Temperature: 60°F-64°F at night. 70°F-85°F during the day. In summer add a few degrees to these temperatures. Cooler temperature at night will encourage spike production.
Light: Bright light in an east or west window. If using south facing window, a sheer curtain will help diffuse the light.
Water: When moss or bark just begins to feel dry to the touch, water thoroughly, allowing water to run through. Let plant drain completely before returning to a saucer, never allowing plant to sit in water. Do not use water that has been softened by addition of salts. In fact, oncidiums prefer distilled or rainwater. Thoroughly flush with clear water once a month to prevent salt buildup.
Humidity: Normal, but not overly dry. About 40% is good.
Fertilization: Use an orchid food such as Better-gro, a urea free food with nitrate nitrogen, feeding at every watering or every other.
Growing Medium: Oncidiums like a fine or medium orchid bark mix. Do not crowd the plant as it likes adequate air movement.