With their waxy green leaves and crisp, intricate flowers, orchids (Orchidaceae) are striking plants often coveted as ornamental house plants. When cultivating orchids, few things can be more disappointing watching buds die and drop from a healthy-looking plant. Bud blast is the term given to this frustrating condition, which may be caused by a wide range of factors.
Orchids are particular about how they are watered. Both under-watering and overwatering can result in bud blast, the former causing the orchid to withdraw moisture from the buds and the latter damaging the roots and dehydrating the plant. Watering with cold water can also shock an orchid, causing it to drop buds. The American Orchid Society notes that Cattleya orchids are particularly sensitive to overwatering. Mature orchids generally do well with a deep watering once a week with room temperature water. The potting media should dry out slightly in between waterings.
Sudden changes in temperature can result in bud death. Even something as seemingly benign as a burst of hot air from an oven or a cold draft from an air conditioner can cause dropped buds. The orchid family is large and diverse, with different species requiring different temperatures. The Phalaenopsis orchid group requires minimum nighttime temperatures of 60 degrees Fahnrenheit, handling temperatures up to 90 degrees Fahrenheit, while the Cattleya orchids require temperatures between 55 and 85 degrees Fahrenheit. Both Cattleya and Phalaenopsis orchids may be grown outdoors in U.S. Department of Agriculture plant hardiness zones 10 to 12.
All About Atmosphere
Orchids should be placed in a permanent location if possible. If you must move the plant to a new area, the Missouri Botanical Garden recommends moving the plant after it has flowered. Otherwise, you run the risk of stressing the plant and losing flower buds. Chemicals and scents in the air, such as paint fumes, gas leaks and cigarette smoke, can cause bud blast. The ethylene gas produced by ripening fruits, as well as the methane gas released from other flowering plants, can also harm flowers.
Other Causes and Concerns
Good cultural care is key to maintaining a healthy flowering orchid. Light requirements vary, though Cattleya and Phalaenopsis orchids prefer bright, indirect light indoors and shady sites outdoors. Orchids will not grow in regular potting soil, which will quickly cause root rot. A coarse, loose orchid potting medium made a material such as fir bark is usually ideal. Check orchids occasionally for insects such as scale, hard brown or soft white insects that form dense colonies on leaves and flowers. Scale insects can be removed with a cotton swab dipped in 70 percent isopropyl alcohol.
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