Last November I got the E-mail announcement from
Kusamono Gardens about pre-ordering plants for delivery in March 2018. I had previously grown Habenaria radiata from them. I decided also to try another Japanese terrestrial orchid, Ponerorchis graminifolia. My shipment arrived this week.
Kusamono Gardens has some cultivation information on their page regarding this plant. I found some additional information while searching:
A miniature terrestrial orchid from Japan, Ponerorchis
Hortus orchis - Ponerorchis graminifolia
Ponerorchis
Scottish Rock Garden Club - >Wisley Alpine Log
http://www.pacificbulbsociety.org/pb...hp/Ponerorchis
From all this reading, the chief problem in cultivation seems to be rotting from being too wet, and without air to the roots. In habitat, the plants grow in pockets of humus collected in crevices on rock cliffs. Kusamono recommends using kanuma or pumice, mixed with sphagnum to hold more water.
I'm going to use pumice mixed with sphagnum.