I have almost no orchids in plastic because my orchids spend the summer outside and they have to be able to tolerate the occasional rainy week. *A plastic pot can be a place for roots to die when the weather stays wet. *Another problem is that an orchid in a plastic pot of bark is top-heavy and incompatible with a good gust of wind. *But most orchids can be grown in almost anything if conditions are properly controlled. *Moss soaks up water like a sponge and I always found orchids grown in sphagnum had a zone of dead roots in the middle of the pot. *And the stuff breaks down quickly and orchids in it need to be repotted more frequently than I want to be repotting. *It doesn't work for me, but it's great for people have the right conditions.