Cypripedium japonicum and formosanum - The Asian Slipper Orchids

C. japonicum and C. formosanum are the asian slipper orchids and are very closely related sometimes C. formosanum is described as C. japonicum var formosanum. They do differ with C. formosanum being larger growing and C. japonicum seemingly handling damper conditions that its close relative.

Cypripedium formosanum is a wonderful rare orchid that is at home in cool climate gardens, it does require excellent drainage and will grow well in a terracotta pot as long as the growing medium is open and free draining.

Often called the Formosa Lady's Slipper these are a large flowering species with great foliage as well as fantastic flowers. The two large fan shaped leaves are slightly pleated, the flower is a large slipper shaped form with pink and white markings, it appears early in spring and contrasts well against the mid to deep green foliage.

This is deciduous species that will be dormant from summer to when the foliage emerges in spring.

Propagation and Care

Best grown in the ground with an amended soil, dig in some perlite and grit to ensure good drainage, best in a raised garden bed in most conditions. We use a mixture of good quality potting mix, perlite and some course grit. As the plant spreads by runners (stoloniferous rhizomes) we tend to use a largish squat pot to allow a little room. In frost free zones you can grow Cypripedium formosanum in the garden, some protection is essential.

Best grown in a position where they receive good filtered light as they are naturally an understory plant. Morning or late afternoon sun of a few hours is also recommended.

Fertilizer

A liquid fertiliser such as a seaweed type diluted to 1/3 strength applied in early spring at first signs of achieve growth and every 2 weeks until late spring to early summer is usually adequate.

Problems

Poor flowering - often caused by warm soil temperatures especially when grown in containers.

Shoots and Flowers destroyed by frost - Both C. japonicum and C. formosanum like to flower early and if a late winter blast brings a second round of cold temperatures and frost, the new shoots and flowers will suffer. Grow indoors in these situations.