Oncidium Orchids

The Oncidium Alliance are a hardy group of orchids and cope well with a wide temperature range. Although many are yellow and brown flowering, a range of colours and forms are available for sale in this group. (see picture right of a golden coloured oncidium orchid)

As Oncidium Orchids originally come from a range of climates from sea level in the tropics to the high mountains of South America. They are an epiphytic orchid and best results seem to come when they are mounted on bark mounts, mimicking the natural growth habit. This method of cultivation seems to eliminate the problem of root rot which is common with pot grown specimens.

Generally speaking they are a hardy variety and will survive in less than ideal conditions. Oncidiums are sometimes referred to as ‘Dancing Girls’

The Oncidium Alliance are a hardy group of orchids and cope well with a wide temperature range. Along with this they are hybridized and have large racemes of flowers which makes them popular not only with collectors but also with florists.

Oncidium Orchid Care

Generally speaking they are an easy care and hardy variety and will survive in less than ideal conditions. Many are hybrids within the Oncidium Alliance and will include crosses with Miltonia and Ondotoglossum, some of these require slightly different care especially relating to temperature.

Bright filtered light is essential, you can usually tell by the leaf color, a nice bright green rather than deep green is what we are after. The darker green usually indicates to little light.

Try a position in a shade house where they receive good strong filtered light and good air flow. Most varieties are best grown in hanging baskets or slatted orchid baskets. Good drainage is essential so a course pine bark will work well.

During the winter months they need little watering and more light, in the warmer months, a 50% shade cloth is suitable as is more regular watering.

These are an orchid that like to go almost dry between watering, especially during winter dormancy. Increase watering and humidity as temperatures rise.

One trick is to pinch out flowers of young plants, this seems to speed up development of new plants.

The root system of a healthy plant will work its way through the potting medium, at a glance if the roots are green, then the plant is in active growth and its time to water and fertilise them.

Watch out for snails and slugs eating the roots, this can set the plant back dramatically. 

The best time to repot Oncidiums is in early spring as the move into the active growth cycle. Most varieties will flower in autumn.

Major Care Factors

1. Light.
   Good filtered light, a 20% shade cloth in winter with 60% – 80% shade in summer. The amount of shade in summer will depend on the climate.
2. Watering.
   These are plants that grow naturally in a wet dry climate. They receive moisture in the evening and morning through mist and then dry daytimes.
3. In summer you will need to water regularly, exactly how often will depend on the climate. As a rule every day during hot summers, every 2 – 3 days in cooler summers.
   During winter once a week.
4. Fertiliser.
   When repotting put a little slow release fertiliser near the bottom of the pot ( 1 good pinch 1/3 of the way up). Pot the plant and water in.
5. At other times a pinch of slow release fertiliser once a year. Use a low nitrogen, high potash type fertiliser.
6. Temperature
   Although tolerant of a wider temperature range generally a nighttime temperature of 60° – 65°F (15°C – 18°C) and daytime of 70°-85°F (21°C – 29°C) are aimed for. In summer they will take a little more heat. A nighttime temperature drop to below 65°F (15°C) is important for flowering.
   
7. Flowers
   In full bloom Oncidium Orchids form large bracts of flowers. You may need to use a flower stick and orchid clip to support this.
8. Repotting
   Use a free draining mix, 80% medium to fine bark with 20% coarse perlite. You will need to repot every 2 – 3 years.
   Always grow Oncidiums in smallish pots for the plant size. The best time to repot is in spring when they are in active growth.

Species and varieties

Species include Oncidium sphacelatum and Oncidium incurvum however with over 200 species and a huge number of cultivars or hybrids the variety is huge.

Many hybrids are available including varieties such as Bratonia estrelita, pictured.  others go under names such as Beallara, Burrageara,  and Colmanara.

Common Problems

• Over watering in winter.
• Lack of humidity.
• To little light in winter.
• To much light in summer.
• Over fertilisation.
• Poor drainage.
• Over potting.

Oncidium Orchids are available for sale online from the following growers.

MT BEENAK ORCHIDS
27 Hackett Rd Three Bridges VIC 3797
Large range of Masdevallia Seedlings & Species, Zygopetalum Alliance Hybrids, Odontoglossum Alliance Mericlones, Miscellaneous Genera Hybrids, Sphagnum Moss
www.mtbeenakorchids.com.au