Dendrobium orchids, also known as bamboo orchids, are fairly easy-going orchids for growing indoors (or outdoors if you live in a tropical area).
This orchid species contains over a thousand diverse species, many of which have different needs in terms of sunlight, water, and nutrients.
Most dendrobiums rise from cane-like pseudobulbs, which are basically thickened stems that store food, water, and nutrients.
Dendrobiums are native to southeast Asia into Australia, and native species can be found from the cold mountain heights to arid deserts.
Because they are native to the Southern Hemisphere, they’ll bloom in winter in the Northern Hemisphere.
Many are epiphytic plants, which means they grow in treetops, not in soil. Because of this, they should be grown in orchid potting media that consists of a light mixture of bark with a little horticultural charcoal and perlite.
The dendrobium orchids you often see in commerce in the United States are often the phalaenopsis-type dendrobiums, named because their flowers resemble the ever-popular butterfly orchids or phalaenopsis. These have flowers in all kinds of different colors.
Some flowers are even fragrant!
When choosing a dendrobium, look for:
Thick, green leaves with no hint of insect or disease damage.
Multiple plump stems (pseudobulbs) in the pot.
Pseudobulbs are thick and not wrinkled or withered.
A nice big plant in a little tiny pot is ideal.
Understanding their native habitat can help you understand the kind of care that these unique orchids require.
Watering Dendrobiums
During spring and summer, as their new leaves unfurl, dendrobiums need lots of water. The best way to water them allows them to hearken back to their life in the treetops during monsoon season. Place the pot in the sink and run tepid water through the pot, letting it drain for a minute. Don’t use salt-softened water or distilled water.
Once the growth matures in fall, ease back on the water, letting the top of the potting mix dry before watering again. The pot should not stand in water because that is bad for the roots that need air and moisture.
Generally, a big dendrobium in a tiny pot will need to be watered twice a week, especially if the temperature is high or it’s blooming.
How Much Light Do Dendrobium Orchids Need?
They enjoy a lot of bright light, about 2000 to 3000 footcandles’ worth, but they will get burned by sustained direct sun. (A little is fine.) If you’re growing them inside, give them the bright south window. Even then, they would love having a supplemental grow light to give them all the light they can’t get from the sun.
They can be grown in lower light, but blooms are sporadic. A simple full-spectrum LED light will bring out the flowers.
Humidity for Orchids
Tropical and subtropical orchids enjoy 50 to 70 percent humidity during their growing season. However, humidity this high could destroy the rest of your house, so 30 to 50 percent is a better level.
There are a few easy ways to raise the humidity for orchids:
Growing your plants together in a group will keep the humidity high.
Set your plants on a tray filled with pebbles, and fill the tray with water to the level of the pebbles. This allows the water to drain out of your orchid pots while adding humidity to the air.
Use a spray bottle to mist the plants.
Place the room humidifier near them.
Grow them in the bathroom where they can enjoy humidity more often.
There’s a drawback to super-high humidity among plants that are crowded too closely together – this can also lead to fungal diseases. If this is the case, keep a small fan running near the orchids to keep air circulating.
Keep Temperatures on the Warm Side
Dendrobiums generally do well with daytime temperatures between 70 and 90 degrees, while night temperatures should drop (if possible) to the low 60s. If you live in a cold area, keep them away from the window to avoid leaf chill. Sudden temperature drops will also cause their buds to fall off.
Dendrobiums can do fine with being fertilized a little bit every week, and they can do fine without much of it.
Dendrobium orchids hate being repotted, to the point where some will dramatically croak over it. Generally, though, they’ll simply stop growing and blooming if you put them in a larger pot.
Repot them every two or three years when a brand-new baby shoot starts growing from the base of the plant. Give them fresh growing medium, and tuck the roots into a small pot that’s just big enough to hold everything. Sometimes roots will come out of the top pot, but let them.