                              Phalaenopsis

Phalaenopsis, the moth orchid,  is one of the best orchids for growing in the home, and is
also a favorite of the 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 day length.  In a greenhouse, heavy
shade must be given; 70% to 85% shade, or between 1000 to 1500 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 the leave, they must never completely dry out.  PIants 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 Ieaves.

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
morning only.  Grouping plants together raises the humidity by conserving the water that
plants transpire.  In humid climates as in greenhouses, it s imperative that the humid air be
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 (30-10-10, 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
in a well-draining mix such as fir bark, treefern, 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 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 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 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 B1 solution may be helpful in establishing plants.