Dendrobium anosmum (or superbum – as in “superb”)

September 13, 2014 by Ric Fieler 5 Comments

My Den anosmum from Spring 2013

Dendrobium anosmum is a pendant type (soft cane) deciduous orchid that grow native to Malaysia, Laos, Vietnam, Hong Kong, Philippines, Indonesia, and Papua and New Guinea. Anosmum is a misnomer. It’s a Latin word meaning “without scent” which is actually quite fragrant. This flower, at least mine, has a fragrance I equate to raspberries. In the Philippines they refer to the fragrance as repulsive. Maybe it is repulsive in large quantities – such as when the Melaleuca trees bloom en masse along the Turnpike in Miami. Last year my anosmum had 100 flowers with an enjoyable but not overwhelming fragrance you could enjoy throughout the patio.

Like most orchids the anosmum is an epiphytic orchid–it grows in trees. It does not grow in dirt. If planted in dirt, or if its roots are left in water, it will die from lack of oxygen. In its native habitat the roots grow on the surface of the bark of the trees. The roots need to dry between watering. That isn’t too much of a problem here in Florida, especially if you water early in the morning. The Florida temperature typically ensures that it dries out before night. But the plant should not be watered late in the afternoon or evening since the roots will tend to stay wet, which could accelerate mold or other microbe growth that could damage the plant.

I grow many of my orchids in clay pellets. I find the clay holds water for a short time, as well as retaining nutrients when I fertilize, which will allow the roots to slowly absorb the water and nutrients. But the clay dries out faster than most other planting media.

My anosmum from spring of 2014 with keiki’s

In the wild the stems can get to be 6 feet long, but potted plants usually only get to be 3 feet. My plant is only 20-22”. In their native setting the plants will start to grow new stems at the beginning of the monsoon season, which coincides with the rainy season here in Central Florida. They like a lot of water during the growing season, which starts when the plant begins putting out new growth, and ends when the new leaves stop growing and start to turn yellow. (Growing season is usually March to October). At the beginning of the season you should water the plant once or twice a week and increase watering as the plant gets larger and the summer temperature increases. Sometimes I will water my anosmum a couple of times a day in the hot summer and fertilize every week. Near the end of the growing cycle (September) you might start to reduce watering to only once or twice a week.

If you grow the plants outside they will probably get all the water they need from our tropical rains. If for some reason we go several days without rain, you might want to give them a good drenching of water from the garden hose. I have several of my orchids hanging in my oak tree which allows them to benefit from the rain and keeps them protected from the noon sun while still getting a lot of indirect light.

Orchids need light, but it should be a bright diffused light. Never let them be exposed to direct overhead light from the mid-day sun. This could burn the plant, which will stunt it’s growth, reduce its flower yield, and could possibly kill the plant. The plant can be grown inside but will need to be near an east or west window. This will allow it to have early morning or late afternoon sunlight. Do not put it in a south facing window or anyplace where it will get direct mid-day sun.

Near the end of the season, around September, the stems will start to get too heavy and begin to lie down. It is best if you can hang the plant a little crooked, so all the stems lean over one side of the pot. This will provide the best showing for the flowers.

Den species keiki’s growing in sand

At the end of their growing season, October/November, you should stop watering the plant. It is best to bring them inside your house, or at least under an eave, to prevent them from getting rained on. In their native lands, the rains stop and many of the trees lose their leaves along with these orchids.  If you keep watering the plant they will keep growing and will typically not flower. And in the spring, instead of producing flowers it will develop keiki’s at the nodes of last year’s canes.

Also in its native habitat, the sun’s angle is lower in the sky so they still get light but it’s not a harsh light. Sometimes I put these orchids in the garage or inside the house, where there is not much light at this time of year. They seem to do just fine even with low light levels.

Here in Central Florida, we can still get cold weather. These orchids like a little cold. Cooler temperatures stimulate the plant to flower in the spring. But don’t leave them outside if it’s going to get below 40 degrees. This could damage the plants.

By October/November they should have lost all their leaves and the bare stems will be hanging alongside the pot looking like the plant is dead.  Trust me, it’s not. The canes (pseudobulbs) are full of stored energy, plenty for producing flowers and new growth in the spring.  If you have the plants inside your home over the winter, and you turn on the heat, you may want to buy a water bottle and give the plant a gentle spritz every week.  This will make sureit doesn’t dry out too much. In its native habitat, the air is cool and drier but it still has some humidity. Home heating systems can dry the air out a little too much for these plants.

Keiki’s before potting

When the weather starts to warm up and the fear of any cold fronts is past, usually by late February, you can move the plant outside. When new plants start growing from the base of the old stems, you should start watering moderately at first. Sometime in March or April, you should start seeing small growths on the old stems near the spot where the leaves were growing (before they fell off). That is the flower bud. As the flowers start to develop you can give the plant more water, but do not give them any fertilizer yet. Wait until the flowering stage is complete. Fertilizing could burn the flowers.

Fertilizer: You can buy orchid fertilizer at Lowe’s or Home Depot. I find it works best to put the fertilizer in a small spray bottle and soak the plants. Do not fertilize more than once a week. In fact it probably wouldn’t hurt them to go two weeks between fertilizing. Some people mistakenly believe that more fertilizer will make the plants grow faster or better. This is counter-intuitive. Orchids are not like other ornamental plants. They’re not terrestrial. They grow in trees. They get their fertilizer from composted bird droppings and decayed leaves that get washed across their roots. If they get too much fertilizer it will either burn the roots, which will prevent them being able to transmit water and nutrients to the plant, or give the plant so much fertilizer that it will grow long and spindly instead of compact and healthy. Orchid hobbyists have a saying about fertilizing: “weekly weakly” which means once a week with a weak fertilizer solution.

Den anosmum keiki’s potted up spring 2014

Let me say something about air circulation. These plants do not like stagnant air. They prefer to have a light breeze just above them, which will help keep them dry between waterings. But they don’t like to have a fan directly on them either (this is a concern if trying to grow them inside, under a vent). Drier plants have less problems with mold and bacterial infections.

Most orchid hobbyists tend to grow their plants in a greenhouse, where they can control all these factors: water, fertilizer, light, temperature, and air circulation. One day I hope to have a greenhouse (or two . . . or . . .). This also helps with the control of pests. I currently grow most of my orchids on my patio, and as many as I can on low branches in my backyard oak tree hanging from teacup hooks. I have great admiration for orchidists who grow their plants inside. Although I know one in Canada who grows all of his Catasetinae orchids from South America inside; although  I guess you have to grow them inside when you’re in permafrost.

If all goes well you will be rewarded with multiple 2-inch purple flowers with a sweet fragrance similar to raspberries.

Den anosmum. Large specimen (not mine)

But . . . the plant I gave to my friend Zohair is still young.  It may be two or three years before it flowers. There’s a possibility that one of the larger plants may have one or two flowers. This plant is actually several “keiki’s” from my plant.

A keiki is a plant that grows asexually from the parent plant. After the stems produce flowers. the stems still have energy left to produce more plants. They use this energy to help the next growth especially when there isn’t enough water or fertilizer in the wild for them to grow. But orchidists make sure our plants have plenty of water and fertilizer. So after the flowers have wilted and the current new growth is large enough, I will sometimes cut off the old dry stems and lay them in wet sand, making sure to keep them damp. After some time, new plants will start growing at the nodes where the flowers were produced.  When the roots are about 2 inches long I remove them and put 5 or 6 into one pot. The potted plant I gave Zohair is actually several keikis from the mother plant from this past year.

Since these plants are so young they may not go through a full cycle. So there’s a possibility that the plants will not go dormant but will retain their immature leaves through the winter. Sometimes they will lose their leaves later in the cycle.

Den anosmum flower (Mine)

People think it is hard to grow orchids. It’s actually pretty simple. Give them some water, but not too much. They also need fertilizer, but don’t overdo it. They need light but not too bright. Also not too hot or too cold – just the way Godilocks would like it. If all else fails just stick them out in the trees and let Mother Nature take care of them. Oh, wait, one other rule: not all orchids require the same care. Pretty easy huh? Good luck.

My plant was given to me by a friend, Hugo, as a keiki from his plant. Now I’m giving a kieki from my plant to my friend Zohair. In a few years Zohair should have a plant healthy enough to grow some keiki’s so he can pass on to his friends and family. Who knew orchids could be so contagious.

Note: I gave one of my keiki’s to a friend, Zohair, who is new to orchids. I wanted to give him some information and care, and decided to publish it on this blog. This way anytime I give one of these orchids to another newbie, I can just direct them here. These are just my observations and I found these work best for me. I’m sure there are others who might have different opinions on culture and care for this species. I would be happy to hear any comments or questions. BTW. You can click on the pictures to enlarge.