Temperature requirements

Oncidiums are found in a wide range of habitats, from semi-arid subtropical lowlands to cool, misty cloud forests. Typically, 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. Avoid exposing the plant to cold drafts or temperatures below about 10°C, as this could slow the plant's growth if exposed for long periods.

Water requirements

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

Oncidiums love water, but the key 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 the orchid needs to be watered again. Watering frequency varies depending on the substrate used, the ambient temperature, and the ventilation provided. Oncidiums prefer clean water without too many minerals.

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

Humidity requirements

Oncidiums require specific humidity levels, at least between 40% and 50%. However, these plants love humidity, so the ideal range is actually between 55% and 75%. If this isn't possible, make sure the humidity never drops below 40%. The higher the temperature, the higher the humidity, and the higher the humidity, the more frequently and for longer you need to ventilate the room where your orchids are kept. Otherwise, there's a high risk of leaf rot and various fungal diseases.

Using a humidifier tray is one of the best ways to achieve any humidity level. These trays are simply a container of water filled with gravel. Gravel-filled trays are filled with water to just below the surface. To prevent plants from sitting on constantly wet gravel, plants are placed on small saucers or pieces of plastic or metal mesh placed over the trays. A full and swollen 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. The most popular species include O. leucochilum, O. longipes, O. sarcodes, O. pulchellum, as well as many hybrids. While 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 occur any time of year, but it is generally most intense in fall and spring. Many hybrids can flower 2-3 times a year. To initiate flowering spikes, it is important to grow the plant in an area where nighttime temperatures drop below 18°C ​​(64°F). Plants growing near a window are typically a couple of degrees cooler than the rest of the house. Oncidium flower spikes generally reach medium to tall length and branch out in various directions.

Fertilizer requirements

These orchids require sufficient nutrients to thrive. It's therefore important to fertilize them regularly, otherwise they won't be healthy. However, over-fertilization is harmful to the plant. If the weather is cloudy, monthly applications are sufficient. Be sure to clean off any salt deposits monthly to avoid burning the Oncidium orchid's roots. During the growth phase, avoid excessive use of fertilizers high in phosphorus.

Recommended fertilizers:

• Balanced fertilizer for growth: 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 fertilizer for flowering: 0-52-34 (MPK) – 1 gram per liter of water – Spray every two weeks (14 days) – except during flowering.

Repotting, substrates and propagation

Oncidiums like to be lightly underpotted in a well-draining bark-based potting mix. Many oncidiums will form large clusters of pseudobulbs and develop into rather large plants. They can be easily divided into groups when repotting. Just make sure there are at least three pseudobulbs in each division. In general, repot only when necessary. Aggressive repotting can kill an orchid. Oncidium orchids have thin roots, so repotting is very delicate work. 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 nutrients, both in the wild and in cultivation. For these reasons, the type of growing medium is very important. They can usually survive in leaf mold, but using this type of soil is not recommended. It's important to use the best soil for epiphytes, such as charcoal, coco peat, or pine bark. The coco peat fibers will provide adequate drainage for your orchid, which is essential for its growth.

Choosing the right pot is also important. Never choose a pot that's 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 damp and very moist, which can damage the roots and cause them to rot.

Plants repotted in bark mix should be removed carefully. Remove the roots from the old mix, taking care not to break the healthy roots. However, it is inevitable that roots will break during repotting. Diseased roots that should be removed are those that are brown, soft, or papery. White or beige roots that are firm to the touch should be left intact. Simply transfer the plant to a new pot, placing the older growth toward the bottom of the pot so that there is room for new growth to develop for about 1-2 years. Oncidiums can be divided when there are 6 or more pseudobulbs. Divide, leaving 3 growths for each division.

Parasites and other problems related to Oncidium

Fungal and bacterial diseases of Oncidiums are common due to the moisture levels and substrate they require to survive. Fungal diseases cause problems such as root rot, leaf spots, leaf discoloration, and flower spots.