...on the other hand, cypripediums are shallow rooting, and although they are often sold in long toms (I do it myself for the convenience of getting more plants into a tray), they will bulk up faster if their roots are spread out horizontally in a pot that's as wide as it is deep, with at least a couple of inches to spare around the perimeter.
Using an inorganic mix, the roots are covered so that they are about 10cm below the soil surface, the pot is tapped on the floor to settle the substrate and then well watered and stood in the shade. If growth is advanced, careful staking helps.
I have found over the years that a cypripedium can be re-potted pretty much at any time of year, although I wouldn't do it when in flower, but in bud is OK. I also wouldn't re-pot when there is any chance of breaking dormancy, but that's another story.
Decisions, decisions...
PS. Remember that the flowers of
Cypripedium formosanum are not frost hardy, so if there is a late frost, please protect your plant. A cold frame is quite adequate.
