Oncidium Orchids

August 31, 2021

Oncidium Orchids

Oncidium orchids are found in the warm, temperate regions of the Americas from Florida to Argentina. The varieties most often sold at Sheridan Nurseries produce long, arching sprays of exquisite yellow flowers, often speckled with an assortment of colours including brown and burgundy.

All orchids can be divided into two major categories, depending on where they grow:

Epiphytes as These plants cling to trees and other plants for support. Their exposed roots receive plenty of dew/rain. Oncidiums, often known as dancing lady, are epiphytic.
Terrestrial as These orchids grow directly in soil on the forest floor and prefer evenly moist conditions.

LIGHT

Depending on the particular variety, oncidium orchids prefer full sun. As with most thicker-leaved plants, oncidiums can stand higher light levels.
Oncidiums can also be grown under artificial light. Place orchids 15–30 cm (6–12”) below four fluorescent tubes.

TEMPERATURE AND HUMIDITY

Oncidiums will thrive at 13–15°C (55–60°F) during the night and 21–29°C (70–85°F) during the day.
They will handle higher temperatures if humidity and air circulation are increased accordingly.
Humidity should be at 60%; many oncidiums require less humidity than other orchid varieties.
Place plants above moist pebbles in trays with as much ventilation as possible; this promotes rapid drying after watering and minimizes the chance of rot.

WATERING

Oncidiums have pseudobulbs that actually store water, so they require less watering than other orchid varieties.
Water oncidiums thoroughly when the top half of the potting medium has dried out. This may be every 2–10 days, depending on weather, pot size, and type of potting medium.
Be sure your oncidium has excellent drainage, as its roots don’t like to stay wet.

FERTILIZER

Fertilize regularly while plants are actively growing.
Apply Parkwood® Flower Plant Food 15-30-15 twice a month for oncidiums planted in a bark-based potting medium.

RE-POTTING

Repot oncidium orchids at least every 2 years in spring when new growth is 5–7 cm (2–3”) tall or when new roots appear.
Remove all the old mix and any dead roots.
When dividing the orchid, keep the division in clumps of 3–5 mature pseudobulbs.
Spread the roots over a cone of potting medium and fill in around the roots.
Maintain a high humidity level.
Once the new roots have penetrated the bark, resume normal watering and fertilizing.

TROUBLESHOOTING

If leaves start to lighten, the orchid is getting too much light.
Watch for mealybug and spider mites; remove the former with a cotton swab dipped in rubbing alcohol and the latter with Safer’s® Trounce or Safer’s® 3 in 1.

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