Answer: In general, provide bright, indirect light to orchids. Full sun can scorch their leaves. Fertilize lightly during the growing season and keep the root evenly moist, but not too damp. Keep your orchid in a cool place (60F) and see how it does. It's easy to provide the local humidity an orchid needs by placing the pot on a tray of stones. Keep water in the tray, but don't let it reach the level of the pot. As the water evaporates it will humidify the air around the leaves.
If you want even more details on oncidiums, take a look at this website: http://www.pathfinder.com/vg/TimeLife/Houseplants/Flowering
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