Oncidium varicosum, commonly known as the “Dancing Lady Orchid,” is a captivating plant. Its sprays of vibrant, often yellow, flowers resemble tiny dancers in full skirts. This guide explores the specific care requirements for cultivating a healthy and flourishing Oncidium varicosum plant.
Understanding Oncidium Varicosum
Oncidium varicosum is an epiphytic orchid, growing on other plants like tree trunks and branches, rather than in soil. It is native to the semi-tropical forests of Brazil, Bolivia, and Paraguay, typically at elevations between 500 to 1800 meters. This habitat, with humid summers and drier winters, influences its care. The plant features ovoid, elongated pseudobulbs, which are storage organs, typically 4-8 cm long. Each pseudobulb supports two to three flexible, lanceolate leaves, often 15-23 cm long. Its distinctive flower spikes are long, branched, and flexible, emerging from the base of new season bulbs, often showcasing a large, bright yellow lip.
Cultivating Oncidium Varicosum
Light Requirements
Oncidium varicosum thrives in bright, indirect light, similar to its natural habitat under a tree canopy. Provide about 1-5 hours of direct morning sun daily. Placement near an east, south, or west-facing window with sheer curtains offers suitable filtered light. Dark green leaves indicate insufficient light, while a reddish tint suggests too much.
Watering Practices
Watering Oncidium varicosum requires allowing the potting medium to dry slightly between waterings, considering its epiphytic nature. Overwatering can lead to root rot, so ensure good drainage.
During spring and summer, water more frequently, sometimes daily or every other day. In autumn, weekly watering may suffice. In winter, reduce watering, providing just enough water to prevent pseudobulbs from shriveling. Use lukewarm or room-temperature water.
Temperature and Humidity
These orchids prefer intermediate to warm temperatures, with ideal daytime ranges of 27-29°C (80-85°F) and nighttime temperatures of 13-16°C (55-60°F). A daily temperature difference of about 10-11°C is beneficial. Higher temperatures up to 35-38°C (95-100°F) are tolerated with increased humidity and air circulation. Maintain humidity levels between 75-80% for most of the year, dropping to 65-70% in drier periods. Pebble trays or humidifiers help achieve these levels, and good air movement prevents fungal issues.
Potting and Repotting
Oncidium varicosum prefers a free-draining, bark-based potting media, often a mix of bark, sphagnum moss, or charcoal. These orchids thrive when slightly underpotted, preferring their roots to be somewhat tightly packed. Repot every two years or when the medium breaks down, typically after flowering in spring or autumn. When repotting, handle delicate roots carefully and position the newest growth towards the pot’s center, allowing space for future growth.
Fertilization
Regular fertilization during active growth supports healthy development. Use a balanced orchid-specific fertilizer, such as a 20-20-20 formulation, for plants in bark-based media or on mounts. Fertilize fortnightly from spring through summer, diluted to one-quarter to one-half the recommended strength. During winter, or when the plant is not actively growing, reduce or stop fertilizer application.
Encouraging Blooms and Post-Bloom Care
Encouraging Oncidium varicosum to bloom involves providing optimal light and a slight temperature fluctuation. Bright, indirect light is essential; flower spikes often develop in summer, blooming in autumn or winter. A temperature drop of about 10°C (18°F) between day and night can help trigger blooming. A slight reduction in watering after new pseudobulbs mature, allowing the potting mix to dry out more between waterings, can also encourage flowering.
After blooms fade, cut the brown spike back at the base using a sterilized tool. This prevents the spread of pests or diseases. Return the plant to its regular watering and fertilization schedule to support new growth.
Propagating Oncidium Varicosum
The primary propagation method for Oncidium varicosum is pseudobulb division. Perform this during repotting, ideally when new root growth begins. To divide, carefully separate pseudobulbs, ensuring each new division has at least three to four healthy pseudobulbs and a good root system.
After division, pot each section into its own container using a fresh, well-draining orchid mix. Position the oldest growth towards the back of the pot to allow space for future new growths. Maintain high humidity and allow the potting medium to dry between waterings after repotting to help plants establish roots.
Common Issues and Solutions
Oncidium varicosum can encounter common problems. Overwatering or insufficient air circulation can lead to root rot, characterized by soft, discolored roots. Ensure the potting medium drains well and dries adequately between waterings.
Wrinkled pseudobulbs often indicate underwatering or low humidity, signaling a need for more consistent moisture or increased ambient humidity. Pests like spider mites, mealybugs, and scale insects can also affect your orchid. Regular inspection, especially of leaf undersides, helps in early detection.
For minor infestations, wipe pests with a cotton swab dipped in rubbing alcohol or a mild soap and water solution. Good air circulation and maintaining proper humidity levels help deter pests like spider mites, which thrive in dry conditions. Keeping the growing area clean by removing debris minimizes pest and disease risks.