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Many
orchids are rewarding indoor plants. Once a home owner
has succumbed and bought his or her first orchid, or
received one as a gift, meeting a few cultural requirements
will coax the plant to flower again.
Orchids
are far tougher and hardier than most people think,
and are, by and large, extremely adaptable. There
is a long-standing myth that orchids are difficult,
if not impossible, to grow, especially without
a greenhouse. With at least 20,000 species and
some 100,000 artificial hybrids, there are some
notoriously fussy orchids. But there are many rugged,
popular, easy-to-grow types that adapt to the temperatures
and light conditions found on the average home
windowsill. Explore the options and assemble a
collection that will put forth exotic flowers year-round.
Orchids are different from other houseplants. Unlike
ferns, philodendrons, palms and Swedish ivy, orchids
do not grow in soil. Potting an orchid in soil is
actually one of the best ways to kill it. Most orchids
in the wild are not rooted in the ground, but instead
attach themselves by thick roots to the sides of
trees and on branches. Clinging to the bark, the
plants absorb water and nutrients from the air and
rain and whatever drips down the tree. They are adapted
to surviving when rain is scarce, hoarding water
in thick leaves, stems and roots.
Watering
In the house, orchids are grown in pots filled with chips of bark, stones,
treefern or some other loosely packed material, which keeps roots well-aerated
and permits water to drain quickly. Nothing — repeat, nothing — kills
an orchid faster than letting it sit in a water-logged pot, since a
lack of oxygen will cause the roots to suffocate and rot.
Water orchids thoroughly, usually about once a week,
then allow them to dry slightly before watering again.
Orchids are better equipped to withstand periods
of forgetfulness than they are to being over watered.
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Temperature
Another difference between orchids and many houseplants is that in nature
most orchids experience a big difference between day and night temperatures.
Manipulating the temperature of the home so it will drop at least 10
degrees at night, especially in autumn and winter when many orchids
initiate buds, will induce the orchids to set flower buds more readily.
Achieve this by lowering the temperature on the thermostat. This little
trick can mean the difference between an orchid plant that merely lives,
and one that thrives and flowers.
Orchids are usually classified as warm growing, intermediate
and cool growing, with regard to their temperature
needs. Many tolerate exposure to warmer or cooler temperatures
without suffering damage. The temperature groupings
refer to the lowest temperature the orchid prefers
during winter nights. Warm-growing orchids, such as
phalaenopsis, sulk if temperatures drop much below
60 F. Intermediate growers, such as cattleyas, prefer
winter nights around 55 F. Cool-growing orchids, including
cymbidiums and odontoglossums, are accustomed to winter
nights of 50 F. At the other extreme, most orchids
perform poorly when exposed to temperatures above 90
F.
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Light
Orchids are also classified into three other groups depending on the
intensity of light they require -- high (3,000 foot-candles), medium
(2,000 foot-candles) and low (1,000 to 1,500 foot-candles). Most orchids
require plenty of light, preferably at least six hours a day. Many
orchids can withstand more or less than the amount of recommended light,
but providing more light enhances flowering potential. Conversely,
inadequate light prevents orchids from flowering, although they will
grow.
Leaf color indicates if the amount of light is adequate.
The lush, rich, dark green of most houseplants is
not desirable in orchid leaves. Dark green leaves
are attractive, but signal there is not enough light.
A grassy green color (light or medium green with
yellowish tones) means the plant is receiving sufficient
light to bloom. Gauge light intensity with this simple
hand/eye test: Put your hand 6 inches above the leaves
and look at the shadows cast. A sharp-edged shadow
means high light; a soft-edged shadow indicates medium
to low light; no shadow at all means the light is
insufficient for an orchid to flower.
Southern- and eastern-facing windows work best for
orchids; western windows can be too hot in the afternoon;
and northern ones are usually too dark. Too much
direct light causes leaves to sunburn -- the leaves
bleach out to white, ultimately dying and turning
black -- so it may be necessary to reposition plants
as the seasons change. Move plants away from or toward
the window to manipulate the amount of light. A sheer
curtain will cast light shade. Positioning sheets
of Mylar or another reflective material in the growing
area will increase usable light, a handy trick for
the winter when light levels are often reduced.
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Artificial
Light
Where windows with adequate light are unavailable, consider cultivating
orchids beneath artificial light. Four 4-foot-long fluorescent tubes
placed 6 inches apart side by side should do the trick. Two shop-light
fixtures with cool-white bulbs will suffice. Special grow lights, sold
under various trade names, are considerably more expensive and extend
the light spectrum. The grow lights may reap better results, although
data on this are conflicting. Place plants 6 to 8 inches below the tubes.
Put the lights on a timer set to operate the bulbs for 14 to 16 hours
a day. Many orchids, such as phalaenopsis and paphiopedilums, will be
content. Orchids requiring more light, such as vandas and cymbidiums,
however, need natural sunlight or high-intensity discharge lights to
bloom.
A
fluorescent fixture in a dimly lit window adds
extra light to natural sunlight, too, and can mean
the difference between flowers and no flowers.
Orchids that do not flower often require more light.
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Fertilizing
Orchids do not require abundant doses of fertilizer. However, to maintain
healthy plants and see blooms on a regular basis, apply a weak solution
of 20-20-20 fertilizer once a week. Each month, water with plain
water to flush out any accumulated fertilizer salts. Dilute the fertilizer
to one-quarter the strength recommended on the package. When in doubt,
give less rather than more.
Switch
to a blossom-booster fertilizer in the autumn,
when many orchids are initiating flower buds. Blossom-booster
is a fertilizer ratio with higher phosphorus and
lower nitrogen, such as a 10-30-20 formula. Many
orchids are winter bloomers, which makes them even
more special as houseplants. They fill an often
otherwise flowerless void in the drabbest of months.
Peak of orchid bloom usually occurs between December
and April.
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Humidity
One of the things orchids greatly appreciate is adequate humidity. Fifty
percent or more is necessary, but the atmosphere in most homes, especially
those with dry, hot-air heat, is far below that. Raising the humidity
around orchids will result in better flowering. Some tricks to increase
humidity: operate a humidifier near the plants; place the pots on
flat, black pebbles set in a tray in which water is added until it
almost covers the stones ("Egg crate," which is the lattice-like
plastic grid sold in hardware stores for suspension ceiling lights,
is a good, more steady alternative to the pebbles.); group the orchids
together; or cordon off the growing area with clear plastic (but
continue to provide ventilation to prevent bacteria from becoming
a problem).
High
humidity, however, can create a host of problems,
such as fungal diseases and bacterial infections
that mar foliage and flowers alike. Natural, healthy
orchid environments are full of breezes which counteract
these potential hazards. Sufficient air movement
is essential to keep them at bay in the home. Small
fans keep the air buoyant; switching their location
and direction every once in a while emulates natural
breezes. If the orchid-growing environment feels
and smells fresh, chances are it is meeting the
orchids' needs.
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