about the cat litter link from kavanaru - interesting! I checked it out, and it seems that I have small seedling diatomite from australia that I had purchased before to try with phrags and paphs. for some reason, it didn't work all that well for me though I may not have been watering properly for semi-hydro use. so, I may try that for the arietinum. I'd heard that ram's head might like neutral to slightly alkaline, but I guess I could take a pH meter and go to a spot where there are some, and test the soil there. There is a spot with tiny ones that are growing in the leaf/needle litter underneath some evergreens, but there are larger plants in places with more mixed/deciduous woods, and they are supposed to be more numerous in alkaline cedar swamps through central ny. That said, just because they are in an alkaline swamp doesn't mean that the plants themselves aren't growing over hemlock roots (like pink ladyslippers/acaule do.. and they are acidic lovers)
thanks for all the info!
that said, I found this a few minutes ago
http://orchids.wikia.com/wiki/Cypripedium_arietinum that suggests a media pH of around 6
also found on a german forum, a local north american botanist describes his attempts at growing ram's head and providing culture clues
"Cypripedium arietinum is a rather rare species distributed from the taiga of central Canada across the Great Lakes region and eastward to the Coast. Only in the Great Lakes region is it abundant, and then only rarely. It most commonly occurs in the immediate vicinity of the larger lakes, growing on bluffs and sand dunes under open, scrubby forest of conifers and deciduous species. Soils are often moderately acidic but over calcareous substrates, very well-drained and often moderately dry. The species also occurs in calcareous fens; rare in such habitat, the plants grow atop well-drained but moist hummocks in calcareous muck."
also "in contrast to my success with these species, my experience with the curious little C. arietinum has been mixed. These plants will grow well in my standard mix (mostly sand dune sand with a tiny bit of calcareous muck) in partial shade with moderate moisture levels. They are small and weak, however, and correspondingly difficult to establish. They grow in sites that often become quite dry in nature, but until established they require careful watering: too little and they may wilt fatally, but they rot easily if over-watered."