Orchids have always had the reputation of being exotic plants, unsuited to home conditions. For many of the more than 35,000 orchid species that exist this is true. However, there are orchids that can be grown successfully under the conditions that exist in the average home.
Among the two orchid genera most grown in homes are hybrids of the Cattleya genus and hybrids of the Phalaenopsis genus. Flowers of both genera have found frequent use in corsages and wedding bouquets. Cattleya hybrids produce fairly spectacular large flowers in colors that include white, orchid, purple, red, yellow or many shades and combinations of these colors. Cattleya flowers have two large horizontal petals and a lower petal called a ‘lip’. Between these are three smaller sepals. Cattleya hybrid plants have leaves that are stiff and upright with a storage structure at their base called a pseudobulb. Their growth is sympodial, which means that a new shoot arises from the base of the rhizome of the previous growth.
In contrast, phalaenopsis have a monopidial growth in which a compact central stem exists which grows upright each year from a central stem and which does not contain any storage structure. Phalaenopsis is native to tropical Asian jungles where there is sufficient rain and humidity so plants do not need any water-storing structures. The flowers of phalaenopsis are distinct. They are fairly flat, usually smaller than most cattleyas, and primarily in white and pink shades although the color range is increasing. They produce abundant flowers on long, graceful stems while cattleyas produce fewer but larger flowers on short, stiff stems.
Both these types of orchid are epiphytic which means that they derive their natural nourishment from air, rain, and organic debris around them. In pots they are usually grown in bark, osmunda fiber or a number of organic mixes. The growing media of these orchids must remain fairly loose and airy. If it decomposes to a point where it becomes too dense, roots will suffocate and plants weaken. Repotting is necessary whenever the media begins to collapse and growth begins to weaken. This may be about every two to three years in the average home.
Plenty of light, but not too much, is also important. Cattleyas need light between 2,000 and 4,000 foot candles. Phalaenopsis need less and should be maintained between 1,000 and 1,500 footcandles. In both cases direct sunlight should be avoided as it can cause leaf burn which turns leaves black. If plants are grown in a window with direct sunlight at any time except in the very early morning or very late afternoon, a sheer curtain should exist between the plants and the sun. In winter, when outdoor light is low and days are short, artificial fluorescent light may be added to increase day lengths to about 12 to 14 hours.
Watering is very important to both genera, but particularly for phalaenopsis since they have no storage mechanism. Plants will dry out in 5 to 7 days, so a thorough drenching is best weekly. For cattleyas this might be extended to biweekly with light watering between. This drenching means placing each pot in a tub of water up to the rim for a minute or two to allow the medium to become thoroughly wetted. An orchid fertilizer may be added at the time of the soaking, about monthly when plants are not growing actively and biweekly when plants are in active growth.
Phalaenopsis need day temperatures near 75 degrees F and 65 degrees at night. Cattleyas can be grown slightly cooler, with day temperatures usually best close to 70 degrees and night temperatures close to 60 degrees. Slightly higher day temperatures are not as critical as proper night temperatures. Humidity of 60 to 70% during the day and 40 to 50% at night are best. This can be done by setting plants on gravel with water below it or misting over plants daily, particularly on the exposed aerial roots. The higher the temperature, the more critical higher humidity and misting become for good growth and flowering.
Growing orchids indoors is possible by putting them in an east-facing window, watering them with lukewarm water and wiping the leaves dry with a clean cloth. Grow orchids inside the house, never throwing away a plant once the blossoms die.