Dendrobium stratiotes Rchb. f. 1886

 

In my experience, this Dendrobium does well and its easy to grow in Puerto Rico.  Once the canes have reached mature size, they will produce long lasting flowers.  The canes can vary in size depending on the genetics of the plant and the care it receives.   Sadly, I lost it because I became too complacent about its care.  The thing is, once the cane reaches the side of the pot, its a must to repot it taking care to damage the roots as little as possible.   Neglecting repotting can cause the loss of the plant once the roots that are in the pot die. 

Dendrobium culture: Dendrobium cucullatum, getting the plant to produce really long canes

 One of my favorite Dendrobium has been Dendrobium cucullatum, also known as Den pierardii, and Den aphyllum.  This species does well in my climatic conditions, so much so that all you need to do is attach it to a tree and it will grow and bloom with little care.  I have had plants of this species for many years.

In photos of this plant in Asia I noted that the plants were in many cases much thicker and longer than my plants and produced more and larger flowers.  After observing my plants, I concluded that the issue was that the plants were in baskets and pots that dried too fast for this species.  As a result, a plant that could potentially produce a six feet cane, would top out at a third of that size.

To rest this hypothesis, I put a three-cane plant of this species in plastic soda bottle that was cut in a way that there is a water reservoir at the bottom of the bottle that the roots of the orchid can reach.  I also made holes that allowed plenty of air to reach the roots, this is to avoid rot.

The results were highly gratifying.  The plant produced a five and a half foot cane, much thicker than usual.  In the second year in the pot its on its way to produce an even larger cane.   This year it bloomed with many flowers, sadly marred by thrips.  I expect that next year it will produce even more flowers.  I have a nasty surprise prepared for any thrip that might show up to eat the flowers.

In the future, I plan to make a basket that will allow for four or five canes to grow together.   Given the large size that such an arrangement would achieve the basket and pot would need to be quite strong not to be turned upside down by the sheer weight of the canes.

On a final note, the size of a plant is influenced by many things, light, fertilizer, watering, genetics, temperature and others.  It may be that some plants of this species are naturally small.  The plant I used for the test came from a parent that I knew can produce at least six foot long canes and maybe longer if given optimal care.  So don’t be frustrated if you plant doesn’t suddenly becomes a giant.

Dendrobium culture: Observations on the color of the mature canes in some Dendrobium species when exposed to strong light

Many Dendrobium need high light to bloom at their best, but the way they respond to it varies depending on the species.  My Den. nobile blooms with larger flowers with richer color when the canes are getting so much sun that they take a yellowish tint.   On the other hand, the Dendrobium primulinum from Laos produces larger flowers when the canes are exposed to full sun and turn purple.    Den anosmum doesn’t change color too much even when exposed to full sun, perhaps the canes are just a bit lighter green color.  I haven’t noticed a color change in the canes of Den devonianum, but the flowers of my plant which is exposed to full sun for hours in the morning show very pale color in the sepals and petals, so pale that it can make one think the flowers are not of devonianum unless one looks closely.  My newly acquired plant of Dendrobium ceraula shows a deep purple tint on the side of the cane that receives the sun and green on the side that is under the shade of the leaves.  In my experience Dendrobium cucullatum becomes yellowish and stunted if exposed to too much sun.   

Dendrobium culture: A shade house for Dendrobium anosmum

Dendrobium anosmum needs exposure to full sunlight to bloom well.   But too much sun burns the plants.   I build this wooden shade house so that I could grow my plants in a place where they got the right balance of sun/shade.   The shade house was oriented so its longest axis was perpendicular to the sunrise in the spring/autumn equinox.   It was eight feet tall so that the long canes of the Dendrobiums could hang down without touching the ground.  It was 10 feet long and four feet wide.  To shield the orchids from the harsh midday sunlight a camo fabric was used.   In places I also used black shade fabric.  Notice the camo fabric has a multitude of holes.  This made a pattern of sunlight and shadow that moved across the plants during the hottest parts of the day.   The desired effect was to achieve something similar to the way sunlight is naturally filtered by the leaves in the forest.

 But the key thing of the shade house was its open sides.  To the east of the shade house there were few trees, so the Dendrobium and other plants would get full strength sunlight from about 8 am to 11 am.   The west side of the shade house faced the closed canopy of the forest, so after midday, the plants were in the shade.   This mimics what happens in the natural habitat, where a plant that is growing in the side of a tree can get plenty of sunlight during part of the day and its on the shade after that.

 I used to have many of plants of Den anosmum.  So many plants that when the shade house was full, I could grow plants that needed lower light levels under the Dendrobium.    I hung the Den anosmum in the east side of the shade house and in the center of the structure, these were the areas that received the most intense sunlight for the longest time.   Under the Dendrobium, in the ground I grew Phaius, Calanthe, Phaiocalanthe, Cymbidium, Paphiopedilum, Vanda and Angraecum.   The shade was narrow to maximize the plants exposure to light while protecting them from the midday sun. 

 During the rainy season, in the afternoon the sky would get cloudy and it would rain, this would reduce the intensity of light in the afternoon.    But in the dry season there would be very sunny days, uninterrupted by any clouds, and this threatened the plants with sunburn, even those that were in their resting phase.  To avoid this, I would put a few old dry palm fronds on the roof of the shade house.  This reduced the level of light to tolerable levels.

When the Dendrobium were ready to bloom, they were moved to the terrace.  You can see the result in the photo below.

The wooden shade house was destroyed by a tropical storm.  It was rebuilt, much stronger, now made of two inch metal pipes.  This one lasted until Hurricane Maria dropped the top of a Teak tree on it.

Dendrobium culture: No, its not dead.

For most orchid growers nowadays, Phalaenopsis are the gateway drug to bigger and more expensive plants.  But the Phalaenopsis that are now widely available are the product of many decades of hybridizing toward producing a plant that will survive in the average home even when (shudder of horror), watered with ice cubes.   Orchids species are an entirely different beast.  With 30,000 species (at least) species orchids show growing patterns and seasonal cycles very different from your average hardware store Phalaenopsis.   That is why it is important to read about the plants you buy.  A lot of orchid growers do impulse buying and then are bewildered by the way their plants react. 

 An example of a plant that can confuse a novice grower that is trying species is Dendrobium devonianum.  It produces slim canes that can be almost a meter long.  Unlike the leaves of Phalaenopsis, the leaves of Den. devonianum are slim, delicate and are soon deciduous.   During the growing season a cane of this species has leaves near the growing end of the cane with the rest quite bare.   When the cane stops growing, it eventually sheds all its leaves and for months afterwards it looks like its dead.    If the canes have been exposed to strong light and have developed a purplish color, they can look even worse.

This is an adaptation to the cold dry season when the trees lose their leaves and it rains little.  The orchids then have to endure months of drought and harsh sunlight.   My plant blooms in April, just before the local rainy season starts.  For months it looks like a mass of dead and shriveled stems.   But this is deceptive.  In the nodes of those leafless stems the flower buds are maturing.  A well flowered plant is quite impressive.

If you look at the top photo, the orchid looks like its in a wretched condition, ready to be thrown into the trash can.   But if you look closely, you can see the remains of many inflorescences in the second longest cane.   Note the very small root ball.  That is not unusual, if a plant is well fed and watered it will produce just the minimum of roots it needs to fill its needs.   In the bottom photo you can see the cane covered with flowers.

Dendrobium anosmum var.huttonii, 2023 growing season, plant in wire basket

 

The best performing of all my Den anosmum huttonii plants is potted in a home-made wire basket.  The wire basket is five inches deep and four inches wide.  It looks small for an orchid that is several feet long, but it is the best option for me since this plant is growing outdoors and gets soaked almost every day during summer and fall which is the time of the rainy season.  The plant has been growing since February and still have four months to go to finish its growing season.   The plant has some keikis that I have kept on the plant so they will be larger and stronger when they are removed next year after the plant blooms.  During the peak of the rainy season, it rains so much that the media can become coated in patches with white fungus.  In a pot this would be really, really bad for the plant since the fungus accelerates the decay of the media and interferes with the capacity of the roots to absorb water.   But in the basket, the roots still have access to moisture and oxygen in spite of the fungus.  With the onset of the dry season the fungus dies out.   Normally this type of fungus is kept in check by the daily cycle of drying that the media experiences every day.  But during the rainiest days of the year, the media can remain wet for weeks or months even in the baskets. 

This orchid is growing so well I plan to move all my other var. huttonii to baskets.   Because some of my plants are grown in the north coast of Puerto Rico which is drier and windier than my current location, I plan to grow them in plastic pots with a small water reservoir.  I will try this because in the coast the winds dries the media in the baskets much faster than in the mountains.

Dendrobium Culture: Making a Den cretaceum specimen plant

 

Some years ago, I started cultivating a Dendrobium cretaceum plant with the aim of eventually getting a specimen plant with many flowers.  For aesthetic reasons I decided to cultivate the plant so that the canes hang from the bottom of the basket.   The orchid is planted in a way that is extremely different from what is the usual way of growing Dendrobium.   The plant was originally attached to the center of the bottom of the basket.  That way the roots would grow up into the potting mix and the canes would grow downward.   That is the exact opposite of how these plants are grown.    The basket is six inches wide and three and a half inch deep.  The potting media is bark, and fills the basket to a depth of two inches.   Den cretaceum is not a big plant so this arrangement allows plenty of space for it to grow for years.

There two-inch layer of media in the basket allows for plenty of air to reach the roots.   This is a very important detail.  You would think that is a very small quantity of media for a plant that one eventually wants to become large and bushy.  But due to the local climatic conditions it is the perfect amount.  The reason is that during summer and fall in my locality it rains almost daily.   At the peak of the rainy season the media can stay wet for weeks or months.   In a plastic pot this would mean a waterlogged media that would quickly become devoid of oxygen, will start rotting and turning into slush under the influence of fungi, bacteria, high temperatures and fertilizer.  

 To my delight, at the start of the 2023 growing season the plant, that usually produces four or five new canes every year, in a fit of exuberance, started producing nine new canes.   This is wonderful but it bring its own suit of problems.   First, all the canes are clustered and oriented toward the strongest source of light.   That means that the plant is self-shading.   This can result in that some of the canes will be spindlier and weaker.   To avoid that I moved the plant to a spot where it gets the strongest sunlight I can give it without burning the leaves.  Eventually as they grow the canes will spread out and the issue will resolve itself.  Because of the particular way the canes of Den cretaceum grow the leaves are not particularly vulnerable to burn if exposed to strong light.  The canes of this orchid arch downward, so that when the sun is at its strongest the leaves are edge on to the light.   A note of warning, while canes are capable of taking full sunlight, the base of the canes are prone to burning if exposed to very strong sunlight.  Fortunately, this is not a problem for me since the basket protects the tender bases from the sunlight.

If all goes well, by the start of the 2024 dry season, the canes will have reached their full size.  When the canes reach full size, I stop watering and fertilizing the plant, it gets only the scant amount of rain we get during the dry season.  The plant loses all its leaves and looks dead for a time.   In April I will start looking for the swelling flower buds along the length of the canes.  Then in May I expect the plant to produce a mass of flowers.  You can see on top the 2023 blooming.   The plant as it is now is in the photo below.

Dendrobium anosmum var huttonii

I have cultivated this particular clone of Dendrobium anosmum var. huttonii for many years. It has several peculiar traits that make it distinct from other anosmum plants. But first let’s mention which trait defines var. huttonii as a distinct variety of Dendrobium anosmum. The defining trait of var. Huttonii is a pure white flower with purple color on the lip. If a plant has any color, no matter how pale, outside the lip, it is not Huttonii. There are many, many named varieties of anosmum, but only two have been scientifically described, var. dearei, the alba form and var. huttoni. The other variants, and there are probably dozens or even hundreds of them, get their names from commercial growers or from informal descriptions in popular literature. To mention just a few, anosmum from the Philippines sometimes are called superbum, also there is var. delacourii, var. velutina (both very hairy flowers with flowers that look squashed), “touch of class” and the “thai” type. Also, there are many hybrids of anosmum and parishii, cucullatum, primulinum and rhodopterygium that are sometimes sold as anosmum. Hybrids sometimes sold as anosmum are Nestor, Supernestor, and Little Sweetscent. There are several traits that are characteristic of this huttoni clone. For example, my plants start producing flower buds and showing basal growths in the middle of January. A six to seven weeks before the type form of the species does the same in my locality. The clone I have is less vigorous than the type form of the species. It takes dedicated care to coax this plant to produce canes more than two feet long, and none of my plants have produced canes larger than three feet. It is common for anosmum to produce plantlets near the tip of old canes that have lost their roots. Huttonii produces plantlets near the tip of canes, but it also produces them, at the middle of the cane. Huttonii plantlets separated from the mother plant will tend to remain small unless they get fertilized regularly during the growing season with a fertilizer that has a high nitrogen number. In December, I reduce considerably the water my plants get and they start shedding their leaves. By the end of January most of my plants are entirely leafless. My huttoni bloom from leafless canes. Normally, anosmum plants produce their flowers along the length of the cane. If the only few flowers are produced they tend to cluster at the tip of the stem. In huttonii, the flowers can appear near the tip of the cane but also at random spots near the middle. Sometimes small plants will bloom if they have several canes. I have seen plants with canes that are less than eight inches long produce a single flower at the tip of the cane. The huttonii clone has never been as floriferous as the type form which can produce dozens of flowers if well cared for. I am happy if any of the canes produce eight flowers simultaneously. Sometimes a cane will only produce two to four flowers. And here is the most bizarre thing about this clone, sometimes a cane that bloomed early in the year will bloom again, weeks or months after it first flowered. No other anosmum variety I have has shown this peculiar trait. The flowers are highly fragrant. When this plant shows the buds of the flowers and the new growth, I return to a normal watering and fertilizing schedule. I cultivate my plants in baskets because during the rainy season it can rain heavily, every day for months. This, and the heat and the insects tend to turn most organic potting media into slush in a bothersome short time if the media stays saturated all the time. Baskets allow for fast drainage and at bit of drying in between rain events. This also means that the media can get very dry during the dry season and will need several good soakings before it starts retaining water. These plants are heavy feeders and will not grow to a good size unless regularly fertilized. At the beginning of the growing season, I remove the plantlets from the older canes. Sometimes I cut a sizeable section of the cane around the plantlets to them a better head start. The critical part is the time period when the plantlet is sending into the media the roots of its first cane produced after separation. If anything happens to the roots, this will be a considerable set back to the growth and will endanger the survival of the plantlet. A plantlet that is well cared for can start blooming as soon as two years after being separated from the mother plant. There is more information on the culture of Dendrobium anosmum elsewhere in this blog.

Dendrobium devonianum Paxton 1840

 I brought this Dendrobium last year.  One of the few orchids I have brought after hurricane Maria.   This plant has been delicate and lost two canes to rot during the rainy season.   However the youngest cane survived.  The cane is just a fraction of the size of the older ones it had when it arrived, but to my surprise it produced flowers.  Not many but I don't complain.   I have read Dendrobium devonianum is quite variable but I was puzzled when the flowers started opening.  To me it seems as if someone grafted the huge lip of Den, primulinum of a devonianum flower.  I have never before seen a Den, devonianum with such huge yellow dot and without purple on the distal tip of the lip.   Hopefully, next year the plant will be larger and stronger and will produce even more of this beautiful flowers.   The flowers are strongly fragrant in the afternoon.

Dendrobium uniflorum Griff. 1851

Seen at the US Conservatory, in Washington DC, on July 2019.

Den. Ueang Pheung (Den. jenkinsii x Den. aggregatum) cultural notes

This hybrid is the product of the cross of two similar especies.  The species are so similar that some consider them the same species.  Dendrobium (aggregatum) lyndleyi produces long inflorescences of yellow flowers.  Dendrobium jenkinsii produces one or two flowered inflorescences of relatively large flowers that can rival the size of the cane that produced them.  The culture for both species is identical.   I decided to grow this plant in a wire basket instead of the usual tree fern trunk due to the fact that the warm and wet weather of my locality tends to speed the bacterial decay tree fern to such an extent that in a few years. if it is subjected to a steady stream of fertilizer, it becomes soft and begins to break down.  

The only differences I have noted between the hybrid and the species Dendrobium lydleyi is that the species needs a stronger, longer exposure to the sun to bloom well.  And that the species will sometimes bloom poorly if it is watered during the coldest driest part of the year.

Culture: 

Light: Bright light, a few hours of full sun in the morning, but the plants are protected from the midday sun.  The rest of the day it is shaded by trees. 

Temperature:  In my climate, the temperatures are the lowest in February when they go down to 14 C.  From June to October the high temperatures are 32 C.  The plant grows well in this range.

Watering: The plant is watered every three to two days, when the basket is approaching dryness.  It is only watered in the dry season, the rest of the year the local rain pattern gives it enough water to sustain growth.

Fertilizer:  It is given a 20-20-20 fertilizer but only if it is showing new growths.  When the plant starts a growth cycle, a small quantity of manure is put over the potting material.

Potting:  In a wire basket, in medium bark.  

Dendrobium discolor Lindley 1841, 'Karlo Javy' AM/AOS, this plant has a particularly nice color. It was awarded last March in Puerto Rico

Dendrobium purpureum Roxb. 1820

Cadetia taylori [F. Mueller]Schlechter 1912, considered a Dendrobium

This plant was photographed in March 2019, at the 70 annual show of the Puerto Rico orchid society.

Dendrobium anosmum var. huttoni

In the difficult weeks and months after the hurricane, I lost hundreds of plants to the changed conditions of illumination, humidity and rainfall.  This is one of the survivors of hurricane Maria.  Last year it was in poor shape and it didn't bloom.  The 2018 canes were small for the plant but they were large enough to produce four flowers.  I expect that as it recuperates from the damage it suffered after the hurricane it will go back to blooming well.  It is highly fragrant and even with only four flowers it perfumes the area around it.

Dendrobium harveyanum Rchb.f. 1883, blooming late in the year, months out of its normal blooming date.

Hurricane Maria caused grievous damage to the forest where I live.  Many trees fell and the canopy was destroyed in most of the forest.  Humidity and rainfall dropped.  Because there was no canopy the area temperature went up.  Also without the canopy the full power of the tropical sun hit all the understory plants burning them severely and killing some.  I lost many of my orchids to the changed environmental circumstances.  But some survived through it all.  Among them Dendrobium harveyanum.  In the last month it has not rained and the plants are suffering.  I wonder if this period of low humidity triggered this out of season blooming of the harveyanum.

Dendrobium sutiknoi P.O'Byrne 2005

I photographed this plant at the 2018 Puerto Rico orchid society orchid show.  This Dendrobium is a big plant.  The flowers are impressively large for an antilope Dendrobium,

Dendrobium primulinum (now known as Den. polyanthum)

These photos are of a flower that that was just opened.  The flower will expand a bit in the first few days after it opens.  Dendrobium primulinum is a variable species with a vast geographica distribution, but all its forms share the characteristic of a lip that is almost round and very large in comparison with the rest of the floral segments.

Dendrobium nobile culture: Growing naturalized in a tree in Aguadilla, Puerto Rico

I brought this plant back in 1990, at that time it was huge, it completely filled an twelve inch basket with its canes.  I got it from a plant vendor that had been growing the plant for years without it producing a single flower.  Although the plant was large, the vendor gave it to me very cheap.  The vendor was happy to clear bench space for more profitable plants and I was happy to have a plant to experiment what conditions would make it bloom.

In December, I took the plant with me to the place I lived at the time, at an altitude of of 3500 feet, in the Sierra de Luquillo, in the eastern part of the island of Puerto Rico.  The local temperature in winter can go down into the upper fifties and the local humidity is very high often in the nineties.  I put it in a place where it would get morning sunlight but would not get rained on.   Then I didn’t water it for two months.  Because of the high humidity the canes didn’t get very shriveled and wrinkly.   In March of that year I started watering it sparingly, in April I started watering it normally but didn’t give it any fertilizer.

In May of that year the plant was covered with buds.  When it bloomed, it produced 150 large, fragrant flowers.  It was quite a spectacle.    When the plant finished blooming I took it out of the basket and divided it in many pieces.   I gave away several the pieces, potted some, put some in baskets and tied a piece to the trunk of an avocado tree.

The plant in the avocado tree grew slowly.  Mainly because I left it completely alone, no watering or fertilizer.  It has been in the tree now for three decades.  At first it was in deep shade, and it would not bloom even when the canes were fully adult sized.  Then part of the tree was cut down and the plant suffered sunburn, it bloomed weakly.  Now that it gets full sun in the morning and dappled sunlight the rest of the day it is blooming better than ever.  The canes are the largest it has ever produced, some are two and a half feet long.

The flowers are fewer and larger than the plants that are potted and get watered and fertilized.  The color of the flowers is variable.  I have observed that the plants that are in full sun have flowers with more intense color.

This plant has a very wide temperature tolerance and can even endure temperatures close to freezing without harm.   From my experience, I can attest that it is a good plant to naturalize on trees on those areas that are not subject to freezing weather.  Although I have some plants on pots and on baskets, none is as large or as healthy as the plant naturalized on the tree.  This is mainly because they must be repotted from time to time and this means they lose some of their root ball.  The naturalized plant has a massive number of roots that cover the trunk for a few feet around it in all directions. 

However, this plant might not bloom even with the best of care, this can be caused by a number of reasons.  First, if grown in a spot that is too shady the plant will not bloom, it will produce long and spindly weak canes.   If given fertilizer at a time when it is finishing its growing and getting ready for the dry season this will stimulate it to start new growths and can short circuit the blooming season.   If watered at the time when it is normally the dry season in its habitat, this also can inhibit blooming.  Some plants can bloom in the shade, even if fertilized and watered, but often they produce just a few flowers near the tip of the canes.  Low temperatures stimulate blooming in this species.  The plant canes can lose their leaves during the dry season, this is normal and a prelude to blooming.  I should add that I have seen fully leafed canes blooming.  But generally, it has been my experience that plants that keep their leaves bloom less abundantly than those that become deciduous.

Dendrobium purpureum Roxb. 1820, can grow to be expectedly large, this is the typical form.