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.

The Orchid a book by Lauren Gardiner and Phillip Cribb, a beautiful book with 40 botanical prints

 

This book is my birthday present to myself.   Why I brought it?  Because its beautiful.  The authoritative text is the frosting on top of the cake.  Along with the book there are 40 botanical prints.  The orchids in the prints are described in the text.  The prints are suitable for framing. 

Myrmecophila culture: Why my plant won't bloom? A checklist of possible causes

The most common question I get asked about Myrmecophila orchids is “why won’t my plant bloom?” I have decided to make a checklist of the reasons Myrmecophila might not bloom. This will help guide you to find the way to make your plants bloom. 

1. Is the plant adult sized? Myrmecophilas are plants that in the wild live in a symbiotic relationship with ants that live inside their hollow pseudobulbs. These ants fertilize the plant with their feces. Plants in cultivation that don’t have ant colonies might become stunted and never reach adult size. So the first thing is to get an ID the plant and check on the size of an adult pseudobulb. If the pseudobulbs are smaller than the reported size for the species they you need to make sure you fertilize this plant with a high nitrogen fertilizer and give it plenty of water when it is producing new pseudobulbs. 

 

2. Is it getting enough sunlight? Myrmecophilas are not plants that bloom in shady spots. They will grow well, and might eventually produce a large clump of pseudobulbs. But they will not bloom. If a plant is an adult and is not blooming, the next thing to check it if it is getting the level of light it needs. I have seen Myrmecophilas growing quite well in places where they get full sun for most of the day. Personally, I put my plants close to the shade cloth, I grow them under a shade cloth that allows most of sunlight to come through. The best plants I have seen were grown with full exposure morning or afternoon sun, but protected from the midday sun by shade cloth or the canopy of a tree. 

 3. Is it in the proper location for blooming? Myrmecophilas are often planted on trees with dense canopies. This keeps the plants in shade. They will grow well but not bloom. A friend had a massive plant of Myr humboltii growing in a citrus tree. It had never produced a single flower. A hurricane severely damaged the canopy of the tree, allowing full sunlight to reach the Myrmecophila. As a result, the plant bloomed. 

 4. Is it receiving the care it needs at the critical time in its growth cycle? Most people I know affix their Myrmecophilas to a tree and that is that. No watering, except for rain, or fertilizing, except what it gets naturally from the tree or from ants if they have colonized the plant. This is a hit or miss approach. Some plants will grow well and bloom, other will rarely bloom and some will never bloom. I have seen Myr humboltii and Myr exaltata growing on the stems of palm trees doing well and blooming. I have seen a massive plant of Myr humboltii under the thick canopy of an avocado tree, with no evidence of it ever blooming. You need to observe your plant, and when it is producing a new pseudobulb, give it the watering and fertilizing it needs. 

 5. Is it healthy? Some Myrmecophilas are attacked by a type of fungus that kills their stems and primordial buds. You can tell this because part of the stem that should be green look like cork. The sad thing about this is that often nothing can be done. The warning sign is often that the plant is not producing new growths. The fact that the rest of the plant can look good even if it has lost all its capacity to produce new growths, and can remain looking good for years, is a confounding thing. Plants like this will not bloom ever. On occasion an older side bud will produce healthy new growth. But if a plant has not produced new growths after a few years, it is probably a lost cause. 

 6. Is the plant getting the proper nutrition? Sometimes you can do all the above things and still a plant won’t bloom. Sometimes a few extra things can give it the push it needs to bloom. I have used a dilution of Epson salt to give the plants more access to magnesium, in particular those that are growing in full sun and look yellow. A fertilizer with a high nitrogen concentration is recommended when the plant is producing new growths.

Myrmecophila brysiana culture: The free spirit

Myrmecophila brysiana When I received my plant of Myrmecophila brysiana from an online vendor, it was a tiny thing on a 2 inch pot. I made a custom-made wire basket for it. The plant spent the next few years producing a line of increasingly large pseudobulbs that were tightly clustered. So far everything was unremarkable. Last year, I noticed that it was producing its largest pseudobulb yet, but it was growing sidewise, into the side of the basket (large red oval). I made a hole for the pseudobulb to grow through. A few months later I was startled to discover it was producing a new growth, downwards directly into the media (red circle). I had to remove most of the media in the basket, as well as one side, to allow the new growth to enlarge and expand to full size. Then a few weeks ago, It started a third new growth, this one points straight up (small red oval). Given that the plant seems determined to grow in all directions at the same time, I will eventually let it hang from a wire and grow in whichever direction it wants.

Myrmecophila grandiflora culture: The well behaved one, that stays, mostly in the basket

When I brought this plant, many years ago, I decided to put it in a basket. I have other Myrmecophilas growing on trees, I wanted to be able to bring the plant into the house when in bloom. I put the seedling in the middle of a custom-made basket, with big chunks of bark. The plant has been growing in the basket for many years. It has been producing closely set pseudobulbs in a pattern that has been slowly growing around what was the body of the basket. I have had to remove parts of the basket to allow its pseudobulbs to grow out. Even though I used the most durable kind of media I could find for this plant, it has been in the basket for so long that all the media decayed and was washed away. The plant is now growing on its old dried pseudobulbs and roots. You can see in the photo the old hollow pseudobulbs. The inflorescence of this plant is quite tall, so if I put the basket on the floor, the flowers can be enjoyed at eye level. This plant needs heavy fertilization and plenty of watering when producing new growths. Failure to give this plant the fertilizer and water it needs in this part of its growth cycle will result in stunted pseudobulbs that won’t bloom. This plant is hung close to the shade cloth so that it gets the brightest light. I only move this plant when the inflorescences are developing. I use long hanging hooks, so that the inflorescences don’t scrape against the shade cloth and become damaged. When the inflorescences are growing, I take care that they don’t get tangled with the other baskets that are also hanging from the top of the shade house. This is also a problem with other genera that produce long inflorescences such as Encyclia.

Encyclia culture: Some notes on root initiation

One of the most important events in the seasonal cycle of Encyclia is root initiation. It At this time of the year, in early February I am expecting my plants to start growing their inflorescences. Most of my plants finished the growth of the new bulbs at the end of last year. A few, are doing their own thing. Encyclia Borincana started producing a new growth for an old, small pseudobulb, a newly brought Encyclia alata is showing new growth. A few roots with green tips can be seen here and there. This pseudobulb of Encyclia Renate Schimdt (Enc. Orchid Jungle x Enc. Alata) decided to produce a massive growth of roots. Locally, it is the start of the dry season, not a time I find desirable for a plant to increase its water needs to nurture root growth. But you got to do what the plant needs. Because I grow my orchids outdoors this mass of delicious, tender green tipped roots is a very tempting target for insects and other critters. To stop the roots from becoming food, I give the plant a spot application of a systemic insecticide. Systemic insecticides tend to concentrate on new growths, making then inedible to any insect that might be tempted to nibble on them. Protecting the roots at this stage is vital for the future survival of the plant. The loss of the root system of its newest pseudobulb can severely set back an orchid and might even endanger its survival. Note the length of the green part of the root. A very short green tip is not a good thing, it means the plant is not getting enough water. the lenght of the green in this orchid shows it is getting the right amount of watering to promote good root growth. Root initiation in many types of orchids is not like other plants, it can only happen a specific time of the year. So when it happens the plant has to be given the care it needs to produce a strong system of roots capable of sustain the next year growth, there will not be a second chance. On some instances a plant whose lead growth is damaged will produce a secondary growth a bit back in the stem, but that doesn’t always happens. Observing the long-term growth pattern of my Encyclia I have noted that they tend to rise slowly raise they stems away from the media. After a few years the pseudobulbs are sitting on a mass of roots a few inches tall, rather than directly on the media.