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.

An orchid story: The Oncidium altissimum that would not bloom

When I was a college student, I was going to attend some athletic events in the capital city of Puerto Rico. I lived at several hours driving distance from the capital, so a friend invited me to stay at his house which is near where the events were going to take place, so I would not have to do a long drive.  It was the first time I had visited my friend's house.  His mother knew that I cultivated orchids and asked me to take a look at one of her plants.  She told me that even thought quite large and healthy,  inexplicably, it would not bloom.

When I looked at her orchid I was impressed, the plant was easily three feet across and had a large number of adult sized and quite fat pseudobulbs.  The plant was in excellent condition and free of pests.  I was baffled, a plant of such size in the wild should have been full of the remains of old flowering stems, which in this species can reach ten feet long.  On her plant there was no evidence that the plant had ever bloomed.

I started asking her questions and soon realized she had no idea how the flowers of the plant looked.  Actually she knew very little about the plant, only that it was an orchid, and that was that.    I could not find anything wrong with the plant or with the care she was giving it.   Then she told me that she had one problem with the plant.  There were some vine seedlings that kept invading her plant and growing on the media.  She had to continually cut them, but to no avail, they, very stubbornly, kept invading her plant in spite of her ruthless campaign against them.

When she said that, I asked her to show me from where the pesky vines would grow.  She pointed me to the bases of the pseudobulbs.  She thought that inflorescences were invading weeds!!  She didn't recognize the inflorescences of the Oncidium because she know nothing about the plant and because the inflorescences grow quite a bit before they produce the branches where the flowers are.   She had spent years cutting the inflorescences.  You might be surprised that such an absurd thing could happen, but this happened in the ancient times before the Internet, when information sources about orchids in Puerto Rico were few and you had to go to a mayor library to get even basic information on common types.

I told her about the inflorescences and how to tie them so that they would show their best.  I had to do this because the plant was growing in a large pot in the ground in an inside garden.   Eventually. the plant finally bloomed with many inflorescences to everyone's delight.

Dendrobium keiki, What causes them to appear?

Dendrobium harveyanum keiki producing a second cane, because it has substantial
roots it can be removed with little fear that it wiil die.

Keikis from unbloomed stem of Dendrobium Yellow Chinsai, probably caused
by too much nitrogen in the fertilized applied late in the growing season

Dendrobium anosmum keikis, these are tiny and have little green tissue to support
independent growth removing keikis this size is not adviced.

Dendrobium anosmum keiki, this plant has a good size for a keiki and a significant growht of roots.   It can be removed with confidence that it has enough reserves to start growing idenpendently

These Dendrobium anosmum keikl have three canes with means they are over due for removal
from the cane, the original cane has decayed completely.

Dendrobium primulinum keiki, although on the small side for a keike the fact that it has two canes
will help this plant adapt to independent living without too much trouble.

Dendrobium fimbriatum oculatum keiki.  This keiki is quite large and can be treated
right away like an adult plant onece it is removed from the cane.

One characteristic of some Dendrobium species is that they have the capacity to produce plantlets from the meristematic tissue that lies in the form of small buds along the sides of the canes of the adult plants.  Most of the year these buds lie dormant, but if they are activated by hormonal changes in the plant they can turn into floral stems or into little plantlets.  In the hobby these little plants are known as keiki, this is the Hawaiian word for baby.  I will use the term keiki to refer to this form of propagation on the rest of this article.  Keikis are plantlets produced vegetatively by the mother plant, it is an asexual type of reproduction which means that the little plants will be exact copies of the mother.

 The frequency of keiki production varies wildly in the Dendrobium genus.  Some species will never, or only very rarely produce them, I have yet to see a keiki in a plant of Dendrobium farmeri or Den. secundum.  In other cases some plants will produce keiki and others of the same species will not.  This is my experience with Den. harveyanum, one plant has produced several keiki while another has never produced them.   Some species will almost always produce one to a few keiki from older canes, an example of these are Den. anosmum, Den. cucullatum and Den. primulinum.  In the extreme of keiki production Den. crumenatum and Den. kingianum produce them frequently and sometimes abundantly. 

There are several circumstances that can stimulate the production of keiki.  A relatively common occurrence is the production of keiki instead of flowers.   Normally canes will not produce keiki in their first year, before they have bloomed.  If a mature cane produces keiki instead of flowers when its blooming season comes around, this means something has disrupted the sequence of metabolic processes that produce the hormonal changes that turn the resting vegetative buds into floral buds.  In Dendrobium descended from Den. nobile and related species, if the plant is given a fertilizer with a high nitrogen content during the latter part of the growing season or the resting plant experiences too high temperatures, this can “short circuit” the blooming response and then it can either not bloom or it can produce keiki where blooms would have been expected.    I have seen plants produce keiki all along the cane where flowers should have been.  In rare cases a plant can both produce keiki and some flowers.   A few days ago a friend showed me one of his Den. nobile hybrids where the plant had produced keikis instead of flowers and then some of these keiki had produced a single flower from the tip of their tiny canes.

In many Dendrobium species the sudden production of keiki by a plant on canes young and old is a signal of significant root loss.  I have frequently observed this on Dendrobium species from the Spathulata section and on hybrids descended from Sphatulata/Phalaenanthe section.  These hybrids are produced by the millions and are commonly sold on Walmart, Home Depot and other stores because they travel well and their flower sprays last for weeks in good condition even in hot weather.  The problem with these Dendrobium is that most the people that buy them often now virtually nothing about their growing needs.   When these orchids are repotted they are frequently put in dense bark mixes that are kept wet.  If the mix is so dense and soggy that it doesn’t allow oxygen to reach the roots, the roots die.   The one common indication that the roots have died is the complete defoliation of the plant.  That is all canes, young and old shed their leaves due to the loss of the capacity for water uptake.   By the way, it is normal for the older canes of many types of Dendrobium to be leafless, it is abnormal for a cane of the year to lose their leaves, particularly in the evergreen types that are common in the retail market.  If the plant is cared for well, it might start growing in its season and if it has a number of healthy canes it can even produce a reasonably large mature growth that will in time produce a new root system.  But if, the loss of roots has been accompanied with the loss of the lower vegetative buds, the plant can produce keiki from the top of the canes.  I have seen plants that have lost the lower vegetative buds because the owner buried the base of the stem under the potting media and the new growths have succumbed to rot.  By the way, sometimes a Dendrobium will produce a new cane from a bud that is located slightly higher in the stem than previous growths, this is not a keiki, as canes produced this way can develop normally to full size.  This sometimes happens when the buds at the base of the stem are lost.

Keiki produced at the top of the canes varies hugely in quantity and quality depending of the ancestry of the plant.  I have an antelope Dendrobium (of the Spathulata section) called Percy’s Passion.  This plant lost its roots and produced a single very large keiki that is for all purposes a small adult plant.  This keiki has even bloomed with a substantial inflorescence while still attached to its mother’s cane.  In these cases these keiki can be cut from their stem, potted and treated as an adult plant, they don’t need any special considerations.

On the other hand some plants will produce tiny keikis at the very tip of the canes.  These keiki are typically one to two inches long and depending on the parent species, can have a substantial quantity of roots or almost none.  Keikis that are smaller than two inches are a special case. They are much more fragile than those that are over two inches and might not survive being detached from the cane.  If they have few roots they will need care that addresses their particular needs and it may be more than the average grower might want to provide, also they will take a long time to reach maturity.  In my experience that hardiness and vigor of these tiny keiki vary depending on the species.  Keiki of anosmum, cucullatum, crumenatum and primulinum larger than two inches long, are quite hardy and survive very well if given appropriate care and an environment with high air humidity.  I have not been so lucky with small keikis of the Phalaenanthe section and of the “antelope” Dendrobium of the Sphatulata section.    In my experience keiki from these groups take more time to grow larger, produce roots more slowly and succumb to rot more readily.  Admittedly this is probably due to the particular environment in which I keep the keiki in my orchid growing area, some people elsewhere might have a different results.

I have observed that older canes sometimes produce keiki even in the absence of any of the issues that I have detailed previously.  My guess as to what causes this is that keiki production in older canes is probably related to the loss of the roots that are connected to that particular cane.  In these cases the plant still has a healthy root system in his younger canes and all the canes receive moisture from those roots, so this keiki production is not related to any distress from the part of the plant.  I don’t cut out these keikis until they have at least two canes and a significant number of roots. 

If a cane losses its vascular connection with the rest of the plant it can start producing keiki.  This may happen if part of the stem rots or is damaged.  If the base of the stem is buried in the media the death of the base of the stem might not be evident to the casual observer.  Also even though the cane connection to the vascular system is severed there still might be a substantial amount of dead but not decayed tissue holding the cane together with the rest of the plant.  When this happens to my pendent Dendrobium I may cut the cane in the part that has decayed and plant the keiki, still with the cane attached, in another container or mount.  This often makes a huge difference in the speed in which the keiki reaches adults size, as the piece of cane can provide, if large enough, with enough support to allow the keiki to produce a substantially larger new cane in its next growth phase.

Many growers propagate their Dendrobium using the capacity of these plants to produce keiki.   They cut the older canes into three to four node sections and lay them in sand that is kept moist.  I have seen this method producing satisfactory results with canes from “soft cane” Dendrobiums such as anosmum, cucullatum and with many of the types of the Dendrobium that are available at department stores and that are lumped in the literature under the denomination “evergreen”.

Dendrobium anosmum and their relatives, warning signs of cultural trouble

Vigorous and healthy root growth, note that the cane producing the roots is twice as thick as the previous growth

New roots are white older ones are grey green, absence of root growth is a clear signal of trouble

Fungal and bacterial infections can strike with astonishing speed and virulence, this is all that remained of a specimen plant of Dendrobium formosum var. giganteum.  If the gravity of the situation had been recognized on time at least some pices would have been saved for propagation

This Dendrobium nobile has been growing for many years in an avocado tree under hot tropical conditions.  It has never bloomed although in all aspects it is mature plant fully capable of blooming.

Dendrobium nobile blooming in a shady and cool location.

A Dendrobium phalaenopsis derived hybrid which lost all its roots due to inappropiate potting, all the old roots are dead but some new roots are showing their tips near the base of the canes.

The buds at the base of this canes are dead so the plant is producing new growths from buds higher up in the cane.

The base of these canes of Den. primulinum was damaged by sunburn and died.     The canes were bent so that the keikis produced by them can attach themselves to the basket.  Notice the many keikis and their abundant root growth.

Den. phalaenopsis hybrid grown with its roots exposed.  Note the abundant flower production and the fully leafed new cane.  It is normal for older canes to lose their leaves after the first year.

Under good care some keikis will bloom even when they are not affixed to anything

When they are growing at their preferred temperature and lighting range, well cared pendent dendrobiums grow vigorously, without any particular trouble and bloom reasonably well. But when they are grown under conditions that are unsuitable for them several things happen that serve as a warning signs that the plant is not doing well. I will detail some that I have learned from the bitterest experience. This is a work in progress and I will try to add information as time permits.

I. When your plant needs a colder rest period to bloom than you can provide.

If a plant needs a colder rest period to bloom but otherwise the conditions are to its liking you will get an endless production of handsome canes, which will be plump and healthy but will never bloom or even get in bud. Because circumstances prevent them from blooming these plants channel their energy into growth and can produce quite large plants. One Den. chrysanthum I have eventually produced a ten feet long cane. This particular plant has never produced even a single bud under the local climatical conditions. Dendrobium nobile will not usually bloom in coastal Puerto Rico but will bloom nicely if moved to locations about a 1,000 feet high in the mountain areas and in certain colder inland areas. There are plants here and there that bloom under conditions that are not in their usual preferred range but usually they do so erratically or poorly.

II. When the temperature is not in the preferred range for growth.

The first signs of trouble in this case is usually a lack of root growth. Unfortunately some pendent dendrobiums can survive for many years growing weakly and with root systems that barely sustain whatever meagre growth they manage. It can happen that the plants perk up and do produce good growth during brief times when conditions are to their liking, but as soon as temperatures drift out of their preferred range the plants weaken again. I brought a Den. falconeri that managed to survive ten years by growing acceptably during the brief weeks that local temperatures dipped and then sulking the rest of the year. Strenuous efforts to sustain this plant only lengthened the agony. Eventually the plant dissolved into a mass of tiny canes and diminutive keikis that were too weak to survive the summers heat. Keiki production on a a same year growth is also a very bad warning sign. It usually means that the plant inability to produce roots has made it transfer its energy to keiki production.

III. When it is not getting enough sunlight

If your plant is not getting enough sunlight to bloom properly you will probably get a few blooms right on the tip of the cane. A plant that might produce dozens of blooms might only produce two or three. The canes themselves might get to be abnormally long and thin. The leaves will have a deep green color.

IV. When roots are not entering the potting mix, or holding the mount.

This probably mean the mix is unsuitable for the plant because it has some characteristic that is inhibiting or killing root growth. A friend of mine accidentally killed many of his orchids by mounting them on the wood of a plant whose wood is permeated by a substance this plant secretes to kill other plants that  might compete with it for food or sunlight.  

V. A growth coming from a cane other than last years cane, if last year cane doesn't grow.

It probably means that the base of its newer cane is dead and the plant is trying to keep alive by producing growths elsewhere. In some plants, (this is an specially insidious occurrence in pendent dendrobiums) a cane that has shed its leaves can continue attached to a dead base without any obvious signs of distress for months before decay reveals that the base is dead.

VI.When a cane suddenly stops growing in the middle of producing a new leaf.

Usually means that something has severed the connection between the growing tip and the base of the plant. I have seen this happens when an insect gnaws the middle of a cane and makes a cavity but leaves it mostly attached to the base on the sides of the cane. This can cause the death of the whole cane, not just the tip.  On some ocassions this can signal a bacterial or fungal infection of a stealthy nature that only becomes obvious when the cane starts to decay rapidly at a time when it should have been growing.

VII. Blackened and sunken areas between the base of the plant and the lower part of the cane.

Can mean sunburn to this area, can result on the death of the plant but the survival of some of the canes.

VIII. Profuse keiki production on plants that normally produce them sparingly.

A sign of root loss, or of loss of the buds at the base of the plant.

IX. A weaker cane than the previous year's cane.

Plant is not getting what it needs to grow well, common in newly repoted plants that have suffered severe root loss and plant adjusting to new environments.

All this information is courtesy of the need to unwind after an unexpedtedly streesful day at work.