Care of Oncidium Orchids

Plant Oncidium orchids in small pots with fir tree bark, perlite, charcoal, tree fern or volcanic rock as soil. In the wild, they are epiphytes, which means they attach themselves to other plants to grow. They usually attach themselves to trees, and in your home, they need potting materials that mimic that growing environment.

Place orchids in windows facing south or west, where they'll receive plenty of light. Because Oncidium orchids require more light than most other orchids, make sure they receive some direct sunlight each day. A bathroom window is a smart choice to keep humidity levels high---a necessity for orchids.

Keep orchids in regular household temperatures. Typically, 65 to 80 degrees Fahrenheit is comfortable for daytime, though Oncidium orchids like even warmer temperatures---in the 80's---whenever possible. Let the temperature drop at least 10 degrees Fahrenheit each night to inspire flowering. Don't let temperatures drop below 55 degrees Fahrenheit if possible, as they need warm weather for survival.

Maintain humidity of 30 to 60 percent. If orchids are not in a bathroom window, a humidifier helps increase humidity. The University of Tennessee article "Growing Orchids in the Home" recommends growing orchids in plastic pots sitting in trays filled with gravel. Placing them close together in the trays and adding water to the gravel increases humidity for the orchids.

Water once a week when the soil becomes completely dry. Let the water drain thoroughly. Because Oncidium orchids have water storage in their leaves, they are drought-tolerant and prefer thorough, infrequent waterings that mimic the occasional bursts of rainfall they would receive in the wild.

Fertilize once a week with a dilute fertilizer while the orchids are growing; stop when orchids enter a dormant period. If planted in bark, they need a nitrogen-rich soil, such as that found in 30-10-10 or 15-5-5 fertilizers. The first number refers to the nitrogen content, while the others refer to phosphorus and nitrogen. An equal ratio---such as 20-20-20---is sufficient for orchids planted in materials besides bark.