Give orchids bright light, but no direct sun.
Insufficient light is one the chief causes of orchids failing to bloom. Different kinds of orchids need different levels of light. If an orchid’s leaves are light green, it is probably receiving enough light to bloom. Dark green leaves may indicate that the plant needs brighter light.
Some kinds, such as Phalaenopsis and Paphiopedilum, can do well under artificial lights. Flourescent lights work well, and are energy efficient. Keep the lights 6-8 in/15-20 cm above the plants, but check that the bulbs do not burn leaves.
Some orchids require bright light, but no direct sun. Orchids such as Phalaenopsis and Paphiopedilum live as epiphytes in lower parts of the forest. Trees and clouds block the direct rays of the sun. Direct sun can cause sunburn on the leaves, leaving large dead spots. Give these bright shade instead.
Many orchids can handle some direct sun. Morning sun is usually best; most need protection from direct midday sun and hot afternoon sun. These include Cattleyas, Dendrobiums, Laelias, and Oncidiums.
Orchids that grow at the tops of trees and in other exposed conditions can handle full sun. These include Vandas and some Epidendrums.
In wintertime when the sun is lower in the sky, many orchids can handle brighter light. Be sure to move them back into more shade in springtime.
Plants moved into brighter light need a few weeks of adjustment so that their leaves do not sunburn. Gradually introduce the plant to brighter light, and make sure it receives adequate water and humidity.