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Careful selection of orchids guarantees success as houseplants
Saturday, March 10, 2001 By Georgia Wahl, Phipps Conservatory and Botanical Gardens
This is one of a series of periodic columns by staffers of Phipps Conservatory and Botanical Gardens. Georgia Wahl is Phipps' orchid grower.
Orchids are the largest family of flowering plants, with more than 30,000 individual species, and they are the most highly evolved.
Although orchids have a reputation for being difficult to grow, they are actually fairly simple if you choose ones that will grow well in your home. Some orchids need high light and others prefer low light. Some require warm temperatures while others prefer a cooler environment.
Temperature, the amount of light and the frequency of watering are the key factors in growing orchids. Here are a few general guidelines to help you get started:
Orchids that prefer warm temperatures should be grown in areas reaching 70 to 85 degrees during the day, with nights no cooler than 65 degrees. Orchids that grow in intermediate or temperate temperatures need between 65 and 75 degrees during the day and 55 to 65 degrees at night. Cool-temperature orchids prefer no lower than 50 degrees at night and days should not exceed 75 to 77 degrees.
Plants that grow best in warm temperatures include phalaenopsis (moth orchids), paphiopedilums (lady's slipper orchids), vanda and ascocenda orchids. Intermediate growers include the cattleya, oncidium and some dendrobium orchids. In the cool growing category are the cymbidiums, some dendrobiums and many miniature orchids.
Orchids are also grouped by how much light they need. Those requiring the greatest amount of light include cymbidiums, vandas and cattleyas. A south- or west-facing window is best for these plants. Phalaenopsis, dendrobiums and oncidiums grow best in intermediate light. Paphiopedilums prefer lower light.
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This is one of a series of periodic columns by staffers of Phipps Conservatory and Botanical Gardens. Claire Dusak is the outdoor garden manager at Phipps, and Miranda Sutton is Phipps' communications coordinator.
Orchids can also be grown successfully under artificial lights. Use a combination of five watts of fluorescent to every one watt of incandescent, with a minimum of four bulbs. The plants need at least 14 hours of light a day and may take a few months to adjust to the artificial light.
Plants requiring high light should be placed only 3 inches from the lights. Low-light plants should be 12 inches away. It is a good idea to change your bulbs yearly to ensure maximum brightness.
Watering orchids is a rather complex task, as different types of orchids have different needs for moisture. For example, phalaenopsis like to dry out slightly between waterings while paphiopedilums should never dry out completely. Vandas need to be watered daily, but cattleyas, dendrobiums and oncidiums like to dry down to at least a 1-inch depth of the bark they are potted in. Cymbidiums prefer to stay fairly moist.
When watering, it is a good idea to water copiously to ensure thoroughly wetting the bark and roots. Be sure that the plant is not allowed to sit in any of the run-off water. Watering frequency should be cut back in winter, especially during multiple gray days.
Orchids are generally grown in bark to ensure good drainage. Different types of bark are used to accommodate orchids' varied watering needs. Fine or seedling bark is used for orchids that like a lot of moisture; medium-grade bark is best for ones that like to dry out more.
Repotting is done every one to two years, depending on how much the bark has broken down. As the bark breaks down, it begins to hold too much moisture at the orchid's roots. Bark used with orchids that are watered more frequently tends to break down faster.
Fertilizing can be done with any balanced fertilizer such as 20-20-20 or 18-18-18. A good slogan to remember is to "fertilize weakly, weekly." In other words, it is better to use half-strength weekly than full strength more often.
Orchids are beautiful blooms that can add graceful elegance and color to your home. If you follow the above guidelines, an orchid paradise will soon be yours.
If you'd like more information about orchids, visit the Orchid Show at Phipps Garden Center from March 21-25.
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