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***********         Cymbidium       **********

These orchids are prized for their sprays of large flowers,
used especially as cut flowers or for corsages in the
springtime. There are two main types of cymbidiums - standards
and miniatures. Where summers are warm (above 90 degrees F),
only miniatures are recommended, because they are more heat-
tolerant and bloom in warmer weather.

LIGHT is very important for growing cymbidiums. Coming from
cool and bright areas in Asia, they need high light but cool
temperatures. In many of our climates, the high level of light
cymbidiums need is accompanied by high temperatures in the
summer, which may cause the plants not to bloom. There are
several ways to counteract this: spray the plants with water
during summer afternoons to cool the plants down, shade more
heavily and increase air movement. The maximum amount of light
possible, short of burning, should be given to the plants. This
means only light shade during the middle of the day, or about
20% shade. In cool areas (e.g., coastal California), full sun
is tolerated. Leaves should be a medium to golden green in
color, not dark green. Shade more in the winter, especially if
in bud.

TEMPERATURE is the most critical factor in blooming cymbidiums
of either type. During the summer, standard cymbidiums are
usually grown outside in semi-shade, where day temperatures
should be 75 to 85 degrees F (or more), but night temperatures
in the late summer to fall (August to October) must be 50 to 60
degrees F to initiate flower spikes. Optimum temperatures in
winter are 45 to 55 degrees F at night and 65 to 75 degrees F
during the day. When in bud, temperatures must be as constant
as possible, between 55 and 75 degrees F. Miniatures can stand
temperatures 5 to 10 degrees higher than standards and still
bloom well. Most cymbidiums can stand light frosts and survive,
but it is not recommended. Bring them inside when temperatures
dip to 40 degrees F; in mild climates they may be grown outside
year-round. A bright and cool location inside is best for
winter months.

WATER must be provided at all times to cymbidiums. As semi-
terrestrials, they need a fairly constant supply of moisture.
Since they produce all their vegetative growth during the
spring and summer months, they need the most water then. Water
heavily during the growth season, keeping the potting medium
from drying out completely, and reduce water when the
pseudobulbs are completed in late summer. Keep barely moist
during the winter.

HUMIDITY outdoors is usually sufficient during the summer
months, except in dry climates. There, evaporative cooling in a
greenhouse, or misting outside, is necessary. Keep humidity at
40%-60% during the winter, especially if plants are in bud.
Keep the air moving to prevent fungus(Botrytis) from spotting
the flowers.

FERTILIZING at the proper time will help cymbidiums bloom.
During the growth season (spring through late summer), high-
nitrogen fertilizer (like 30-10-10) is used. In late summer,
use a high-phosphorus, bloom-booster fertilizer 
(like 10-30-20), to help form bloom spikes. Fertilize at full strength
every week to two weeks. In winter, fertilize once a month.

POTTING is usually done in the spring after blooming, usually
every two years or when the potting medium decomposes. Shake
all the old potting mix off the roots, dividing the plant if
desired. Divisions of green bulbs with leaves must have 3 to 4
bulbs minimum to bloom; bulbs without leaves are considered
backbulbs, and need special care to grow (see below). Pick a
potting mix that will hold moisture well; a medium-grade fir
bark with peat moss and perlite is a common mix. Select a pot
that will allow for at least 2 to 3 years of pseudobulb growth
before crowding the pot, while planning on placing the active
growing bulb(s) of the division farthest from the side of the
pot. Spread the roots over a cone of the mix in the bottom of
the pot, and fill the pot with medium, working it among the
roots, tamping firmly. The junction of roots and pseudobulbs
should be about 1/2" to 1" below the top of the mix. Keep
shaded, drier at roots but humid, until new roots grow.

Backbulbs may be left on the division to add strength, or
removed to propagate. Take single backbulbs, and bury halfway
in a bark or peat/sand mix. Keep shaded and warm until new
growth sprouts, and pot as above. It may take up to three years
to produce a blooming-size plant from this method.

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

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