Oncidium Alliance Culture

Pronounciation: on-SID-ee-um
Common Name: Dancing Lady Orchid
Distribution: South America


These are a large and diverse group of orchids They are found anywhere from the coast to the tropics to the upper parts of the mountains. This makes it very difficult to give a general cultural recipe.

They are considered as intermediate to warm growers, and will benefit from temperatures ranging from: 12 C at night to about 30 C during the day. They will tollerate temperature of upto 38 C if there is sufficient humidity and air movement.

Most Oncidiums will do well with one to several hours of sun a day. The thick leaved plants can stand more light than the thin leaved Oncidiums. They will thrive with about 2000 to 6000 footcandles of light.

Watering and Humidity
My Oncidiums are grown at around 50% to 80% humidity , with constant air movement. Humidity is always a problem, getting the right mix is difficult, you can raize the hummidity in a few ways, for example by placing flat trays filled with stones and then partially filled with water, and standing the pots on top of the stones. In a greenhouse, I put down a sheet of plastic on the ground, and then gravel ontop of that, and everyday I flood the floor, this increases the humidity to the correct amount. You can also use an evaporative cooler, and a misting system. Cultured Orchids obtain water in two ways, one is by the humidity in the air, the other is by watering directly in the pot. I water my orchids from the fish pond and they seem to love it. You will have to learn from your orchids when to water them, it is difficult to say that they should be watered every 3rd or 4 th day, because this depended on several factors, such as potting mix, humidity, type of pots and quality of water. I was once told, " if in doupt, wait another day..."

Repotting and Potting mixes
There is a wide range of mixes available at present. Cattelyas will grow in anything from tree bark to stones. There are various potting mediums, such as osmunda (expensive), tree fern, bark, moss, CHCs (coconut husk chips), perlite, vermiculite, Semi-Hydro (used in the hydroponics industry) sponge rock and rockwool (extruded melted rock). It must just be remembered that whatever medium you use, it should be a free draining one. Oncidiums need to be repotted about every two to three years, or as the medium decomposes. Our seedlings and smaller plants are repotted more often. When it comes time to devide a large plant, you must alway leave at least at least 3 to 5 pseudobulbs.

Must be done on a regular basis. When using bark as a potting medium you need a high nitrogen fertilizer (30-10-10), alternating occasionally with a high-phosphorus or bloom booster (10-30-20). If you grow your Oncidiums mounted on wood or slabs or even potted in an inhert medium, you should fertilise with a balanced 20-20-20 fertiliser. Actively growing plants need to be fertilised once a week, and about once every two weeks during dormancy. The pots need to be flushed occasionally to leach out any fertiliser salts from around the roots. I prefer to foliar feed my orchids about twice a week, and they are thriving. I use an organic fish and kelp emulsion.