Hi Sbg, I always thought that Glaucidium was a genus of 1 species, so I tried google, all it came up with was a lot of small owls, but another or common name for G palmatum is japanese wood poppy, which is the only reference to japan that I could find.
Glaucidium palmatum is a fully hardy slow growing rhyzomatous perennial from northern Japan, and grows best in a cool moist climate, in humus rich, leafy moist soil in partial to deep shade, out of cold drying winds, having said that, I don't grow it, and never grew it at work, so can't give you any tips, sorry, Derek.

I'm looking for info for a mate who says he has G japonicum in his greenhouse but needs info on it in the ground. He has a link to a nursery in Japan so I suspect that is where he got it from.
thanks for your input Derek.

It's one of those plants you fall in love with and is an absolute bugger to grow. I can sometimes get it to flower two years in a row, then it disappears. The words "prima donna" spring to mind.

Edrom Nursery have some details about it on their website. You can email them for more information. The plants they have in stock are too large to send out but they are available at the nursery or at any of the shows they will be visiting.

thanks for the help chaps and chapesses.