How to Care for Oncidiums

Pot oncidium orchids in a well-drained mix of commercial orchid medium or make your own by combining 1 part perlite, 1 part sphagnum peat moss and 6 parts pine bark that has 1/4- to 1/2-inch chunks.

Place planted pots in an area that has bright, indirect light. An east-, south- or west-facing window is suitable as long as the plants are not in direct sunlight. Oncidium varieties with thick leaves require more sun than those with thin leaves. Place plants outside in partial shade during summer.

Keep temperatures warm at 70 to 85 degrees Fahrenheit during the day and no lower than 55 F at night. Temperatures of 90 and above are tolerated as long as there is a good deal of humidity and good air circulation around the plant.

Pour pebbles into a tray and fill with enough water to stay under the top of the pebbles. Place orchid pots on top of the tray. This provide the needed humidity for the plant. Keep water at a level where it will not seep in through the drain hole of the pot.

Water to keep the planting medium evenly moist while the plant is blooming. Let it dry out a day or two before watering when it is dormant.

Fertilize oncidium orchids with a water-soluble orchid fertilizer that is high in nitrogen. Use it every two weeks to once a month for six months after the first bloom. Fertilize once a month with a low-nitrogen fertilizer the next six months while the plant is in dormancy.

Cut flower spikes at the base after all flowers die back.