The flowers of orchids (Orchidaceae) last several weeks or several months, depending on the orchid species. Tropical orchids bloom in a variety of colors, ranging from white through reds, pinks, yellows and all mixtures between. An orchid needs treatment different than other types of houseplants, but encouraging an orchid's natural blooming tendencies is not difficult once it is on a basic care routine.
Container and Potting Medium
An orchid grows well in either a clay or plastic pot. A clay pot allows easier absorption of oxygen to the plant. The hole on the pot's bottom can be enlarged to ensure adequate drainage.Orchids do not thrive in garden soil and do not bloom well when planted in an ordinary houseplant potting medium. The thick, fleshy roots of an orchid attach themselves to tree bark in the plant's natural growing environment. The roots absorb nutrients from the air and bark rather than from soil. Use a commercially prepared orchid potting medium that contains chopped tree fern fiber, volcanic rock,charcoal, peat moss, fir bark or a combination of these to ensure healthy growth and blooming(ref.1).
The American Orchid Society identifies lack of sufficient light as the most frequent cause of an orchid's failure to bloom. Orchid leaves are light, grassy green with yellow undertones when they receive sufficient light. Dark-green leaves indicate the plant does not receive enough light. Cymbidium (Cymbidium spp.) variety orchids, which are hardy in U.S. Department of Agriculture zones 9 through 10 are often grown in the dappled shade of large trees.(new ref. in comments box)
An east- or south-facing window with bright filtered light provides the optimum environment for a blooming orchid. Too much direct sunlight causes burn spots on the leaves. A sheer curtain can be used to create desirable shade. Move the orchid closer to or farther from the window to manipulate the amount of light the plant receives.
Air and Water
Orchid roots must have freely circulating air with gentle flowing movement. A stagnant atmosphere discourages healthy growth and bloom development. An overhead paddle fan set on the lowest speed, an open window or a slow-moving fan across the room move air sufficiently for orchid health. A fan should be directed away from the plant.
An orchid thrives with once-a-week watering, unless it dries out sooner. A plastic pot feels lighter when its potting medium is dry than when it is wet, and a clay pot feels dry to the touch when its potting medium is dry. When watering, soak the potting medium thoroughly so water runs out the bottom of the pot. Thorough soaking flushes out salts that accumulated.
Most orchid species have their bloom cycles in late winter or spring. They grow and flower for fairly long periods of time without fertilizer but produce more blooms when fertilized regularly.Use a water-soluble or granulated type commercial fertilizer specially formulated for orchids. A balanced 20-20-20 formula is recommended by the American Orchid Society(ref.3). Mix 1/4 teaspoon to one gallon of room-temperature water. Moisten the surface and roots only, not the foliage. Allow the water to run through the potting material and out the drainage hole. (see new ref. in comments section) A feeding schedule of every two weeks during active growth phases and every four weeks during rest cycles. Reduce water after spring flowering until new growth appears.