Oncidium
on-SID-ee-um

The dancing ladies

Oncidiums are fast growing as a popular orchid from the high Andes, due to their wide diversity of shapes, colors, and number of flowers. They have been bred with a wide variety of other species like odontoglossums, aspasia, brassias, and miltonias to form intergenarics. Thus, their culture varies by their breeding line to cool intermediate or warm. This makes cultural generalizations difficult. Like most other cultivated orchids, Oncidiums are epiphytes, or air plants. They have well-developed water-storage organs (called pseudobulbs) and large, fleshy roots. They should be potted in a porous, free-draining medium. The most commonly used are mixes (in the north) with fir bark or coconut chips, sphagnum moss, and peat moss as the base with charcoal, perlite and other materials sometimes used as additives. Keep out of cold, dry air while in bloom.

L I G H T

Sufficient light is important for healthy growth and flower production.

PROVIDE Bright light, some sun. In the home, an east, west or lightly shaded south window. In a greenhouse, about 40 to 70 percent full sun should be provided. While, under lights, four 40 watt fluorescent tubes and two 40 watt incandescent bulbs directly over plants. Plants should be naturally erect, without need of much staking (flowers still may require staking), and of a medium olive-green color. Dark green, limp foliage indicates too little light.

TEMPERATURE

Mature plants prefer a 15 to 20 F difference between night and day.

PROVIDE Nights of 40-60F for cool 50 to 60 F for intermediate and 55 to 70F for warm : days of 65 to 85F for cool and intermediate . Warm growing can tolerate temperatures up to 95 to l00F if shading, humidity and air circulation are increased. Cool growing will die in temperatures above 90 in just a couple of days. Seedling oncidiums prefer temperatures 65-80 F. continuously..

W AT E R

Mature plants must dry out between waterings. In the house with a few plants a soak watering by placing in a bucket of water to mix level can be used to provide a good watering. In the greenhouse water heavy and then let dry out. Seedlings need more-constant moisture. Quality of water is important to keep salts low.

H U M I D IT Y

Oncidiums prefer 40 to 70 percent. In the home, place on humidity trays. In greenhouse, use a humidifier if conditions are too dry. Misting plants in the morning only is also good. If these plants stay too dry the leaves will wrinkle into an accordian shape.

FERTILIZER

Must be provided on a regular basis because most potting media have little.

PROVIDE The exact fertilizer you use will depend on the mix in which your plant is growing. A good general rule is to use a balanced fertilizer "weakly, weekly." That is, fertilize every week at one half teaspoon/gal. A nitrate based form of nitrogen is best.

POTTING

Should be done every two years for mature plants, every year for seedlings and plants in fine mix. Repot in spring before mix loses consistency (breaks down). Pot firmly in media that has good aeration and ample drainage, allowing enough room for two years' growth. Some types like equitant and mule-ear oncidiums can also be mounted on cork or other special material to make a more natural look but watering must be increased .

SUMMER OUTINGS

Hanging plants out for the summer in a lightly shaded area can be of great benefit for those growing in the home. Watering and other requirements go down, easing summer care. Just bring them in before it gets too cold and treat for pests on plants when you bring them in.

Roberts Flower Supply 12390 Root Rd Columbia Station Ohio 44028 440-236-5571