Paphiopedilums, the lady's-slipper orchids, originate in the jungles of
the Far East including Indonesia. They are semiterrestrial, growing in humus
and other material on the forest floor, on cliffs in pockets of humus and
occasionally in trees. They are easy to grow in the home, under lights or
in the greenhouse.
Light is easier to provide for paphiopedilums than many other
types of orchids. They require shady conditions, as in the home in an
east or west window, or near a shaded south window. In the greenhouse,
shade must be provided. Give about 1,000 to 1,500 foot-candles. In the
home, fluorescent lighting is excellent; suspend two or four tubes 6 to
12 inches above the leaves.
Temperatures for paphiopedilums cover a considerable range. Paphiopedilums
are traditionally separated into two groups: the warm-growing mottled-leaved
types and the cool-growing green-leaved types. A third, increasingly popular
group is the warmer-growing strap-leaved multi-floral paphiopedilums.
Warm-growing types should be kept at 60 to 65 F during the night, and
75 to 85 F or more during the day. Cool-growing types should be kept at
50 to 60 F during the night and 75 to 80 F during the day. However, many
growers raise all plants in the same temperature range with excellent
results. The plants can stand night temperatures in the 40s if necessary
(as when grown outside in mild climates), as well as temperatures to 95
F. Care must be taken to protect the plants from rot when cold (keep humidity
low, and avoid moisture on leaves or in the crowns of the plants), and
also to protect from burning when hot (shade more heavily and increase
humidity and air movement around the plants).
Water must be available at the roots constantly, because all plants
in this genus have no pseudobulbs. All of these plants need a moist medium
- never soggy, but never dry. Water once or twice a week.
Humidity for paphiopedilums should be moderate, between 40 and
50 percent, which can be maintained in the home by setting the plants
on trays of gravel, partially filled with water, so that the plants never
sit in water. In a greenhouse, average humidity is sufficient. Using an
evaporative cooling system in warm climates can increase the humidity.
Air movement is essential, especially when humidity is high.
Fertilize on a regular schedule, but care must be taken to avoid
burning of the fleshy, hairy roots. High-nitrogen fertilizers (such as
30-10-10) are recommended when potted in any fir-bark mix. In warm weather,
some growers use half-strength applications every two weeks; others use
one-quarter strength at every watering. It's important to flush with clear
water monthly to leach excess fertilizer, which can burn roots. In cool
weather, fertilizer applications once a month are sufficient.
Potting should be done about every two years, or as the medium
decomposes. Seedlings and smaller plants are often repotted annually.
Mixes vary tremendously; most are fine- or medium-grade fir bark, with
varying additives, such as perlite (sponge rock), coarse sand and sphagnum
moss. Moisture retention with excel-lent drainage is needed. Large plants
can be divided by pulling or cutting the fans of the leaves apart, into
clumps of three to five growths. Smaller divisions will grow, but may
not flower. Spread the roots over a small amount of medium in the bottom
of the pot and fill with medium, so that the junction of roots and stem
is buried 1 .2 inch deep in the center of the pot. Do overpot; an average
plant should have a 4- to 6-inch pot.