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***********      Cattleya      **********

Cattleyas are among the most commonly grown orchids, and their
culture is often used as the basis for comparison with other
types of orchids.

The flowers in cattleyas and their related hybrids come in
many colors. Culture varies only slightly among most of these
groups; this cultural information is a general guide to
"standard" cattleya culture.

Like most other cultivated orchids, cattleyas are epiphytes,
or air-plants. Because they are epiphytic, they have developed
water-storage organs, called pseudobulbs, and have large,
fleshy roots covered with a spongy, water-retentive velamen.
They are accustomed to being dry at the roots between
waterings, and therefore should be potted in a very porous,
free-draining medium.

LIGHT is one of the most important factors in growing and
blooming cattleyas, whether in a greenhouse setting or in the
home. Bright light to some sun must be given to the plants,
but no direct  sun in the middle of the day. This means at
east, shaded-south (as with a sheer curtain) or west window in
the home, and 30% to 50% of full sun in a greenhouse (3,000 to
5,000 foot-candles). Leaves should be a medium green color.

TEMPERATURES. Recommended temperatures are 55 to 60 degrees F
at night and 70 to 85 degrees during the day. Seedlings should
have night temperatures 5 to 10 degrees higher. A 10 to 20
degrees differential between day and night is recommended,
especially for mature plants. Higher day temperatures can be
tolerated (up to 95 degrees F), if humidity, air circulation
and shading are increased.

WATER should be provided in two ways: in the pot by watering
and in the air as humidity. Watering in the pot is dictated by
many criteria - size and type of pot, temperature, light, etc.
Mature cattleyas need to dry out thoroughly before being
watered again. Seedlings need slightly more constant moisture.
Compare the weight of a dry pot of the same size and type of
medium; it can indicate if a plant needs water. A freshly
sharpened pencil inserted in the potting medium can be an
indicator of moisture. If in doubt, it's best to wait a day or
two until watering. Plants in active growth need more water
than plants that are resting. Water below 50 degrees F may
injure plants, as will softened water.

HUMIDITY. Cattleyas need 50% to 80% relative humidity. This
can be provided in the home by placing the plants on trays of
gravel, partially filled with water so that the plants stand
above the water. Misting the plants in the morning only is
helpful in dry climates. Air should always be moving around
the plants to prevent fungal or bacterial disease, especially
if high humidity and/or cool temperatures exist. In the
greenhouse the humidity can be increased by wetting the floor.
Evaporative cooling increases humidity while cooling the air.

FERTILIZER must be given to cattleyas on a regular schedule.
In fir bark, a high nitrogen (30-10-10) forrmulation, or a
similar proportion, is used. High-phosphorus or bloom booster
(10-30-20) formulation may be used occasionally (every 4 to 6
applications) to make sturdy growths and promote healthy
blooming. When in active growth, plants need fertilizer every
two weeks, and when not growing, once a month. Fertilizer can
also be applied with every watering at 1/4 recommended
dilution. Thorough flushing with clear water every month is
recommended to prevent buildup of fertilizer salts.

POTTING is necessary when 1) the rhizome of the plants
protrudes over the edge of the pot, or 2) the potting medium
starts to break down and drain poorly (usually after 2 to 3
years). It is best to repot 1) just before new roots sprout
from the rhizome, 2) after flowering, or 3) in the spring

Mature cattleyas are usually potted in medium-grade potting
material; seedlings in fine-grade. Until a plant has six
mature pseudobulbs, it generally should be put into a larger
pot and not divided. If dividing a plant, 3 to 5 bulbs per
division are required. Select a pot that will allow for 2 to 3
years of growth before crowding the pot. Place a small cone of
potting material in the bottom of the pot, cut off any rotten
roots, and spread the firm, live roots over the cone. Fill the
pot with medium, working it around the roots. Pack firmly;
stake if necessary. Keep the plant humid, shaded and dry at
the roots for a while to promote new root growth. A vitamin B1
solution may help re-establish plants quickly.

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

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