Temperature Requirements

Oncidiums are found in many habitats, from semi-arid subtropical plains to cool, misty cloud forests. Generally, the most popular Oncidiums, characterized by small yellow flowers, large pseudobulbs, and ribbon-like leaves, are intermediate or warm temperature orchids.

Therefore, the ideal requirements are a daytime temperature of 26-30 °C and a nighttime temperature of 13-16 °C. Temperatures up to 35-38 °C are tolerated, as long as humidity and air movement are increased as temperatures rise, a good general rule in any case. Do not expose to cold drafts or temperatures below about 10 °C, as this could slow down the plant’s growth if exposed for too long.

Water Requirements

It’s important to know how to water your Oncidium orchid. Both overwatering and underwatering are common mistakes. Oncidiums generally have different water needs during different stages of their growth, but a general rule is that they should never be overwatered. Oncidiums store water in their pseudobulbs, making them more tolerant of dry than wet substrate. In general, Oncidium orchids require more water when they begin to grow and flower. This is the only stage where they require a relatively high amount of water. After this stage, it’s best to water less.

Oncidiums love water, but the secret is to provide adequate drainage. Otherwise, the roots will drown, lose oxygen, and rot. This will kill the orchid. For this reason, overwatering is not a good idea for these orchids. On the other hand, if you notice that the topsoil is completely dry, it’s usually a sign that you should water the orchid again. The frequency of watering varies depending on the substrate used, ambient temperature, and ventilation provided. Oncidiums prefer clean water without many minerals.

In winter, reduce watering to once every two months or less. They can withstand considerable drought thanks to their large pseudobulbs. Wrinkled pseudobulbs generally indicate a lack of water.

Humidity Requirements

Oncidiums need specific humidity levels, at least between 40% and 50%. However, these plants love humidity, so the ideal is actually between 55% and 75%. If you cannot provide this, make sure humidity levels never drop below 40%. The higher the temperature, the higher the air humidity must be, and the higher the air humidity, the more often and longer you need to ventilate the room where you keep the orchids, otherwise there is a high probability of rot and the appearance of various fungal diseases on the leaves.

Using a humidity tray is one of the best ways to achieve any humidity level. These trays are nothing more than a water container filled with gravel. Gravel-filled trays are filled with water to a level just below the surface. To prevent plants from resting on constantly wet gravel, plants are placed on small saucers or pieces of plastic or metal mesh placed over the trays. A full, plump pseudobulb indicates a well-hydrated plant.

Flowering

Oncidiums are magnificent in bloom. A large, well-grown plant can produce six or seven branches of yellow flowers. The effect is very similar to a cloud of butterflies. Popular species include O. Leucochilum, O. Longipes, O. Sarcodes, O. Pulchellum, as well as many hybrids. Although Oncidiums are known for their yellow flowers, other varieties are available. O. Sharry Baby is sometimes called the “chocolate orchid” for its brownish flowers in clusters with a rich cocoa scent.

Depending on the variety, the flowering season can be at any time of year, but it is generally most intense in autumn and spring. Many hybrids can flower 2-3 times a year. To initiate spiking, it is important to grow the plant in an area where nighttime temperatures drop below 18 °C. Usually, plants growing near a window are a couple of degrees cooler than the rest of the house. Oncidium flower spikes generally reach a medium or high length and branch in different directions.

Fertilizer Requirements

These orchids need enough nutrition to thrive. It is therefore important to fertilize them regularly, otherwise they will not be healthy. However, excessive fertilization is harmful to the plant. If the sky is cloudy, monthly applications are sufficient. Make sure to clean any salt deposits monthly to avoid burning the roots of the Oncidium orchid. During the growth phase, avoid excessive use of high-phosphorus fertilizers.

Recommended Fertilizers:

• Balanced Growth Fertilizer: 20-20-20 (NPK) – 1 gram per liter of water – Spray once every two weeks (14 days) – During flowering periods (once a month)
• High-Phosphorus Flowering Fertilizer: 0-52-34 (MPK) – 1 gram per liter of water – Spray every two weeks (14 days) – except during the flowering period.

Repotting, Substrates, and Propagation

Oncidiums like to be slightly underpotted in a very well-draining bark-based soil mix. Many Oncidiums will form large clumps of pseudobulbs and develop into rather large plants. They can be easily divided into clumps when repotting. Just make sure you have at least three pseudobulbs in each division. In general, only repot when necessary. Aggressive repotting can kill an orchid. Oncidium orchids have thin roots, so repotting is a very delicate job. They should be repotted about once every two years. Like many orchids, once an Oncidium has adapted to its conditions, it should not be difficult to grow.

The wrong growing medium can be very dangerous for your Oncidium orchid. These orchid species generally require a lot of nutrition, both in nature and in cultivation. For these reasons, the type of growing medium is very important. They can usually survive in a leaf mold, but using this soil is not recommended. It is important to use the best soil for epiphytes, such as charcoal and coconut peat or pine bark. The fibers of coconut peat will provide adequate drainage for your orchid, which is crucial for its growth.

Choosing the right pot is also important. Never choose a pot that is too large for your Oncidium. These orchids are best kept in small, narrow pots. The smaller the pot, the better. Large pots often make the soil moist and very wet, which can damage the roots and cause them to rot.

Plants repotted in a bark mix should be carefully removed. Remove the roots from the old mix, being careful not to break healthy ones. However, it is inevitable that roots will break during repotting. Roots that are diseased and need to be cut are those that are brown, mushy, or papery. Those that are white or beige and firm to the touch should be left intact. Simply transfer the plant to a new pot, placing the oldest growth towards the bottom of the pot so that there is room for new growths to develop for about 1-2 years. Oncidiums can be divided when there are 6 or more pseudobulbs. Divide, leaving 3 growths per division.

Pests and Other Oncidium-Related Problems

Fungal and bacterial diseases of Oncidiums are common due to the humidity levels and substrate they need to survive. Fungal agents cause problems such as root rot, leaf spots, leaf blights, and flower spots.