Oncidium orchids are a large and wide-ranging genus of orchids. The genus boasts over 300 species, some estimates are as high as 700, but the commonly accepted number is closer to 330.
Oncidiums are nicknamed Dancing Lady Orchids because the shape of their flowers is reminiscent of a dancer in a long skirt. The flowers are small and dance on their stems with any passing breeze.
These lovely plants are native to Central and South America and even some parts of southern Florida. Because of the wide range of landscapes where they are found, they also adapt to different light and climate conditions.
Oncidium ownership can be complex and nuanced, so the more delicate of the genus are not typically recommended for first-time orchid growers. However, some sturdier varieties make quite a good first orchid with their relative ease of care. They tend to be more delicate than some of the larger blooming orchids, from their flowers down to their roots.
However, these orchids do quite well in the home environment regarding temperature and humidity needs, so it may be a chance you are willing to take. Let’s look at this interesting group of orchids and find out what makes them tick.
Oncidium Orchid Overview
Oncidiums are perennial epiphytes that grow on trees, forming roots around trunks with a sympodial growth habit.
Oncidium orchids are classified as perennial, sympodial epiphytes. Perennial, of course, refers to their habit of growing and blooming year after year without the need to replant. All orchids are perennial, and most bloom just once per year.
Epiphyte refers to the habit of growing in and around trees. In their native habitat, oncidium orchids grow in the lush jungle landscapes of Central and South America. They form roots around the trunks of trees, where they hang on and absorb water and nutrients from the air around them. They are, essentially, air plants.
The word sympodial denotes the growth habit of this type of orchid. All orchids have a central rhizome or main stem. The orchid produces new growth, flowers, and roots from this rhizome. A sympodial orchid has a rhizome that grows horizontally, sending up successive pseudobulbs, with each one producing its own leaves, flowers, and roots.
These orchids have a unique flower formation featuring 3 uniform sepals and a showy labellum resembling a dancer’s skirt.
Oncidium orchids have a similar flower formation to the phalaenopsis orchid. There are three uniform sepals, the outer petals that form the bud enclosure.
The sepals are typically the same relative size, shape, and color as the two upper petals. So, in terms of physical appearance, oncidium orchids appear to have 5 uniform petals, usually narrow and pointed at the ends.
The labellum is what the oncidium orchid is best known for. A great majority of oncidium orchids have, proportionately, a very large, showy, and decorative labellum. The labellum is also known as the lip.
This lip acts as a landing pad for pollinators looking for a snack. The labellum connects to the column of the flower, which holds the flower’s reproductive system and is covered by an anther cap. This flashy lip is also the flower part that resembles a dancing lady’s skirt.
Propagating orchids can be a very simple and painless process, depending on your chosen method. Propagating from seed is the method least used by home gardeners because of orchids’ very long maturation period and the complicated process required for germination.
The most common way to propagate an orchid is by division, which is simple and generally very successful. The orchid’s epiphytic nature lends itself well to this method, and sympodial orchids are especially easy to divide.
These species have upward-growing pseudobulbs attached to a horizontal rhizome.
The Oncidium orchid comprises a series of sympodial pseudobulbs, each growing upward, attached to a central rhizome that runs horizontally. A monopodial orchid, which is the alternative, is an orchid that grows vertically along its rhizome and continuously produces new leaves and flower spikes from the same root system.
Because these orchids are sympodial, they are exceptionally easy to propagate by division. Each pseudobulb will grow its own set of leaves and produce its own flower spike. Once that flower spike drops its blooms, the pseudobulb is considered to be spent, as it will not produce flowers again.
Spent pseudobulbs have a responsibility to the whole plant. They store water and nutrients that assist the plant in producing and supporting new growth. For this reason, they should not be removed from the plant until they are brown and no longer living and supportive parts of the orchid.
Oncidium orchids can produce quite a lot of growth in a single year, so it is not uncommon to see an oncidium with multiple flower spikes. Never divide an orchid while it is in bloom, as this will dramatically shorten the life of the flowers.
To divide an Oncidium orchid, use a sharp, sterile blade and slice through the rhizome, leaving pseudobulbs intact on both divisions. It’s a good rule of thumb to wait until there are eight pseudobulbs before dividing a sympodial orchid. Each part can then be repotted and will continue to produce new growth.
Orchid seeds are very, very tiny. If you’ve ever scraped the inside of a vanilla bean and examined the gritty paste inside, you were looking at millions of orchid seeds! These seeds are so tiny that they store no endosperm and have no energy for germination.
These tiny seeds are also very vulnerable to bacteria and fungi, so if you plan on growing orchids from seed, get your seeds from a reputable source. There are two ways to germinate orchid seeds: symbiotically and asymbiotically.
Orchids in nature rely on mycorrhizal fungi for nutrients, which is challenging to replicate outside of a lab.
In their natural habitat, orchids circumvent their lack of nutrients and ability to process them by attaching to mycorrhizal fungi. The seed can then utilize the nutrients broken down by the fungi for its own growth.
This process is very difficult to duplicate in practice. In fact, outside of a sterile, controlled laboratory setting, it’s basically impossible. For that reason, I will stop here and move on to discuss asymbiotic germination.
Also known as flasking, asymbiotic germination involves germinating orchid seeds in a sterile glass container.
The method of performing asymbiotic germination is called flasking, as the seeds are germinated inside of a glass jar or flask to maintain a sterile environment during the lengthy process. Think of this as the in vitro fertilization of orchids.
Flasking provides an alternative to attempting symbiotic germination. The orchid seeds are placed into the flask with a nutrient-rich substance that they can utilize to germinate.
After germination, the orchid seeds must stay in the flask for a long time, up to 2 years, before the young plants can survive independently. After this, it will take several more years before the orchids are mature enough to produce flowers.
Growing Oncidium Orchids
Growing orchids is simple as long as you live in zones 10-12. In warm climates, all an orchid needs is to be tied to a tree and left on its own. The orchid will grow roots around the tree and should thrive if it doesn’t fall victim to pests or diseases.
For those of us living in colder climates, it’s not as easy. North of zone 10, orchids will need to be houseplants for at least a few months out of the year, and in the coolest areas for most of the year.
The most important factor in caring for orchids is to be observant. Pay attention to the leaves and general health of the plant. Your orchid will tell you what it needs.
Container type is crucial for orchids, with humidity being more important than planting depth.
The type of container used is more important than the depth at which an orchid is planted. Theoretically, if an orchid has the right humidity level, it can grow attached to a piece of tree bark and be quite happy. However, potting an orchid is useful as it makes watering and moving it about much easier.
Three types of common orchid pots are widely available. The main requirement for an orchid pot is airflow. Orchids need a lot of air circulation around their roots to prevent root rot. So, any orchid container must have adequate ventilation. The three types of common orchid pots are:
These rustic wooden, hanging baskets are a great way to pot outdoor orchids. They do a great job of imitating the natural environment of the orchid; water can flow through freely and so can air. The downside is that potting mix can also fall out and this gets messy in the house.
These are ideal for successful use and plant health. Terracotta absorbs water, wicking it away from the roots of the plant. Special orchid pots will look very much like any clay flower pot, but will have more drainage holes in the sides and base than other terracotta pots.
Similar to terracotta, these contain the potting mix well, and they look really pretty. However, there is a higher chance of overwatering as they don’t wick water away as terracotta does. In addition, many of them sit on an attached dish to catch excess water, and you’ll need to monitor and drain this dish as orchid roots should never sit in water for long periods of time.
Most orchids prefer filtered sunlight, while Oncidiums thrive on the sunnier side.
The majority of orchids prefer bright, filtered sunlight for most of the day. In their native environment, orchids receive most of their light filtered through the leaves of the tree they attach to. Oncidium orchids prefer to be on the sunnier side of the spectrum.
Oncidiums like a fair amount of sunlight, with some even tolerating full sun. Varieties with thicker leaves will prefer some extra sun, while those with more delicate leaves need about 20-60% shade.
An orchid will let you know when it is getting enough light. If an orchid produces a lot of dark green growth but no flowers, it needs more light. If you notice your leaves looking reddish, this is sunburn. Try giving the plant more shade. However, it is difficult to give oncidiums too much sun, in general.
Water when the potting medium is nearly dry, typically once a week indoors.
When watering, give these plants a good drench. Whether watering by immersing the pot or from the top, ensure the soil has ample time to absorb the water.
As a rule, the potting medium should be nearly dry before watering again. Indoors, once per week is good for most orchids. It’s good to water just slightly more often for species with very thin roots. You may need to water outdoor specimens every 3 to 5 days as they’re prone to drying out quicker than indoor plants are.
The integrity of an orchid’s roots determines its overall health. If kept too wet or too dry, they become more fragile and susceptible to fungus and bacteria.
Proper potting medium is crucial for orchids to ensure root aeration and prevent moisture issues.
Using the right potting medium is a major factor in keeping air circulating around your orchid’s roots. Regular potting soil holds too much moisture and doesn’t allow proper airflow. Orchids need a special potting mix if you want them to last longer than that first bloom.
Many orchids will come into bloom when potted in sphagnum moss. This is good for the plant while it is flowering, as the flowers will draw water. But when the flowers fall and the plant goes dormant, the moss will hold more moisture than the roots can absorb, and you will end up with weak roots.
Once an orchid is done blooming, it’s a good idea to repot it in a more fitting medium. Commercial orchid potting mixes are widely available. If you prefer to mix your own, blend 2 parts bark, 1 part charcoal, and 1 part sponge rock or pumice. This mix allows air to circulate around the roots and maintain the right moisture balance.
Climate and Temperature
Oncidiums thrive in temperatures of 70°-85°F, requiring additional water in high heat.
These plants prefer temperatures in the range of 70°-85°F during the day and 60°-65°F at night. Give your outdoor orchids a little more water in high heat. If you’re in a colder climate, when the temperature drops into the 40°-50°F range, it’s time to bring orchids in for the winter.
More important than temperature, orchids need a lot of humidity. Orchid roots are exposed in their natural habitat and will grow additional aerial roots above the potting medium in captivity. These additional roots and leaves take in water and nutrients from the air around them.
Oncidium orchids need at least 40% humidity but are quite happy getting up to 70%. This is high for most homes, so you may need to increase the humidity in the space around your orchids. A sunny bathroom or kitchen window are great places to house an orchid.
A plant humidifier is a good way to increase the humidity, but long periods of high humidity can damage other items in the home. Another solution is to place a dish of water with stones (called a pebble tray) under the orchid pot. The stones keep the orchid’s roots from sitting in water and rotting.
These plants benefit from regular fertilization using specialty or diluted balanced all-purpose fertilizers.
Orchids like to be fertilized regularly. Specialty orchid fertilizers are great, but using a balanced all-purpose fertilizer like 10-10-10 diluted to ½ strength is also perfectly fine. Fertilize once per week during the growing season and every 2-3 weeks during the off-season.
You should fertilize every time you water during the growing and blooming season. Once every 3 or 4 weeks, it’s a good idea to flush the roots with fresh water to remove any salt buildup on the roots.
Regular pruning is not recommended as it can slow new growth.
Oncidium orchids do not require regular pruning. Pruning an orchid will not encourage new growth in most cases. It can be tempting to remove spent pseudobulbs, but it is important to leave these intact until they have exhausted their resources. The spent pseudobulbs hold nutrients the plant will use to create new growth, so they should be left on the plant until they are brown and dry.
Sympodial orchids can be pruned in one fashion that will encourage new growth. Using a clean, sharp tool, slice halfway through the rhizome in between pseudobulbs to encourage the plant to produce additional pseudobulbs in these places.
There are a number of popular varieties within this orchid species. Let’s take a look at some of the most common, with names, pictures, and plant specifications of each.
‘Mother Teresa’ produces small yellow flowers with freckles and features a large yellow scalloped labellum.
Oncidium concolor ‘Mother Teresa’
Full to filtered sun or partial shade
This sweet sunshine of a plant comes from the jungle landscapes of Brazil and Argentina. It has small sepals and petals in yellow with a light smattering of freckles toward the center.
The labellum of this orchid is especially noteworthy. It is twice the size of the entire rest of the flower. The lip is bright yellow and scalloped on the outer edge, tapering down toward the column.
‘Sharry Baby Sweet Fragrance’
‘Sweet Fragrance’ is known for its chocolate-like scent and its beautiful deep oxblood blooms.
Oncidium Sharry Baby ‘Sweet Fragrance’
Full to filtered sun or partial shade
This variety is known far and wide for its sweet, chocolatey scent. In addition to this delectable characteristic, when mature, this orchid can produce multiple flower spikes of up to 3 feet long, each carrying up to 75 individual flowers!
The blooms are deep oxblood. 5 petals and sepals lean back slightly, and the bright white labellum protrudes forward. These little flowers sway and dance on their long delicate stems.
Oncidium twinkle ‘Pink Profusion’ boasts fragrant pink flowers.
Oncidium Twinkle ‘Pink Profusion’
Full to filtered sun or partial shade
This fragrant oncidium is a dwarf variety that fits perfectly in a sunny window. ‘Pink Profusion’ is easy to grow and has some of the prettiest flowers.
A profusion of flowers blooms on branched flower spikes. The blooms are medium orchid pink, and the labellum is a slightly deeper shade. The column and anther cap have accents of yellow and white.
Oncidium ‘Handsome’ produces tall spikes with profusely blooming bright yellow flowers covered with rust-colored spots.
Oncidium Pacific Passage ‘Handsome’
Full to filtered sun or partial shade
This is a gorgeous hybrid with tall, upright spikes that produce many cheerful blooms. This orchid likes moderate light, is easy to care for, and will reward the grower with many bright yellow blooms. The petals are all splotched with a rust color and have ruffled edges.
Oncidium catatante ‘Orange Kiss’ produces delightful exotic ruffled flowers in dark orange and reddish hues.
Oncidium catatante ‘Orange Kiss’
Full to filtered sun or partial shade
‘Orange Kiss’ is a hybrid of O. Sphecetanta x O. Wildcat. Its bright green foliage produces flower spikes in fall and spring. The blooms are exotic and delicate, as many oncidiums are. The 5 uniform petals and sepals are a deep orange shade, and the large, ruffled lip is orange where it connects and bright yellow at the end.
Pests and Diseases
Orchids are susceptible to several insects, as well as both bacterial and fungal infections. The best solution to these problems is diligence and hygienic gardening practices. Inspecting new plants before introducing them into your garden or home and using clean tools and water in plant care are important practices.
These small insects feed on the sap of young shoots resulting in stunted growth.
These little white bugs can do a lot of damage to an orchid in a short time. Mealybugs feed on the sap of new growth and flower buds, depleting the nutrients needed to thrive and bloom.
In addition to damaging new growth, mealybugs leave behind a sticky secretion that causes mold to grow, leading to rot.
Sadly, while minor outbreaks can be treated by touching the mealybug with a cotton swab dipped in rubbing alcohol (which forces it to release from the plant), large outbreaks of these guys require treatment with pesticides, and the treatment must be repeated after 10-14 days because of the short life cycle of these pests.
Always isolate an infected plant. Most infestations happen due to bringing in a new plant that already has a pest issue. Check out all new plants, particularly if you’re unsure of the retailer’s reputation.
Almost invisible, these tiny insects feed on the leaves of orchids, thereby discoloring them.
Spider mites are very tiny insects that multiply rapidly and feed on orchid leaves. The first sign will be a silvery discoloration on the tops of the leaves. They are so tiny that they are difficult to identify by sight alone.
One method of checking for spider mites is to hold a sheet of paper beneath a leaf and give it a couple of taps. If there are mites and eggs, you will see them fall to the paper. They will look like little specks, so don’t expect to recognize them as insects unless you use a magnifying glass.
Insecticides don’t work very well on mites, but outdoor predators do. Leaving an infested orchid outside for a few days can help. Mites tend to be worst in dry weather, so raising the humidity will also help keep them away.
Treat the plant with insecticidal soap or neem oil to get rid of thrips.
Thrips pierce buds and flowers with their mouthparts and suck out the nutrients, destroying those long-awaited flowers. Signs of these insects are premature browning and wilting of flowers and damage to leaves in the form of chlorotic spots.
Thrips can be detected with this easy test. Blow into the center of the flower and see if they crawl around in there. Isolate affected plants immediately to avoid spread and treat with insecticide soap or neem oil. You are likely to have to treat it more than once.
These small bugs feed on the sweet juice of young shoots, causing serious damage to plants.
Scales are the bane of the gardener’s existence. These sneaky little bugs come in on infected plants and reproduce rapidly, so it’s not hard for them to quickly become a big problem.
Scales feed on the sweet sap of tender new growth and flower buds. Scales can be treated with neem oil or other insecticidal oils, but it is best to catch them as early as possible, and if you purchase a plant and spot them, isolate it until they are gone.
For a small number of scales, use a cotton swab dipped in rubbing alcohol to kill them and wipe them away. But be careful, as this can damage the plant if overused.
These specialist pests prefer to chew the leaves of orchids and other plants.
These guys will ruin an orchid in no time flat. Fortunately, they rarely come indoors. They look like a beetle with a snout, and they like to munch on orchid leaves. They can chew up the leaves pretty quickly.
Their larva lives in potting soil, so if one enters your house, try to locate the adult, kill it, and then repot anything nearby to dispose of potential larvae. Insecticides are rarely needed, as you will see the damage of one adult very quickly before they can become a numbers issue.
To prevent Botrytis fungal infection, regulate humidity and air circulation.
Botrytis is the cause of petal blight. It most frequently appears on cattleya and phalaenopsis orchids, but other species are also vulnerable. It usually appears in spring and fall when the weather is cool and humid. The spores can travel by air or water and will quickly damage flowers.
The best way to prevent this fungal infection is to monitor humidity and maintain good air circulation around your orchids. Dispose of any affected flowers, and pick up any fallen debris that could be infected.
Plants infected with black rot have black formations and stripes.
Black rot is caused by Phytophthora fungus, which travels by water. Infection usually results from bringing in an infected plant and water splashing from one plant to another. If a plant is infected, immediately move it away from other plants and treat it with a fungicide.
Infected plants will develop large swaths of black on the leaves. Any infected leaves should be removed if there is any hope of saving the plant. The prognosis is usually fatal for young plants. Some more established plants can survive the pruning and may come back.
Root rot, the primary killer of orchids, often is fueled by excessive watering.
Root rot is the #1 killer of orchids. I’ve mentioned the dangers of overwatering, and I can’t stress enough that an orchid’s roots should never sit in water. Root rot will manifest as dark brown, mushy roots that fall apart when handled. You may not notice it until the leaves begin to yellow.
Bringing an orchid back from a progressed state of root rot is extremely difficult. The best treatment is repotting. Remove the orchid from its container and gently shake it loose from the potting medium. Try to keep the roots as intact as possible, although those already severely rotten should be removed. Dust the roots with sulfur or cinnamon to control the fungus and repot. Be more conservative with watering for a while, and your orchid may come back.
Orchids can be intimidating with their complex environmental needs. Oncidium orchids, fortunately, are less sensitive to direct sunlight, which makes the task of striking the right balance easier. However, the fragility of their roots creates a new complication, so watering is the key factor with these orchids.
The brave gardener, equipped with a little knowledge and a lot of patience, will be greatly rewarded by the oncidium orchid. These small orchids are big bloomers, and as most varieties also have a fragrance, they have a lot of wow factor when they bloom!