Phalaenopsis and Paphiopedilum species; easy orchids to grow as houseplants
It's not necessary to turn your home into a steaming jungle in order to grow beautiful orchids. In fact, many orchids really don't deserve their reputation for being difficult or fussy plants to grow.
Among the easiest to care for as houseplants are species and named cultivars of Phalaenopsis (known as moth orchids) and Paphiopedilum (known as ladyslippers - though they're not the ladyslippers that grow outdoors in Minnesota).
Photo: Deb Brown
Photo: Deb Brown
Both Phalaenopsis and Paphiopedilum orchids are known for their long-lasting flowers. Individual moth orchid blossoms may remain open and fresh for two months or more.
Phalaenopsis orchids are epiphytes, which means in nature they grow in the branches of tropical trees, clinging to them for support while absorbing moisture from the surface of bark that is wet from dew and from rainfall. This means they should be potted in special orchid mix made of bark chunks that won't absorb much moisture. They will not tolerate soggy roots, so when you water, that water should whoosh right through the potting medium.
Paphiopedilum orchids are terrestrials or soil-dwellers. They should be potted in a more typical houseplant mix that holds some moisture but still drains well. Neither type of orchid should need repotting for at least a year after they're purchased.
Humidity - While neither Phalaenopsis nor Paphiopedilum orchids need extremely high humidity, they do benefit from added humidity in winter. Placing pots on top of gravel in moisture-filled trays might help. You just need to be careful that their pots are set above the water line so no moisture will be drawn in through bottom drain holes. Room humidifiers also help increase relative humidity without jeopardizing orchid roots.
Watering - Neither of these orchids should be allowed to dry out completely between waterings. How often you water will depend on how bright their growing conditions, how humid, and how warm it is, all factors that impact how fast the potting mix will dry. Always use room temperature or barely lukewarm water that will not shock the orchids' roots, and avoid softened water if at all possible.
Make a point of holding the container over a sink or washtub and watering thoroughly so moisture drips right through and is discarded. Lift the pot right after you've watered to get a feeling for its weight, then hold off watering again until it feels lighter. Don't rely on the calendar to tell you when to water.
Fertilizing - Use a special orchid fertilizer such as 30-10-10, mixed half-strength, once a month - more often during growth spurts in spring and summer. Every three months fertilize them with a complete fertilizer containing minor elements along with the major elements, nitrogen, phosphorus, and potassium. Almost any ratio of the major elements in this complete fertilizer is acceptable.
Light and temperature - All orchids need good light, but they cannot stand much of the heat which usually accompanies high light intensities. You may reduce temperatures in south or west-facing summer windows by drawing sheer curtains across them.
If daytime temperatures exceed 90 degrees, you'll have to move the plants to a cooler window such as an east-facing exposure. It's doubtful whether orchids would bloom in a north window.
Many people grow their orchids successfully under fluorescent tubes. Place them so the lights are about eight inches above the orchids' foliage, and keep the lights on from twelve to fourteen hours daily.
Orchids may fail to bloom if night temperatures are very close to daytime levels. A two-week period in spring or fall where temperatures at night are kept ten to fifteen degrees cooler than during the day should initiate flower development, assuming the plant receives adequate light levels.
Problems - Besides failing to bloom when night temperatures are too high, Phalaenopsis and Paphiopedilum orchids will not bloom if light levels are too low or too high. Low light is often accompanied by the presence of dark green foliage. Too much light may result in leaves that are pale yellow-green and bleached looking.
Orchids may also fall prey to common houseplant insect pests such as mealy bugs, scale, and spider mites. If your plants have a problem that doesn't respond to washing or wiping with an alcohol dipped cotton swab, check your local garden center for houseplant pesticides that are labeled for use on orchids. Be sure the plants are not moisture-stressed when you treat them, and keep them out of direct sunlight for two or three days afterwards.
Much of the information for this Brief was taken from Horticulture Fact Sheet #46, 1977: Orchids for the Home Environment, by Steven J. Murray and Deborah L. Brown.