I remember the first Paphiopedilum flower I saw: it was a P. Rothschild, among the most exotic and lovely of all flowers (at least to me) and it immediately shocked me. Sometimes called Lady Slipper Orchids, the Paphiopedilum have some of the most striking and beautfully odd flowers in the world. These orchids are known especially for their swollen lips, which have enlarged over the eons into a bucket or container above which the brilliantly colored petals and dorsal sepal hover. This lip, however, is a delightful trick of nature. Glistening with wax, it attracts bees and pollinators that believe they have discovered a source of nectar, only to fall gracelessly into the flower and then crawl out, dragging pollen with them. Paphiopedilum are intermediate orchids, although if you can grow healthy African violents, you will probably do well with these flowers.
Taxonomy and Structure:
Paphiopedilum belong to the Cypripedioideae subtribe. There are 60 species of Paphiopedilum and thousands of registered hybrids. Aside from the enlarged lower lip, Paphiopedilum blooms are notable because of the structure of their petals and sepals. The dorsal (top) sepal is typically enlarged to form an umbrella over the cup-like lip, while the two remaining sepals have fused into a tunnel that directs pollinators out the back of the flower. The side petals are typically angled downward and may be enlongated and blade-like or even spiralled and twisting like hair braids. Unlike many other popular orchids, Paphiopedilum are terrestrial (as opposed to epiphytic) and grow in leaf-litter on the forest floor. They do not have the strong clinging roots of other common blooming orchids.
Paphiopedilum are native to the Asian tropics, where they grow on the forest floor in mid-elevations. Although there are a number of groups of Paphiopedilum, as a rule they prefer bright, filtered light.
Paphiopedilum prefer a relative humidity of around 50 percent, making them less needy for humidity than some of their more popular cousins. They do best potted in pure pine bark, perhaps mixed with a small amount of sphagnum moss to help with moisture retention. As a rule, Paphiopedilum should never be allowed to completely dry out, but the interior of the potting media should always be moist. They do not require any dry season. The faster draining your potting media, the more frequently you will have to water them. Wrinkled and drooping leaves are a sign of water stress.
Paphiopedilum are light feeders and should be fed a 1/4-strength balanced liquid fertilizer during the growing season. You can also drop a few pellets of a controlled release fertilizer on top of the potting media.
Paphiopedilum thrive in slightly cooler temperatures than warm-house orchids like cattleya and vandas. They can tolerate cooler nights (down to 60˚F) and do not like the intense heat of tropical summers.
There are two general groups of Paphiopedilum in terms of blooms: single flowers and multiflora plants. As the name implies, single bloomers send up one flower per bloom spike. This group includes P. insigne and P. hirsutissimum, which are sometimes referred to as "toad" orchids because of their warty, mottled flowers. Much more popular recently are the multiflora bloomers, which send up spikes with multiple blooms. This group includes the enchancting P. rothschildianum and the P. philippinense. The P. rothschildianum in particular might have the world's most beautiful flowers, but it can be difficult to achieve the right mix of bright, constant light and high humidity it requires outside of a greenhouse.
Potting and Media:
Paphiopedilum are terrestrial orchids and thus thrive in standard pots. Most growers use plastic pots because they help retain moisture better, and Paphiopedilum do best in a slightly damp environment. The most common Paphiopedilum growing media is a fine pine bark mix supplemented with a long-fibered sphagnum moss for moisture retention. You can also use expanded clay aggregate pellets or lava rock, but you will have to water more frequently. Paphiopedilum are not rapid growers (young plants can, in fact, require years to achieve their first bloom), so pots larger than 8" are extremely rare.
Paphiopedilum can be challenging plants to grow successfully, but the effort is well rewarded. These plants are notoriously expensive, in part because they do not clone well from tissue culture. As a result, the vast majority of Paphiopedilum plants are started from seed, which requires years to produce a viable plant. Expect to pay top dollar for even a moderate sized Paphiopedilum. They can, however, be propagated at home during repotting. Gently prize apart the roots and sever the rhizome, being careful not to cut into the leaf base, then pot the pieces up separately. In general, Paphiopedilum plants should be repotted regularly to refresh the potting media, even if they haven't outgrown their pots.