Phalaenopsis the moth-orchid, is one of the best orchids for
growing in the home, and is also a favorite with greenhouse growers. Culture for
Doritis,
a related genus, and Doritaenopsis, a hybrid between the two genera, is the same as for
pure Phalaenopsis.
LIGHT 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 dull, northern winter climates, a full south exposure may be
needed. Artificial lighting is excellent. Usually four fluorescent tubes in one fixture
are placed 6" to 1' over the leaves, 12 to 16 hours a day, following natural
daylight. In a greenhouse heavy shade must be given; 70% to 85 shade, or between 1,000 to
1,500 foot- candles, is optimum. No shadow should be seen if you hold your hand one foot
above the plant's leaves.
TEMPERATURES for phalaenopsis should usually be above 60 degrees F at
night, and range between 75 and 85 degrees 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 degrees F. Night
temperatures to 55 degrees F are desirable for several weeks in the fall, in order to
initiate flower spikes. Fluctuating temperatures can cause bud drop on plants with buds
ready to open.
WATER 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 through the pot. In
the 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 ten days. Water only in the morning, so that the
leaves are dry by nightfall, to prevent rot from occurring on the leaves.
HUMIDITY is important to phalaenopsis, the recommended humidity being
between 50% and 80%. In the home, set the plants on trays of gravel, partially filled with
water so that the pots never sit in water. Mist the plants in dry climates, or during dry
weather, in the mornings only. Grouping plants together raises the humidity by conserving
the water that plants transpire. In humid climates, as in greenhouses, it is imperative
that the humid air is moving to prevent fungal or bacterial diseases. Again, leaves should
be dry as soon as possible, always by nightfall.
FERTILIZER should be applied 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 (30-10- l0, or a similar formulation) are appropriate in warm,
humid conditions. When flowering is desired a high-phosphorus fertilizer (10-30-20, or a
similar formulation) may be applied to promote blooming. Some growers apply fertilizer at
1/4 strength with every watering; this is best for warm, humid conditions. When cooler, or
under dull conditions, fertilizer should be applied once a month.
POTTING is best done in the spring, after blooming. Phalaenopsis plants
must be potted a well-draining mix, such as fir bark tree-fern, various types of stone,
sphagnum moss, or combinations of these. Potting is usually done every 1 to 3 years.
Mature plants can grow in the same pot until the potting medium starts to decompose,
usually in two years. Root rot occurs if plants are let 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 medium-grade medium. When mature, a plant may stay in
the same pot size for many years, but must have the medium changed. To repot, remove all
of 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 through the roots, so that the junction of the roots and the stem is at the top
of the medium. Keep the plant shaded and humid, but drier in the pot, for several weeks to
promote new root growth. A vitamin Bl solution may be helpful in establishing plants.
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