Houseplant · Orchidaceae
Oncidium Orchid
Oncidium
Give it bright indirect light and a bark mix that drains fast, and the dancing lady orchid rewards you with sprays of fall flowers.
Bright indirect
Every 2–10 days
55–84°F · 13–29°C
USDA 9–12
Overview
The oncidium is the orchid people call the dancing lady, and the name lives in each flower's broad, ruffled lip, which flares open like a skirt caught mid-step. It grows wild in the warm forests of the Americas as an epiphyte, its pale roots clamped to rough tree bark rather than sunk in soil. That grip on bark shapes the whole plant.
In place of soil it sits in coarse, chunky bark mix that water rushes straight through. At the base of its leaves swell the pseudobulbs, firm green storage stems that hold moisture and let the plant coast through dry weeks, so the thin roots never sit wet. In fall most of the genus lifts tall, branching flower sprays that carry dozens of small blooms at once and hold them for three weeks or more.
Its moderate rating comes down to needing a precise setup rather than any weakness in the plant. Match the light, the bark, and the watering rhythm and this orchid holds on for years, unfurling a fresh crop of ruffled flowers each season.
Care
The short version: give it bright indirect light, plant it in a coarse fast-draining orchid bark mix, and water only once the bark has dried about halfway, easing off in winter.
Light
Oncidiums want bright, indirect light for most of the day, the kind that lands soft rather than searing. An east-facing window with gentle morning sun fits, while harsh midday sun scorches the blades and deep shade leaves them dark and flowerless.
Water
Pour room-temperature water through until it runs from the pot, doing this once the coarse bark has dried about halfway, which can be every few days in summer heat or as little as every 10 days in cool spells. Cut back in winter. Above all, the fine, thread-like roots must never sit soggy, since that is the quick path to rot.
Soil
Skip smooth potting soil and use a coarse well-drained epiphytic orchid bark mix. Its rough chunks echo the tree bark this orchid clings to in the wild, hold a slightly acidic pH around 5.0 to 6.0, and leave wide gaps that let air reach the roots.
Temperature
Ordinary household warmth suits it, anywhere from 55°F to 84°F (13°C to 29°C). It takes a fairly wide span, so the main thing is to keep it clear of cold drafts and the dry gusts off heating vents.
Humidity
This orchid likes damp air around 50% to 70% humidity. In a dry room, set the pot over a tray of wet pebbles or run a humidifier close by, and keep the air stirring so beads of water do not linger on the leaves.
Feeding
Across the spring-to-summer growing season, feed weekly with a balanced orchid fertilizer thinned to quarter or half strength. Pour it on right after watering so the diluted feed never hits dry roots.
Pruning
Once the small flowers shrivel and drop, cut the spent flower spike back to its base. Past that, the plant asks only for the removal of dead or rotted roots and yellowed leaves.
Repotting
Repot about every 2 years in spring, when the new growth is roughly half mature. The cues are pale roots arching over the rim, plump pseudobulbs pressing at the edge, and bark crumbled to fine grit that no longer drains.
Size & spacing
Size ranges widely across the genus, from squat miniatures near 6 inches (15 cm) tall to towering plants reaching 10 feet (3 m) in bloom, and spreading anywhere from 3 to 48 inches (8 to 122 cm) wide. Pick a variety scaled to the spot you have in mind.
Troubleshooting
Most oncidium trouble hides down among the roots or writes itself across the leaves as a shift in color. Catch those first marks and the plant usually pulls through. Match what you see below, then act before it spreads.
Soft, brown-to-blackened roots beneath a wilting plant
Those roots gone soft and brown, sometimes near black and collapsing between your fingers, are the mark of root rot. Soggy mix causes it far more than dryness, because bark that has broken down packs tight and smothers the fine roots. Slip the plant free, cut away each brown, hollow root with sterile tools, nest it in fresh bark, and hold off water until it settles.
Fix:
- Remove the plant from the pot and trim away all rotted roots with sterile tools
- Repot into fresh, well-drained orchid bark
- Resume watering only when the mix approaches half-dryness
White cottony tufts or small brown bumps in a sticky glaze
Tufts of white cotton or hard, limpet-shaped brown bumps sitting in a sticky glaze mean mealybugs or scale have wedged into the leaf axils and along the pseudobulbs. Roll each one off with a cotton swab soaked in isopropyl alcohol, then coat the plant with horticultural soap or oil. Keep it clear of the rest of the collection until not one insect is left.
Fix:
- Wipe insects off with a cotton swab dipped in isopropyl alcohol
- Treat with horticultural soap or oil
- Isolate the plant until the infestation clears
Leaves flushed reddish, bleached pale, or gone unusually dark
The color washing across the leaves is a signal about light. A reddish flush or a pale, bleached cast shows the sun is too strong and searing the surface, while soft, deep green blades that hang limp point to too little light. Set it in bright, indirect light, out of the hard midday sun, and the blades firm up and deepen to an even mid-green.
Fix:
- Move the plant to bright, indirect light
- Shield from harsh midday direct sun
Toxicity
Good news for homes with pets and children: the oncidium is non-toxic from its pale roots to its ruffled flowers. The ASPCA lists the dancing doll orchid as safe for cats, dogs, and horses, and the wider orchid family carries no known poisons. A pet that chews a leaf might drool or feel briefly queasy, but nothing here will do it real harm.
Safe for
People · Cats · Dogs · Horses · Rabbits · Livestock · Birds
Cats None
A cat that bites into the smooth green blades meets no toxins at all. The worst that follows a chewed leaf is a little drool or a single bout of vomiting, and it clears on its own.
Dogs None
Dogs can chew the foliage without harm. A pup that shreds a leaf into ragged strips may get a brief upset stomach, but no poisoning follows.
Horses None
The plant poses no danger to horses. A cropped mouthful of leaf leads to nothing worse than mild, short-lived stomach upset.
Rabbits None
Rabbits face no toxic risk from any part of this orchid. As with any fresh green, a large helping at once might loosen the stomach for a day.
Livestock None
Goats, sheep, and cattle can browse the leaves safely. The tissue holds nothing that would make them sick.
Birds None
Pet birds can perch on the stems or peck at the leaves without harm, since no part of it is poisonous to them.
People None
The orchid is harmless to people, including children who handle the ruffled flowers. It is not grown to be eaten, so there is no reason to taste it.
No toxic compounds, but ingested fertilizer or pesticide residue on leaves could cause mild stomach upset, and eating plant material may cause transient vomiting.
Varieties
Thousands of oncidium species and hybrids exist, but a few keep turning up in shops and on windowsills. These are the ones worth knowing by name.
Oncidium 'Sharry Baby'
A popular hybrid whose blooms release a heavy chocolate-and-vanilla scent that fills a room.
Oncidium 'Twinkle'
A compact miniature studded with many tiny fragrant flowers on a plant small enough to sit on a windowsill.
Oncidium sphacelatum
The popcorn orchid, whose long branching sprays crowd close with small bright yellow-and-brown flowers.
How to propagate
Left alone, an oncidium packs its pseudobulbs into a tight clump, and the simplest way to make more is to pull that clump apart when you repot.
DivisionModerate
At repotting in spring, when new growth is about half mature · About 1-2 years to re-establish and bloom
An oncidium splits at repotting in spring, once the new growth is about half mature, the clump of plump pseudobulbs pulling apart at their joints. Leave at least three pseudobulbs and a fan of healthy roots on each piece, since a smaller division sulks and may not flower. Each new plant then needs 1 to 2 years to settle in and bloom again.
Myths
Orchids are parasites that feed off the trees they grow on.
An oncidium is an epiphyte, not a parasite. Its roots grip the bark of a tree only for a hold and pull water and nutrients from rain, damp air, and the loose debris that lodges around them. It takes nothing from the host tree itself.
Watering any orchid with ice cubes is the right way to do it.
Oncidiums grow in intermediate-to-warm conditions, and a slow bead of cold meltwater never soaks the coarse bark the way they need. Water them thoroughly with room-temperature water once the mix has dried partway, and leave the ice out.