Light levels are very important to Orchids.
Inadequate light levels and the Orchids will not flower. Too much light resulting in heat buildup on the leaves will kill the chlorophyll in the leaves resulting in a white to brown ‘burn’ mark. Burn will seldom kill an Orchid but it is unsightly. If you begin to see a burn pattern move it to an area with less light.
The more northerly you live in the World the less intent is the light. In most parts of the United States noon sun without shade in July will measure around 10-11,000 foot candles. During the winter when the earth shifts and we are further from the sun, the light will be considerably less. In Florida, December noon sun will seldom exceed 5000 foot candles. All Orchids can grow in less than the recommended amount of light.
The recommendations are for the light level necessary to initiate flowering. Especially with seedlings, less light is preferred until the Orchid is flowering size.
Family Foot candles
Cattleya 3500
Dendrobiums 2500-4500
Nobile Dendrobium 6000-8000 will flower as low as 3000
Oncidiums 2000-2500
Phalaenopsis 1500 mounted Phalaenopsis 3-4000
Paphiopedilum 900
Zygopedilum 2500-3000
Vanda 8000
Grammatophyllum 3000-6000
The main reason an Orchid fails to flower is inadequate light.
Fertilizers - The Basics Potting Mediums - Water - Light - Temperature - Blooming - Repotting