Some orchids may be bought as potted plants at practically every florist’s and garden centre and we have come to regard them as quite common and not at all precious plants. Included among their number is one of the best-known and most popular of orchids — Paphiopedilum callosum.
Vietnam, Cambodia and Thailand are the home of this terrestrial species. There it grows on the damp mountain slopes in a thick layer of humus, in moss-covered valleys as well as in low grassy areas. The leaves, which are arranged in two rows in a low rosette, are pale green chequered dark green and measure about 20 to 25 cm (8 to 10 in) in length. This, in itself, indicates that the plant is a species that likes warmth and shade. Species that like full sun (for example P. spicerianum) have the leaves coloured a uniform green.
The, about 10 cm (4 in) across, are produced on an upright scape, about 30 cm (1 ft) high, in winter or early spring. As a rule there is only one scape, but large, older plants may have as many as five flowers.
Young paphiopedilums should be grown in a mixture of chopped sphagnum moss with bits of polystyrene or charcoal added; older, established plants require a richer mixture with an addition of beech leaves and peat.
The main preconditions for success in growing these orchids is constant heat (usually the temperature of a modern home will suffice) and moisture, which may be ensured by using a humidifer and by covering the surface of the compost with green sphagnum moss. Like all orchids, paphiopedilum does not tolerate moisture that lingers permanently on the roots and therefore the plants should be watered in the morning so they can dry out a little overnight.
Naturally, the most suitable conditions for growing these, and other, orchids are provided by indoor plant-cases and glasshouses, the bottoms of which also generally meet the requirement of deeper shade. Several species are suitable for growing as house plants, for example P. glaucophyllum and most hybrids.