Phaleanopsis, the Moth Orchid, is one of the best orchids for growing in the home, and is also a favorite with glasshouse growers. Culture for Doritis, a related genus, and Doritaenopsis, a hybrid between the two genera is the same as for pure Phalaenopsis.
Temperatures: for Phalaenopsis should usually be above 15°C at night, and range between 24-29°C 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 32-35°C. Night temperatures to 12°C are desirable for several weeks in autumn, in order to initiate flower spikes. Fluctuating temperatures can cause bud drop on plants with buds ready to open.
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 north or west windows are acceptable. In dull, southern winter climates, a full northern exposure may be needed. Artificial lighting is excellent. Usually four fluorescent tubes in one fixture are placed 150 - 300mm over the leaves, 12 -16 hours a day, following natural day length. In a glasshouse heavy shade must be given; 70% to 85% shade, or between 1000-1500 foot candles, is optimum. No shadow should be seen if you hold your hand one foot over the plants leaves.
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 southern glasshouse, 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 betwen 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 glasshouses, it is imperative that the humid air is moving to prevent fungal or bacterial disease. Again, leaves should be dry as soon as possible, allways 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 (10-30-10, 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, tree fern, various types of stone, spagnum moss, or a combination of these. Potting is usually done every 1-3 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 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 handfull 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 B-1 solution may be helpful in establishing plants.