What little I know of ferns from spore is a fascinating two step process. a little plant that doesn't look much like a fern comes from the spore. After some period of development the male portion (roughly equivalent to pollen) works its way up the plantlet with half of the needed genetics to what would be roughly the stamen where the other half of the genes are. The conditions most be VERY moist for this movement. In this respect many consider ferns to reproduce asexually, but that's kind of fuzzy since there is that half and half from two different cells.
Although ferns are extremely old and considered a less complex life form, their reproductive cycle is more complex than flowering plants.
Here is a web site that does an excellent job of explaining this process without becoming technical; even I can understand it! :whistling:
http://www.home.aone.net.au/~b...
I too have heard ferns need sterile environments, but mine keep popping up new ones all over my fern garden - often in the middle of other ferns that I have to lift to get the rouges out! My ferns are all in a mostly shady area about 12' square; like all my gardens it is a raised bed, heavily mulched with black bark mulch (the black is just for esthetics), and the area stays moist but well drained. I don't encourage them to grow from spore by laying fronds on the ground or collecting and sowing them (I certainly don't discourage them either!). I do get some new ferns that are almost like strawberries from short runners (skinny rhizsomes) - primarily Japanese Painted Ferns - but it amazes me ho many are little sprouts.