there are a few species which actually do just fine in non-sterile culture, most of them are the temperate climate species (I have heard that Goodyera is one of them, I am currently conducting an experiment with those...I'll give more details in a second). You just simply spread the seed in a pot with some already existing mature plants. I have also heard of spontaneous growth on moist slabs of tree fern, though I know alot of growers are shying away from using tree fern since it is expensive, non renewable and has a history of being non agreeable with certain plants. Pleurothallids are notorious for spontaneous germination on tree fern.

Ok, so for the experiment:

My control group is sowing on leaf litter from a nearby colony (but not in too close of a poximity as their tubers are close to the surface and the seed is not collected from that group but rather from a venerable house of orchid seed storage). The existence of the right fungi should be existing in the leaf litter. Group A will be sown on "sterile" (more correctly put...pasturized) chopped sphag. There are the two non sterile groups. Then, the other two will be sown in sterile agar based mediums for terrestrials.

I have a book that list two known non-sterile propogation species, I'll list them tomorrow.