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Stanhopea and Relatives

Stanhopeas bear incredible flowers with intricate and complex
structures and mechanisms for pollination, from channeled
"walkways" for insects, to buckets of a watery solution. Most
have inflorescences that grow downward, so the plants must be
potted in hanging baskets or similar containers. Flowers may be
spicily fragrant, and although the flowers are short-lived,
each plant may produce many inflorescences throughout the year.

Related genera, Paphinia and Peristeria, grow cooler and
warmer, respectively, than others in this group, and produce
upright inflorescences.

LIGHT should be bright, with direct sunlight diffused so as not
to burn the leaves. Most growers suspend these orchids due to
their pendulous inflorescences. This also brings the plants
closer to the light. Light levels approximating those for
cattleyas, or 3,000 foot-candles, are best.

TEMPERATURES for these orchids should be moderate: 52 to 60
degrees F at night, with day temperatures 68 to 75 degrees F in
the winter. Plants can stand short spells of higher
temperatures, but air movement, humidity and shading must all
be increased. Cool night temperatures seem to promote
flowering. Many species flower in the summer, and putting them
outside in the summer may be ideal.

WATER in ample quantities is important to produce strong
pseudobulbs and healthy flowers. Most growers pot in an open
medium and water frequently, especially when warm. Dry roots
lead to leaf-tip dieback, or a browning of the leaf tip.
Watering frequency can be reduced in the winter months, but
these plants should never dry out completely.

HUMIDITY should be kept at 40% to 75%, and at high levels
especially when temperatures are high. Frequent misting reduces
the chance of mite and insect infection; at the same time,
strong air movement must be provided to prevent spotting of the

FERTILIZER should be applied at regular intervals. Most growers
fertilize with a diluted concentration every week to two weeks.
For plants in bark, use a 30-10-10 high nitrogen formulation,
alternating with a 20-20-20 balanced formulation; in the
blooming season, which is mainly summer, use a 10-30-20 bloom
booster formulation. Plants grown in osmunda need fertilization
only infrequently.

POTTING is best right after summer bloom, as most plants seem
to grow year-round. Plants that rest in the winter may be
repotted in the spring. The best flowerings come from large
clumps of plants, so large baskets are usually used. An airy,
yet moist medium seems to work best, such as medium-grade fir
bark (often mixed with sphagnum peat) or osmunda fiber. Baskets
are most often lined with moss before plants are placed in the
medium; this allows the pendulous inflorescences to grow
through the bottom of the basket. Pre-moisten the potting
medium so that the roots do not dry severely after repotting.
Vigorous plants may need repotting every three years.

Prepared by: 
Education Committee, American Orchid Society 
6000 S. Olive Ave., West Palm Beach, FL 33405 
(407) 585-8666.

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