sam@ahuta.UUCP (sam) (03/13/85)
ORCHIDS AS HOUSEPLANTS
Due to the increasing interest in growing orchids as
houseplants, the staff of the U.S. Botanic Garden's Orchid
Department has prepared this information sheet. We describe
here of three orchid genera: Paphiopedilum (Cypridium or
Lady-slipper Orchid), Cattleya (Corsage Orchid), and
Phalaenopsis (Moth Orchid). These three types of orchids
can be grown successfully on a sunny window sill.
Light
Each type of orchid differs in the amount of light it
requires to grow and bloom properly. Paphiopedilum and
phalaenopsis orchids require approximately 1000 foot candles
of light in summer and 1500 - 2000 foot candles during the
remainder of the year. Top achieve proper light intensity
place these plants in front of a south-facing window in
fall, winter, and spring. The window must be unobstructed.
Trees growing in from of the window, curtains which are kept
closed, and near by buildings can block out light and
prevent plants from blooming. During the summer, move
Paphiopedilum and Phalaenopsis orchids to an unobstructed
northern window to reduce light intensity and prevent
foliage burn. Alternatives to moving plants are closing
sheer curtains and partially closing Venetian blinds.
Cattleyas require considerably more light than the other two
types, 1800 - 4000 foot candles. Cattleyas usually grow
best in front of an unobstructed east or west-facing window.
A good rule of thumb is: If there is enough light to take a
clear picture indoors, in front of a window, with an
instamatic camera, there is sufficient light to grow a
Cattleya orchid.
Humidity
Paphiopedilum, Cattleya, and Phalaenopsis orchids require a
relative humidity of 40 - 60%. Most homes are not this
moist. An easy way to increase humidity is to place plants
on a water tight tray filled with small damp pebbles. Keep
the pebbles moist by filling the tray with water up to the
bottom of the top layer of pebbles. Do not fill the tray up
to the point wherer the pots are sitting in standing water.
The water will evaporate from the pebbles and moisten the
air surrounding the plants. Syringing plants also increases
humidity. Always syringe orchids on sunny days. Never
syringe plants directly at close range. Instead, spray the
area around plants so that a fine mist settles on the
foliage. To help prevent disease, spray plants early in the
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day so that moisture will evaporate by evening.
Growing Medium
Orchids have been successfully grown in many potting
materials. Each grow must find the medium which gives the
best results under his or her conditions. A packaged fir
bark mix makes an excellent growing medium and is easy to
use because nothing needs to be added to it. To make up
your own fir bark mix combine 7 parts medium grade fir bark,
1 part shredded redwood, and 1 part perlite. Many orchid
growers have great success growing plants in tree fern fiber
with peat moss an perlite added to it. Unfortunately, most
garden centers do not sell fir bark or tree fern fiber.
Contact stores in your area which specialize in orchids.
They usually carry these products or will be able to tell
you where they can be purchased.
Water
When watering orchids soak the potting material thoroughly.
Do not water again until the medium feels dry to the touch.
The medium should not be constantly soaked not should it be
allowed to dry completely. It is best to water orchids in
the morning using tepid water. Slightly reduce the amount
of water given to Paphiopedilum and Phalaenopsis orchids
during their flowering cut back on watering Cattleyas when
new leaves reach the size of mature leaves. Water Cattleyas
as directed above when new growth appears again.
Fertilizer
Orchids growing in a fir bark mix should be fertilized with
a water soluble chemical fertilizer labelled 30:10:10.
Apply fertilizer at the strength recommended on the label
once a month or at half strength every two weeks. Orchids
growing in tree fern fiber should be fertilized monthly with
a balanced water soluble chemical fertilizer.
Repotting
It is necessary to repot orchids when the plant itself, not
just the roots, starts growing over the edge of the pot.
With Cattleya and Phalaenopsis orchids, do not repot until
new roots appear. If it is necessary to repot
Paphiopedilums, wait until right after they flower. The new
pot should be large enought to accommodate 2 years growth.
To repot tab the plant out of the old pot and remove the old
growing medium from around the roots. Trim off any dead
roots with a clean knife. Divide the plant, if needed.
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Position the plant in the pot and fill in around the roots
with the potting material. Firm the medium well around the
roots with your fingers or by firmly tapping the pot against
a sturdy table. Water newly potted plants immediately after
repotting. Orchids may require staking to be held upright.
Propagation
Cattleya, Phalaenopsis, and Paphiopedilum orchids are
propagated by division. Cattleya orchids are divided by
severing the rhizome (the large underground stem) with a
knife at the point where the cut will leave 3 or 4 stems per
division. When dividing Paphiopedilums, be sure there are 2
or 3 stems per division. Phalaenopsis orchids are divided
by cutting off the tip of the plant just below the new
aerial roots. Leave the bottom part of the Phalaenopsis in
the pot to continue growing. Newly divided orchids can be
potted the same way as described above.
Temperature
There is a difference in the optimum temperatures for
growing Paphiopedilum, Cattleya, and Phalaenopsis orchids.
However, all 3 will do well when the temperature during the
day is between 65 and 75 degrees F. A 5 - 10 degree drop
in temperature at night is very beneficial. If plants are
grown near a window, they will experience this temperature
change due to the loss of heat through glass.
Pests and Diseases
Orchids are subject to several pests and diseases. The best
practice is to try and prevent infestation and infection
altogether. Use sterilized pots and knives. Wash plants
regularly with tepid water. Inspect often for signs and
symptoms of pests and diseases. Purchase plants from a
reputable dealer.
Paphiopedilum, Cattleya, and Phalaenopsis orchids which are
cared for properly will bloom every year.
plant culture sheet 01b Written: 6/76
Prepared by the U.S. Botanic Garden Staff Updated: 7/79
The above reproduced without permission (but apparently
without any violation of copyright) from literature obtained
free of charge at the US Botanical Garden, Washington DC.
Doug Lewan
(...!ihnp4!)ahuta!sam
"And the bug-eyed monster?"
"It's green, yes."