Monstera
Monstera deliciosa
Toxic to pets
Oncidium Orchid
Oncidium altissimum · Orchidaceae
Moderate
Pet-safe
Oncidium altissimum is an epiphytic orchid native to the Caribbean, including Jamaica, Trinidad, and parts of Central America, where it grows on tree branches in warm, humid forests. It produces tall, branching panicles that can reach over a metre in height, bearing numerous small yellow and brown flowers with a characteristic ruffled lip. It is grown as a houseplant for its dramatic floral sprays and relatively tolerant nature compared with more demanding orchid genera.
☀ Light
Bright indirect light, some direct morning sun
💧 Water
Water thoroughly then allow to nearly dry between waterings
🌡 Temp
18-30°C, avoid below 15°C
💦 Humidity
50-70% relative humidity
🌿 Soil
Coarse, free-draining bark-based orchid mix
🍽 Feeding
Half-strength balanced orchid fertiliser every 2-3 weeks when in growth
Photo: Sarah Ann Drake / Public domain via Wikimedia Commons
How to care for Oncidium Orchid
Light
Oncidium altissimum thrives in bright, indirect light with some exposure to gentle morning sun. A position near an east- or west-facing window is ideal. Direct midday or afternoon sun should be avoided as it will scorch the pseudobulbs and leaves, causing yellowing or brown patches. If natural light is limited, a full-spectrum grow light placed 30-40 cm above the plant for 12-14 hours per day can compensate adequately.
Watering
Water thoroughly when the growing medium is almost, but not completely, dry. Pour water evenly over the medium and allow it to drain fully; never leave the pot sitting in standing water as this promotes root rot. During active growth in spring and summer, watering is typically required every 5-7 days depending on temperature and humidity. Reduce frequency in autumn and winter when growth slows, allowing the medium to dry a little more between waterings. Use rainwater or filtered water at room temperature where possible, as cold tap water and mineral-heavy water can damage roots over time.
Soil and potting
This species requires an extremely free-draining, airy growing medium that mimics its epiphytic natural habitat. A coarse bark-based orchid compost, ideally medium-grade fir bark supplemented with perlite and charcoal, is suitable. Standard houseplant potting compost must not be used as it retains too much moisture and will cause root suffocation and rot. The medium should be replaced every 1-2 years as the bark breaks down and drainage deteriorates.
Feeding
Feed with a balanced orchid fertiliser at half the manufacturer's recommended strength every 2-3 weeks during the growing season from spring through early autumn. A fertiliser with an NPK ratio of approximately 20-20-20 or one formulated specifically for orchids is appropriate. Reduce feeding to once a month or stop entirely in winter when the plant is not in active growth. Flush the medium with plain water once a month to prevent salt and mineral build-up, which can damage roots.
Humidity and temperature
Oncidium altissimum prefers daytime temperatures of 21-30°C and tolerates a night-time drop to around 15-18°C, which can encourage flowering. It should not be exposed to temperatures below 13°C, and cold draughts from windows or air-conditioning units should be avoided. Humidity of 50-70% is preferred; in dry indoor environments, placing the pot on a tray of damp pebbles, grouping plants together, or using a room humidifier will help maintain adequate moisture in the air. Misting directly onto leaves is not generally recommended as it can encourage fungal issues if ventilation is poor.
Repotting
Repot every 1-2 years, ideally in spring just as new root growth begins. Choose a pot that is only slightly larger than the current one, as Oncidium species tend to flower better when slightly root-bound. A clear plastic pot or a slotted orchid pot is useful for monitoring root health. Gently remove the old bark, trim any dead or rotting roots with sterile scissors, and dust cut ends with powdered cinnamon or a fungicide before repotting into fresh orchid bark mix.
Pruning
After flowering, the spent flower spike can be cut back to the base of the spike using clean, sharp scissors or secateurs. Unlike some Phalaenopsis orchids, Oncidium altissimum does not reliably rebloom from old spikes, so removing them tidily encourages the plant's energy to go into producing new pseudobulbs. Remove any dead, yellowing, or damaged leaves as they appear by cutting cleanly at the base. Always use sterilised tools to avoid transmitting infection between cuts.
Is Oncidium Orchid toxic?
Pets: Non-toxic. Oncidium orchids are not listed as toxic to cats or dogs by the ASPCA. Ingestion of plant material is unlikely to cause serious harm, though mild gastrointestinal upset from consuming non-food plant matter is always possible in sensitive animals.
People: Not known to be toxic to humans; the plant is generally considered safe to handle and display in households with children, though ingestion of plant material is not recommended.
People: Not known to be toxic to humans; the plant is generally considered safe to handle and display in households with children, though ingestion of plant material is not recommended.
Common problems
Yellowing or shrivelling pseudobulbs
Likely cause: Underwatering or excessively dry conditions causing dehydration of stored water reserves Fix: Increase watering frequency and check that the medium is not completely dry for extended periods; raise ambient humidity if possible
Soft, brown, mushy roots and wilting despite moist medium
Likely cause: Root rot caused by overwatering or a medium that retains too much moisture Fix: Remove the plant from its pot, trim all rotten roots back to healthy tissue with sterile scissors, allow to air dry briefly, and repot in fresh, coarse orchid bark with improved drainage
Brown, bleached or papery patches on leaves
Likely cause: Sunscorch from exposure to direct midday or afternoon sun Fix: Move the plant to a position with bright indirect light or filter direct sun through a net curtain; damaged tissue will not recover but new growth should be healthy
Sticky residue on leaves, stems or nearby surfaces, sometimes with sooty mould
Likely cause: Infestation of scale insects or mealybugs excreting honeydew Fix: Remove visible pests manually with a cotton bud dipped in isopropyl alcohol, then treat with neem oil solution or an appropriate systemic insecticide; repeat every 7-10 days for several weeks
Fine webbing on undersides of leaves with speckling on the leaf surface
Likely cause: Red spider mite infestation, typically encouraged by hot, dry indoor conditions Fix: Increase humidity, wash leaves with a damp cloth, and treat with a miticide or neem oil; isolate the affected plant to prevent spread
Failure to flower despite otherwise healthy growth
Likely cause: Insufficient light, lack of a suitable temperature differential between day and night, or the plant not yet mature enough to flower Fix: Move to a brighter location, ensure a night-time temperature drop of at least 5°C below the daytime temperature during autumn to stimulate flower spike initiation, and ensure the plant has at least 3-4 mature pseudobulbs
How to propagate
Division
When repotting, carefully separate the rhizome into sections, each containing at least 3-4 healthy pseudobulbs, using a sterile blade. Pot each division into fresh orchid bark and keep in a warm, humid position with reduced watering until new roots are established.
Back-bulb propagation
Older, leafless pseudobulbs (back-bulbs) can be detached at repotting time and potted individually in damp sphagnum moss. Kept warm and humid, they may produce new shoots from dormant buds, though this process is slow and not always reliable.
Where Oncidium Orchid comes from
Native to Caribbean islands, Trinidad, Venezuela, Colombia, Central America.
Story and origins
The genus name Oncidium is derived from the Greek word 'onkos', meaning a tumour or swelling, referring to the warty or callus-like protuberance found on the lip of many species in the genus. The species epithet 'altissimum' is Latin for 'tallest' or 'very tall', a direct reference to the exceptionally long, branching flower spikes that distinguish this species within the genus. The name was formalised by the Swedish botanist Olof Swartz in 1800.
Oncidium altissimum was formally described by Olof Swartz in 1800 based on specimens collected from the Caribbean, where the species grows widely across Jamaica, Trinidad, the Lesser Antilles, and parts of Central America. European interest in tropical orchids grew enormously during the nineteenth century, driven by the fashion for orchid collecting known as orchidelirium, and Caribbean species including Oncidium altissimum were among those brought into cultivation for the grand glasshouses of wealthy collectors and botanical gardens. Today the species is less commonly grown as a specimen plant than many of the numerous Oncidium hybrids it has contributed to, but it remains valued by orchid enthusiasts for its dramatic, tall flower spikes and its representation of the wild forms from which so many cultivated varieties have been developed.
Varieties to know
Oncidium altissimum var. jamaicense
A Jamaican variant sometimes noted for slightly larger individual flowers and locally distinct colour patterning on the lip.
Oncidium 'Sharry Baby'
A popular hybrid involving Oncidium species, known for its chocolate-scented flowers; not altissimum itself but often sold alongside it and frequently confused with species forms.
Oncidium sphacelatum
A closely related species sometimes confused with altissimum, bearing similar yellow and brown flowers on tall panicles; widely available in cultivation.
Fun facts
- The flower spikes of Oncidium altissimum can exceed 1.5 metres in length in optimal conditions, making it one of the taller-flowering Oncidium species in cultivation.
- The common name 'dancing lady orchid' refers to the resemblance of the ruffled lip and spreading petals to a figure in a full skirt, a characteristic shared across the broader Oncidium alliance.
- Oncidium altissimum produces pseudobulbs that act as water and nutrient storage organs, allowing the plant to survive short dry periods that would quickly kill most non-epiphytic houseplants.
- In its natural Caribbean habitat, Oncidium altissimum is pollinated by male oil-collecting bees of the tribe Centridini, which mistake the flowers for the oil-producing flowers of other plant genera.
- The genus Oncidium currently contains over 300 recognised species, and molecular studies have led to significant reclassification in recent decades, with many former Oncidium species moved to related genera such as Trichocentrum and Tolumnia.
Oncidium Orchid FAQ
Why are the leaves on my Oncidium altissimum turning yellow?
Yellowing leaves can result from several causes including overwatering, underwatering, too much direct sun, or natural ageing of older leaves at the base of the plant. Check root health first by inspecting the medium and roots; if roots are brown and mushy, reduce watering and improve drainage. If the medium is bone dry and roots appear shrivelled, increase watering frequency. The loss of the occasional older lower leaf is normal and not cause for concern.
How do I get my Oncidium altissimum to flower?
The plant needs to be mature (with at least 3-4 healthy pseudobulbs), receive sufficient bright indirect light, and experience a drop in night-time temperature of around 5-8°C compared with daytime during autumn. This temperature differential signals the plant to initiate a flower spike. Ensure feeding is reduced in late summer and withhold water slightly for a few weeks in early autumn to mimic the dry season conditions that trigger blooming in the wild.
How often should I repot my Oncidium altissimum?
Repotting every 1-2 years is generally recommended, timed for spring when new root growth is beginning. The main reason to repot is the gradual breakdown of the bark medium rather than the plant outgrowing its pot. A pot that is slightly snug tends to promote better flowering than an oversized container.
Can I grow Oncidium altissimum mounted on bark rather than in a pot?
Yes, mounting on cork bark or tree fern fibre is a very suitable method that replicates the epiphytic natural growing conditions of this species. Mounted plants require more frequent watering as the roots dry out quickly, and humidity should be maintained above 60%. This method is particularly successful in a greenhouse or humid growing cabinet.
Is Oncidium altissimum safe to keep if I have cats?
Oncidium orchids are not listed as toxic to cats or dogs by the ASPCA and are generally considered safe for households with pets. That said, ingestion of any non-food plant matter can occasionally cause mild digestive upset in cats, so it is sensible to place the plant out of reach as a general precaution.
What is the difference between Oncidium altissimum and the common hybrid Oncidiums sold in supermarkets?
The plants commonly sold as Oncidium orchids in supermarkets and garden centres are almost always complex hybrids bred for compact size, ease of care, and reliable flowering. Oncidium altissimum is the true species, which grows considerably taller flower spikes and is better suited to intermediate to warm growing conditions. The species tends to have slightly more specific requirements and a less predictable flowering season than the heavily selected hybrids.
Should I mist my Oncidium altissimum to increase humidity?
Misting is not recommended for Oncidium altissimum as water sitting on leaves and in the crown can encourage fungal and bacterial rots, particularly in conditions with poor air circulation. A more effective approach is to use a pebble tray filled with water beneath the pot, group it with other plants to create a microclimate, or use a room humidifier to raise ambient humidity to the preferred 50-70% range.
