Stony Brook Orchids
Growers of Phalaenopsis Orchids

Growing Phalaenopsis Orchids

These recommendations were adapted from guidelines produced by the American Orchid Society.

Phalaenopsis , the moth orchid, is one of the best orchids for the home orchid grower.  Average home conditions are sufficient for growing and reblooming Phalaenopsis Well grown plants flower often, sometimes throughout the year. Extra flowers on certain hybrids can be obtained by cutting back the tip of the bloom spike after the initial flowering ends. However, only vigorous, healthy plants should be forced to reflower. Culture for Doritis, a related genus, and Doritaenopsis, a hybrid between the two genera, is the same as for pure Phalaenopsis.

There are five key factors to success in orchid growing:

Light is easy to provide for Phalaenopsis. They grow well in a bright windows. An east window is ideal; west or shaded south windows also work well. In dull, northern winter climates, a full southern exposure may be needed. Artificial lighting is another excellent way of providing light. Sufficient light is provided by four fluorescent tubes in one fixture, placed 6 to 12 inches above the leaves. Artificial light should be provided 12 to 16 hours a day, following natural daylength. In a greenhouse too much light may be present, and shade must be provided. In our area we use 70% to 86% shade, providing between 1,000 to 1,500 foot-candles of light to the plants.

Temperatures for Phalaenopsis should usually be above 60oF at night, and between 75oF and 85o F or more during the day. The recommended maximum temperature is 95oF. Although higher temperatures force faster vegetative growth, high humidity and air movement must accompany higher temperatures, otherwise the plants may suffer. Nighttime low temperatures around 58oF are desirable for several weeks in the fall, since cool evenings will aid flower spike initiation. Fluctuating temperatures can cause bud drop on plants with buds that are ready to open.

Water is especially critical for Phalaenopsis . Because they have no water storage organs other than their leaves, Phalaenopsis must never completely dry out. Watering frequency is a function of the medium in which the plants are grown. At Stony Brook Orchids we grow our Phalaenopsis in a peat-based mixture. By checking the top inch of the peat mixture it is easy to tell when a plant needs watering. When the top inch is dry, the plants are ready for watering. Plants should be evenly watered, and not watered again until the top inch of the soil medium is dry. To prevent diseases from occurring, water only in the morning so that the leaves are dry by nightfall.

Humidity is important to Phalaenopsis, and we recommend a relative humidity between 50% and 80%. In the home, set the plants on moisture (or gravel) trays partially filled with water. Make sure that the pots are not sitting directly in the water.  Grouping plants together can also be helpful. Grouping raises the local humidity by taking advantage of the water that plants transpire. Humidity levels below 50% can result in the premature loss of buds and flowers. In very humid conditions, as in some greenhouses, it is imperative to keep the humid air moving to prevent fungal and bacterial diseases. Leaves should be kept as dry as possible, especially at night.

Fertilizer should be applied on a regular schedule, especially if the weather is warm, when the plants are most actively growing. Make a solution by mixing 1/4 teaspoon of any good houseplant fertilizer (i.e., 20-10-20, 20-20-20, 7-9-5 formulations) with one gallon of water. Use this weak fertilizer solution every time that you water. In winter fertilize less often, once every two weeks or once a month.

Phalaenopsis orchids are best repotted in the spring after they have finished blooming. Phalaenopsis must be potted in a well-draining mix. For best results repot annually. A mature plant may remain in the same size pot for years, but for best growth the medium should be changed annually. To repot, remove all of the old medium from the roots, trim away any soft, rotted or broken roots. 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. A drench with vitamin B1 solution may be helpful in establishing newly repotted plants.