Light Requirements by Genus
Looking at your plants label, determine what its genus isthat is the first name on the tag. How much light your plant will require will depend on the type of orchid it is. Below find light requirements recommended by the American Orchid Society:
Cattleya --Medium to High
Cymbidium --Medium to High
Dendrobium --Medium to High
Masdevallia --Low to Medium
Oncidium --Medium to High
Paphiopedilum --Low to Medium
Phalaenopsis --Low to Medium
Vanda --Medium to High
Low Light = 1,000 2,000 foot-candles, two hours of filtered sunlight per day, 14 hours of fluorescent light within 8 inches of the tubes. These plants can be grown indoors under indirect light or outdoors under shade.
Medium Light = 2,000 3,000 foot-candles, four hours of sunlight per day, 16 hours of fluorescent light within 6 inches of the tubes. Outside, moderately sunny windows or under lights would be suitable.
High Light = 3,000 4,000 foot-candles, six hours of sunlight per day, within 3 inches of tubes, near the center of the fixture. In a sunny window or outdoors would be ideal for these plants.
Foot-candles is a standard measure of light for plants and can be determined with alight meter.
Source: Your First Orchid, AOS, Stephen R. Batchelor