Phalaenopsis, the moth orchid,
is perhaps the best orchid for growing in the
home, and is also a favorite with greenhouse
growers. Well-grown plants can flower often,
sometimes with a few flowers throughout the year,
though the main season is late winter into
spring. Average home temperatures and conditions
are usually sufficient. Flower stems on certain
hybrids can be forced to rebloom by cutting the
tip off after the initial flowering. Only healthy
plants should be induced to flower repeatedly.
Culture for Doritis, a related genus, thought by
some to be conspecific with Phalaenopsis, and
Doritaenopsis, a hybrid between the two genera,
is the same as for pure Phalaenopsis.
L I G H T is
easy to provide for phalaenopsis. They grow
easily in a bright window, with little or no sun.
An east window is ideal in the home; shaded south
or west windows are acceptable. In overcast,
northern winter climates, a full south exposure
may be needed. Artificial lighting can easily be
provided. Four fluorescent tubes in one fixture
supplemented by incandescent bulbs are placed 6
to 12 inches above the leaves, 12 to 16 hours a
day, following natural day length. In a
greenhouse, shade must be given; 70 to 85 percent
shade, or between 1,000 and 1,500 foot-candles,
is recommended. No shadow should be seen if you
hold your hand one foot above a plant's leaves.
T E M P E R AT U R E S
for phalaenopsis should usually be above 60 F at
night, and range between 75 and 85 F or more
during the day. Although higher temperatures
force faster vegetative growth, higher humidity
and air movement must accompany higher
temperatures, the recommended maximum being 90 to
95 E Night temperatures to 55F are desirable for
several weeks in the autumn to initiate flower
spikes. Fluctuating temperatures can cause bud
drop on plants with buds ready to open.
W A T E R is
especially critical for phalaenopsis. Because
they have no major water-storage organs other
than their leaves, they must never completely dry
out. Plants should be thoroughly watered and not
watered again until nearly dry. In heat of summer
in a dry climate, this may. be every other day;
in the winter in a cool northern greenhouse, it
may be every 10 days. Water only in the morning,
so that the leaves dry by nightfall, to prevent
rot.
H U M I D I T Y
is important to phalaenopsis, the recommended
humidity being between 50 and 80 percent. In
humid climates, as in greenhouses, it is
imperative that the humid air is moving. Leaves
should be dry as soon as possible, always by
nightfall. In the home, set the plants on trays
of gravel, partially filled with water, so that
the pots never sit in water.
F E R I T I L I Z E on
a regular schedule, especially if the weather is
warm, when the plants are most often growing.
Twice-a-month applications of high-nitrogen
fertilizer (such as 30-10-10) are appropriate
where bark-based media are used. Otherwise, a
balanced fertilizer is best. When flowering is
desired, a high-phosphorus fertilizer (such as
10-30-20) can be applied to promote blooming.
Some growers apply fertilizer at one-quarter
strength with every watering; this is best for
warm, humid conditions. When cooler, or under
overcast conditions, fertilizer should be applied
twice per month at weak strength.
P O T T I N G
is best done in the spring, immediately after
flowering. Phalaenopsis plants must be potted in
a porous mix. Potting is usually done every one
to three years. Mature plants can grow in the
same container until the potting medium starts to
decompose, usually in two years. Root rot occurs
if plants are left in a soggy medium. Seedlings
usually grow fast enough to need repotting
yearly, and should be repotted in a fine-grade
medium. Mature plants are potted in a
medium-grade mix. To repot, remove all the old
medium from the roots, trim soft, rotted roots,
and spread the remaining roots over a handful of
medium in the bottom of a new pot. Fill the rest
of the pot with medium, working it among the
roots, so that the junction of the roots and the
stem is at the top of the medium.
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Prepared by the AOS Education Committee