How to Plant, Grow and Care For Dendrobium Orchids
Have you decided to add a Dendrobium Orchid plant to your indoor or outdoor garden? These interesting orchids can display beautiful blooms when they are properly cared for. In this article, gardening expert Melissa Strauss explains everything you need to know about growing dendrobium orchids, including their maintenance and care needs.
The dendrobium genus is an exceptionally large genus with a great number of species. The exact number varies according to sources, but there are at least 1,000 separate species of these beautiful orchids. Dendrobiums are known for their fast growth rate and abundance of flowers when in bloom.
They are able to bloom most any time of year except for winter when they are dormant. Some species are deciduous and drop their leaves in the winter. If you aren’t expecting your orchid to shed its leaves, this can be quite unnerving. However, this is a normal habit of many dendrobium orchids.
The genus is native to Southern Asia and the South Pacific, where it grows in trees in jungle climates. Dendrobiums like fairly warm temperatures, except during their resting period, when they need a bit of cool weather to perform their best.
Dendrobium Orchid Overview
Plant Type Perennial Epiphytes
Season Spring, Summer, Fall
Pests Mealybugs, Aphids, Thrips
Exposure Bright Indirect Light
Diseases Root Rot, Collar Rot, Petal Blight
Plant Spacing Individual Containers
Planting Depth Shallow
Soil Type Bark Mix
Species More than 1,000
Native Area Asia
Height up to 2’ tall
Plant with Palms and Succulents
Hardiness Zone 9-12
Watering Needs Once Per Week
Attracts Pollinating Insects
Dendrobium orchids have a few different traits. First, they are epiphytes, which means they can grow on trees. They have a sympodial growth habitat, which means they grow from pseudobulbs horizontally.
Dendrobiums are also deciduous, which means they lose their leaves during the winter. They are the only type of orchid to do so.
Dendrobium orchids are perennial epiphytes. Perennial refers to their indefinite lifespan and habit of blooming yearly. All orchids are perennial and can live for decades if given the proper care.
Dendrobium orchids are also epiphytic, which means that they grow in trees, with their roots exposed to the air, making them, essentially, air plants. Epiphytes need a lot of air circulation around their roots and are able to take in most of the water and nutrients they need from the air.
Dendrobium orchids have a sympodial growth habit. All orchids grow along a central rhizome or main stem. Sympodial orchids have a rhizome that grows horizontally, sending up pseudobulbs.
Each pseudobulb produces leaves and a flower spike, and after the flowers fall, the pseudobulb is considered spent, meaning it will never again produce flowers. However, these pseudobulbs continue to support new growth using their stored water and nutrients.
Some dendrobium orchids have the unique characteristic of being deciduous. They are the only orchids that lose their leaves and go dormant in the winter. As a result, they need a bit of cooler weather in the winter in order to set buds.
Dendrobium orchids have a similar flower formation to phalaenopsis orchids, so much so that there are species that are considered ‘phalaenopsis dendrobium’ orchids.
The three sepals of a dendrobium bloom are narrower than the petals in many cases. The two prominent petals are larger and rounded in phalaenopsis dendrobium varieties. Some species have five uniform petals and sepals.
The labellum tends to be conspicuous, frequently appearing in a different color than the rest of the flower. Most of the dendrobium orchid’s labellum are slightly funnel-shaped.
Dendrobium orchids produce long flower spikes and can produce them at most any time of year and in any number, depending on how much new growth has been produced during the year. Each spike holds many flowers, and many of these flower spikes hang down from the body of the plant.
There are several ways to propagate a dendrobium orchid. While we will discuss growing orchids from seed, this is a very long and tedious process that is not typically undertaken by home gardeners.
The word keiki is the Hawaiian word for baby. An appropriate name for this type of growth on an orchid, keikis are not new pseudobulbs, but rather, they are new plants that grow directly from the canes, stems, or a dendrobium orchid.
These tiny plants can be cut from the parent plant and will grow their own root system. It is beneficial for the parent plant to remove keikis as well, as they can draw nutrients away from the formation of new growth and flowers.
To remove a keiki, cut the stem an inch below the node that is nearest the keiki close to the base. Cut the stem above the node that appears just past the keiki. Pot this in a porous potting medium, and it will become its own plant.
Division is universally the easiest way to propagate orchids. For sympodial orchids, remember that the rhizome runs horizontally. To divide the orchid, simply cut through the rhizome in a manner that leaves several pseudobulbs on both sections.
It’s very important to always use clean, sharp tools when cutting orchids. Orchids are very susceptible to fungus and bacteria, and these can be transmitted by using tools that have not been properly cleaned. A clean cut heals the fastest.
Once divided, simply repot both divisions, and they will continue to produce new growth. The new plant will be an exact replica of the parent.
Growing orchids from seed is a tedious and time-consuming process. Orchid seeds are incredibly small and store no energy of their own.
If you have ever cut into a vanilla bean, you have seen first-hand just how tiny these seeds are. A single pod holds millions of these tiny seeds that are not only small but they are also extremely vulnerable to bacterial and fungal infections.
There are two ways to germinate orchid seeds. The way it happens in nature, which is very difficult to duplicate, and a more practical but no less time-consuming method called flasking.
Orchid seeds have no endosperm and, so no energy of their own. In their natural environment, these tiny seeds attach themselves to mycorrhizal fungi, which are able to break down the nutrients that orchid seeds need to germinate. In this way, the seeds have a symbiotic relationship with the fungi.
Duplicating this process requires a sterile laboratory environment, which most home gardeners do not have access to. For that reason, I will move on, and not bore you with the details.
This method is one that just about any determined gardener can carry out at home with a lot of patience and a clean, sterile environment. The absence of fungus and bacteria is very important when undertaking germination of orchid seeds, as they are so small and vulnerable.
Asymbiotic germination is done by a method known as flasking. The reason for this name is that the seeds are placed into a glass bottle or flask with a nutrient-dense material that is bioavailable to the seeds for their use.
The bottle is then closed to keep out bacteria, and the seeds are given time to germinate and begin their journey to maturation.
While this is a potential way for the home gardener to grow orchids from seed, it takes a very long time and requires quite a bit of patience. When an orchid is propagated by division, you could have flowers within a year. This is not the case with growing orchids from seed.
The seedlings will need to remain in the flask for a long period, up to two years, depending on the genus. Orchids are slow to mature, although dendrobiums do mature faster than many types. Even though they mature faster, it will still take up to 5 years to grow an orchid that is ready to bear flowers.
Growing Dendrobium Orchids
Dendrobium orchids are a great choice for a first-time orchid grower and a delightfully easy orchid to grow for the experienced orchid collector. These plants give back a lot of flowers with minimal effort as far as orchids go.
Dendrobium orchids are less sensitive to temperature than most orchids. They are known to grow in a diverse range of climates and elevations, from hot, humid valleys to cool, dry mountains.
They are very adaptable, and except for times of freezing temperatures, they are able to survive outdoors for much of the year in most places.
If you live in zones 9-12, growing orchids is about as easy as it gets. An orchid in these climates can be tied to a tree with an old pair of nylon stockings. The nylon breathes and allows for good air circulation, and by the time they deteriorate, the orchid is firmly rooted to the tree.
North of zone 9, all orchids will need to spend a period of the year as houseplants. Whether you keep your orchids indoors year-round or just in the winter, there are some environmental details that need attention if you want to keep your orchids happy while indoors.
The epiphytic nature of dendrobium orchids means that they need maximum airflow around their roots. It is important that your potting medium can drain completely between waterings and not remain damp for very long. Standard potting soil will quickly cause orchid roots to rot, and that is nearly always a death sentence.
Specialty orchid potting mix is sold at most places where plant supplies are sold. These mixes consist of ideal proportions of different materials that allow for maximum airflow.
If you like to mix your own potting medium, start with two parts bark chips, and add 1 part charcoal and 1 part perlite or sponge rock. Coconut coir will also work as a substitute for bark.
Most orchids are sold in bloom and potted in a medium that is predominantly made up of sphagnum moss. This is fine for the orchid while in bloom, as the flowers will use the extra moisture. Once the flowers fall and the plant goes dormant, it is important to repot with a more breathable medium.
In addition to a breathable potting medium, orchids should be planted in containers that are made to allow plenty of airflow. There are three standard types of containers made specifically for orchids.
Hanging orchid baskets do a great job of mimicking the natural environment of an orchid. These wooden containers have wide spaces between wooden slats that are joined at the corners. This allows water to flow freely through the potting medium and not pool in the bottom which can lead to soggy roots.
This is my preferred type of pot for outdoor orchids, but it can be messy indoors as the slats are wide, and potting mix regularly falls through when watering.
Terracotta orchid pots are a great option for indoor orchids. These look like standard terracotta pots, which have the feature of wicking water away from the roots of a plant. Terracotta pots made for orchids will have extra drainage holes in the sides and bottom.
Specialty ceramic orchid pots are the most attractive option, but they lack the ability to wick water and commonly come with dishes attached to the bottom. It’s very important to keep your orchid’s roots from sitting in water.
Planting depth is less important than potting medium and container. But, in general, a dendrobium orchid should be placed in its container with the oldest growth against one side of the pot.
This gives it room to continue its chosen direction of horizontal growth. Fill in around it with a potting mix and use wire or orchid clips to hold the orchid in place until it has rooted.
Dendrobium orchids like a lot of light. They will do fine with direct sunlight in the morning but need protection from the afternoon sun. An east-facing window will provide the ideal amount of sun for these plants.
If you have a window that gets sun all day, you can compensate by hanging a sheer curtain to filter the light or by placing the orchid in a spot where the sun can’t reach it in the afternoon. As long as they get plenty of indirect light for most of the day, dendrobiums will be happy.
Dendrobiums tend to be fairly tall and substantial orchids. Their root system is small compared to the amount of plant that it supports. For this reason, dendrobiums need to be watered more frequently than other orchids.
The general rule for watering orchids is once a week, letting the potting mix dry completely between waterings. Dendrobium roots will need to absorb a lot of water to support their stems, leaves and blooms, so watering twice a week is better for these orchids.
These guidelines apply to indoor orchids. If your dendrobium is kept outside in the warm months, prepare to water it every 2-3 days. Water evaporates faster in that summer heat. The most important thing is that you give plenty of water at each watering and that excess water is able to drain from the container.
Climate and Temperature
Dendrobium orchids have an ideal daytime temperature of 65°-75°F by day and about 10° cooler at night. Keep this in mind when choosing a location, as it can be cooler or warmer near a window than the temperature in the rest of your home.
More important than temperature is humidity. Orchids like a lot of air circulation and humidity. The combination of these is important for the health of any orchid, and dendrobiums are no exception. Dendrobiums like a humidity level between 40% and 70%.
I find my sunny bathroom window to be a great place for my orchids in the wintertime. The humidity tends to be higher in the bathroom than in other rooms in the house.
You can also raise the humidity level by using a humidifier, or, if you’re concerned about this doing damage to other items in the home, a tray of water placed under the orchid pot will provide humidity as the water evaporates. Just be sure to place some stones on the dish to elevate the pot never let the roots sit in water.
Orchids like to be fertilized regularly during their growing season. Specialty orchid fertilizers are great, but if you prefer to use an all-purpose fertilizer, any balanced fertilizer such as a 10-10-10, diluted to ½ strength, will work just fine.
Fertilize once every 1-2 weeks during the growing and blooming season. That means that nearly every time you water, you will fertilize. Every three weeks, flush the potting medium with fresh water to help with salt buildup.
Fertilizing can be decreased to once monthly in the winter when dendrobiums are dormant.
Maintenance & Pruning
If your orchid is potted correctly and in the right atmosphere, short of watering and fertilizing, it will not need much maintenance otherwise. Orchids do not need to be repotted unless they are outgrowing their container.
Orchids do not require regular pruning. It may be tempting to remove spent pseudobulbs, but it is important to leave them intact until they are dried out and brown. These structures continue to support the plant until they are drained of nutrients.
After the flowers fall from a spike, you can leave the spike to dry out on its own, or you can encourage more flowering by cutting it off. Starting at the base of the stem, find the first node and cut the spike one inch above this node.
There are a few different popular varieties you’ll likely come across. Let’s look at the three most common/popular varieties that you’ll likely encounter when choosing one for your home garden.
|botanical name Dendrobium Farmeri
|sun requirements Bright Filtered Light
|hardiness zones 9-12
‘Farmeri’ is a gorgeous type of dendrobium that grows in Southeastern Asia, in tropical jungles. The plants can grow quite large over time and produce multiple flower spikes. Each spike is completely covered with stunning flowers.
The flowers are a pale mauve pink color, with a bright yellow labellum and white accents. So many of these flowers grow on a spike that the stem is completely occluded.
|botanical name Dendrobium callista Jaquelyn Thomas ‘Uniwai Mist’
|sun requirements Full to Part Sun
|hardiness zones 9-12
This variety is a pretty phalaenopsis dendrobium orchid that was hybridized in Hawaii. This Nobile-type dendrobium likes for its roots to be a bit cramped. It sends up long-lasting sprays of delicate white flowers. These blooms are fragrant and can last from 6-8 weeks.
‘Uniwai Mist’ can bloom more than once per year under the right conditions. It likes a sunny window and regular fertilizing.
‘Little Sweet Scent’
|botanical name Dendrobium HonoHono ‘Little Sweet Scent’
|sun requirements Part Sun
|hardiness zones 9-12
This stunning, semi-deciduous orchid is another Hawaiian native. The plant drops its leaves from old spikes before it blooms in spring. The blooms are just delightful. This purple orchid has delicate pale purple petals and sepals surround a darker purple, funnel-shaped lip.
The lip has a velvety appearance, with tiny hairs covering the exposed portion. This orchid is known for its wonderful raspberry fragrance.
Pests and Diseases
Orchids are beautiful, fascinating plants when they are healthy… sadly, there are a number of insects that enjoy munching on their tender new growth, and some leave behind very undesirable side effects.
The best way to prevent orchid damage from pests and diseases is to keep watch over your plants and pay attention to any damage as soon as you notice it. Inspect all new plants brought into your environment. Prevention and good plant hygiene are the best defense against most pests and diseases.
These little green and yellow insects are a great thorn in the side of many gardeners. Aphids can cause a significant amount of damage to an orchid in a fairly short amount of time.
Aphids feed on the sap of a plant’s tender new growth. They will attack new leaves and buds, stunting the growth and destroying the blooms. They also leave behind a sticky excretion that causes mold to form, further damaging the plant.
Aphids typically enter the environment on infected plants. Inspect all new plants for these little bugs. If you discover aphids on a plant, isolate it and treat it with an insecticide until there are no traces of the insects before reintroducing it into your home.
Thrips are a very difficult issue to diagnose due to their small size. It’s possible to see their damage and not be able to diagnose it because these little guys are good at hiding.
They suck the nutrients out of your orchids and leave significant damage, particularly to young plants.
The best way to detect these bugs on a flowering plant is to tap a flower and watch the center interior of the bloom. If there are thrips present, they will be jostled and run around a bit. Isolate, treat with neem oil or insecticidal measures, and do not reintroduce the plant until the pests are gone.
These little white bugs have a fuzzy appearance, and they are very hard to get rid of. Mealybugs reproduce quickly and leave a trail of destruction in their wake, first draining the plant of sap and nutrients and leaving a sticky excretion behind that attracts ants and can play host to sooty mold.
If you spot these little critters, immediately isolate, treat, and repot, disposing of the old potting mix as they can live in there as well. It is nearly impossible to treat these insects without insecticides. Mealybugs do have plenty of natural predators outdoors though so moving the plant outside can be helpful.
As far as garden insects go, scales are some of the worst. They reproduce very quickly, and can deplete a plant of nutrients, causing severe damage. It is difficult to treat scales because of how quickly they reproduce, so more than one treatment is always necessary.
If the infestation is very small, use a q-tip soaked in isopropyl alcohol to wipe the insects away, be careful, as overuse can damage a plant. Neem oil can also be effective. Repot and dispose of old potting materials to give your plant a fighting chance against this nuisance.
As with all of these insects, the main culprit is usually the introduction of an infected plant. Be sure to inspect all new plants and buy from familiar sources.
Also known as petal blight, botrytis is a fungal disease that tends to prefer orchids over other plants. It travels by air and likes cool, damp environments, so it is mainly an indoor, wintertime issue,
Botrytis attacks the soft tissues of an orchid, particularly the buds and flowers. Initially, it shows up as small brown spots on blooms but can quickly kill a plant if not treated quickly.
Fungicides can be effective, but the damage can’t be undone, so remove damaged tissue, and your plant will need some time to recover and produce new growth. The best treatment is prevention. Maintain good airflow and isolate an infected plant right away.
This disease is caused by a waterborne fungus that is most often transmitted through improper watering habits, such as allowing water to splash from the leaves of one plant to another. The fungus comes in on a new plant, generally, and spreads by way of water droplets bouncing off leaves.
First, black rot will show as black or purple spots on new growth, and eventually, it will spread to old growth and cause entire leaves to turn black and die. You can treat it with fungicides and remove all affected tissue to give your orchid a chance at recovery.
Overwatering, which causes root rot, is the single greatest killer of orchids. If an orchid’s roots wit in water or remain damp for long periods of time, they will begin to soften and degrade, which lets in bacteria and fungus, causing the roots to rot and ultimately causing whole plant death.
The best solution to this is prevention. Once root rot appears as yellowing leaves, it is difficult to rescue a plant. Dividing and repotting can help. Make sure to remove all affected root tissue and dust the remaining roots with a fungicide such as sulfur or cinnamon. Adjust your watering practices to help your orchid produce strong new roots.
Dendrobium orchids are wonderful, easy to care for, and beautiful. They make great starter orchids, and if you’ve had difficulty with more finicky orchids, they may help you make a comeback and learn the ins and outs of orchid care.
These hardy orchids like plenty of sun, and they can tolerate more watering than other orchid genera. Overall, dendrobium are sturdy plants that produce tons of gorgeous flowers as a reward for proper care and keeping.