center is about two inches thick and three inches deep. Should I use orchid bark or sphagnum miss to keep the roots in? Would this even work?

You need to keep your orchids in separate pots. The moth orchid (Phalaenopsis) needs to dry out between waterings. The other two like to be on the damp side. And there is always the potential, if plants share a pot to also end up sharing diseases. (For the same reason, one should never use the same water for multiple plants) That is a beautiful piece of wood. Perhaps you could place plants in separate pots in there. Or save it until you get an orchid that really wants to grow mounted, like a Laelia anceps, and grow a beautiful specimen.