Svante Malmgren         Henric Nyström

Orchid propagation

The web pages will give you a clear view of the methods involved in propagation. They can be used by individual enthusiasts, for scientific research or for conservation projects in the wild. Presented are the ”state of the art” procedures with their current possibilities and limitations. There are descriptions of a number of species and hybrids that are suitable subjects for the garden.

Sadly, there are still people who lack respect both for nature and for the law and who dig up and sell wild orchids, even those that are rare and protected. Unfortunately, the Internet has made such illegal activity easier, but with a little knowledge about what is possible with different species, one can get some idea of the legal status of plants offered for sale. Hopefully, by making propagation methods more widely known, illegal trade will decrease. Growing and promoting selected orchid hybrids will have the same effect.

The propagation of orchids from seed is achieved on sterile media. It can be done with the help of a symbiotic fungus (mycorrhiza) added to the medium at sowing time. Nowadays, though, new and extremely simple growing media that are effective in the absence of a fungal symbiont – asymbiotic propagation – have simplified procedures so much that the symbiotic methods involving fungus will probably disappear outside research laboratories. Nobody has attempted to use mycorrhizal fungi to propagate tropical orchids for many years. Asymbiotic propagation can be done using just your own kitchen as a laboratory. A pressure cooker is the most expensive item in which you need to invest.

A sterile nutrient medium replaces the materials that the fungus supplies to the small, growing embryo in nature. In the relevant literature, long, complicated recipes can be found containing minerals, vitamins and plant hormones measured out in exact quantities, sometimes as tiny as fractions of a microgram. The inspiration for these comes from ”conventional” micropropagation techniques, where details are very important for the growth and proper differentiation of small in vitro plants. Such recipes rarely work for hardy orchids, however, and for practical purposes extremely simple media can be used with success. The fine detail of the ”scientific” formulae reflects the hitherto common belief that orchid propagation from seed must be an exact science and that nothing else is possible. The problem might seem complicated at first sight, but its solution does not have to be!

Svante Malmgren has so far successfully propagated approximately 200 different orchid species and hybrids (he lost count 12-15 years ago when he passed 100). In the vast majority of cases, reproducible methods have been developed for large-scale production. It must be understood, however, that certain species remain tricky to grow. Poor germination rates and less than perfect growth on media still trouble the work, but ongoing trials are likely to solve the outstanding problems. In addition, some orchid genera and species have not yet been tried at all. Challenges remain, therefore, for future generations of orchid growers.

For all the species and hybrids described on the website, you can start out from the following simple recipe:

Ca3(PO4)2 50-100mg
KH2PO4 50-100mg
MgSO4 50-100mg
Sucrose 10-15g
Activated charcoal 0.5-1g
Tap water 1,000g
Agar 4-5g

Either Vaminolac(t) (= an amino-acid solution equivalent to approx 300mg amino-acids)

Or 150mg NH4H2PO4 plus 100mg NH4NO3.

Some species grow better on amino acids, some on inorganic nitrogen. Details will be given on the other pages.

It is not necessary to be exact when weighing out.

A complex organic ingredient, the most important component, is added.
Suitable additives for orchids from temperate climes include a small piece of potato, turnip (swede) or banana. Alternatively, coconut milk or pineapple juice may be used. In some cases a combination of two produces better results. Apparently, these complex organic substances contain plant hormones and unknown growth factors that benefit the orchids in a way that exact formulae containing well-defined plant hormones do not. Many years of trials by several different workers lead to this inescapable conclusion. Using such additives may be more of a pragmatic than a scientific approach to orchid propagation but the proof of its efficacy cannot be doubted. Thousands of little orchid plants can be produced and, of course, fruit and vegetables are significantly cheaper than plant hormones!

Different species require different complex organic additives and different quantities of them. For success, you must choose the correct additive(s) and be accurate in measuring the amounts that you add. For some species, half or double the quantity could severely compromise growth and be the difference between life and death for the little orchid plants! This observation is rather surprising; conventional plant hormones used in propagation do not produce the same degree of sensitivity and similar changes in concentration do not have the same deleterious effects.

If you get the medium correct, though, you can achieve a 90% germination rate and excellent growth with a very large number of species and hybrids.

The pH value should be about 5.5 – 6.0, but with the given components this is the pH that you usually end up with anyway if your tap water is fairly typical. When pineapple juice is used, its pH must be adjusted with NaOH, or preferably aqueous ammonia to approx pH 6. It is prudent to prepare your pH-adjusted pineapple juice in advance. It can be stored in the freezer, a method also well suited to storing small pre-cut pieces of potato and turnip (swede).

Sterilisation is done in a pressure cooker or autoclave at 120º C for 20 minutes. The sowing vessels are used soon after the agar gel has set. Very soon the agar gets harder and more difficult to work with.

Seed sowing requires very specific treatment of the seed, which varies depending on the species. Despite its small size of 0.1-0.2mm, each seed has a thin seed coat that is impermeable to water. This has to be broken down chemically. The seed must also be sterilised, of course, before sowing, and the two requirements can fortunately both be satisfied by the same procedures. Treatment with NaClO (sodium hypochlorite) solution will sterilise the seed and in many cases will also degrade the seed coat. The concentration of the hypochlorite and the duration of the treatment must be adjusted according to the thickness of the seed coat, which varies from species to species. Suitable concentrations range from 0.3 to 1%, and the treatment time from 5 to 45 minutes, depending on the species. Too short a bleaching time will be inadequate to sterilise the seed; too long a time will kill it. In order to break down the seed coat in some species sequential treatments with sulphuric acid and hypochlorite are necessary. Some species must have a post-sowing cool treatment of 3 months before they will germinate; other species will germinate after only 2 or 3 days.

Additionally, there are species, especially some Cypripediums, whose seed has to be sown half-mature in order to make it germinate and grow-on successfully. In such cases the entire, green seed capsule is sterilised in concentrated NaClO and/or alcohol and the seeds are sown directly from the opened capsule onto the medium.

Assessing the correct maturation time of the immature seed is difficult. An interval of only 4-6 days separates seeds that are too immature to germinate from those that are too far advanced! In Cypripedium, the correct stage is reached 7 –10 weeks after pollination, depending on the species. Weather conditions too can speed up or retard seed maturation… maturity comes much quicker during a warm summer.


Using the correct seed treatment, however, a germination rate of 50-100% can be achieved from the mature seed of most species and hybrids. There are 500-1,000 seeds in a capsule of Orchis militaris, 200-500 in that of an Ophrys and about 4,000 in one from Cypripedium flavum.

When new hybrids are created, the necessary seed treatment corresponds to that of the mother plant. Genetics are not always symmetrical!

Practically all species within the genera Dactylorhiza, Gymnadenia, Platanthera, Nigritella, Coeloglossum, Ophrys, Serapias, Himantoglossum and Anacamptis pyramidalis can be propagated asymbiotically on a large scale. Several, but not all, Orchis species are also fairly easy to propagate. A large number of Cypripedium species and hybrids are relatively easy, and problems with the remainder are being solved as time goes by.
 

We have tried Epipactis and Cephalanthera from mature seed on a very few occasions with poor results, but not total failure. Lack of time is often a limiting factor for the orchid propagator. Further growth on medium continues for 8-15 months usually, depending on the growing rate and this differs from species to species. Replating onto fresh medium is done just once, most often 2-4 months after sowing. When the plants start to develop leaves they should be provided with weak light. The young plants do not need strong light and too much will cause undesirable heating of the culture vessels.

A priori, it is tempting to believe that solely the chemistry and components of the medium would – if it is suitable – produce normal little orchid plants. Then we have forgotten the importance of the growing temperature, or rather, the temperature sequence over the year! Although being grown totally artificially on sterile medium, the little orchid protocorm and plant still have demands and expectations on growing temperature, for normal development, just like adult plants. In some cases a chilling period is neccessary for germination, but for several more species a chilling period correspondingly to “normal winter” is neccessary at a certain protocorm size, in order to induce normal shoot and root formation “in springtime”. Details of this in different genus and species are given on the other pages of the web-site. In many species a period of lower temperature is not neccessary – but beneficial for further growth. So, the medium can be said to be the motor of propagation, but the temperature sequence is the steering-weel!

Planting out into soil is best done when the young plants are in dormancy. With Orchis, Ophrys and similar genera small tubers that form in the medium have just ripened in the late spring or early summer when they should be potted up. Orchids akin to Dactylorhiza and Cypripedium can be removed from flask as well grown plants in cool but frost-free conditions between late autumn and early spring. They can also be kept in the flasks, cool over winter, and potted very early spring. There is much practical benefit in following the “natural yearly clock” of the species and in planting out at a time when dormancy occurs in nature. This, of course, means that seed must be sown at the correct time of year to meet this requirement. Mediterranean Ophrys produce mature tubers on medium 7-10 (-12) months after sowing. Some central European Orchis species need a cool treatment during their development and mature after about 15 months – others need just 8 – 10 months. Time of sowing must be adjusted to the predicted growing time, or rather what you have found out empirically earlier years.

The mycorrhiza, if needed at all in the adult plant, never seems to influence success at the planting out stage. Guide books and scientific reports provide complex compost recipes and methods for adding fungi to the soil mixes, but mycorrhizal fungi are abundant in natural soils, and such procedures are unnecessary. The young plants might recruit a natural fungus from the soil when first potted up but perhaps they just don’t need one. We generally use soils obtained from natural habitats that appear suitable for orchids. We have two sources, one from a limestone area and one from neutral sandstone. Pots can be crowded with small de-flasked plants and the soil can be recycled every year. This means that Mediterranean Ophrys, Swedish Nigritella and one-year old American and Chinese Cypripediums all grow in the same soils and we encounter no problems.

Recently a scientific study has been done, at the Univeristy of Agriculture at Uppsala, Sweden. The mycorhiza was isolated and identified from roots of Nigritella nigra in county Jämtland, Swede. Isolates were done from “wild” plants as well as from atrificially propagated and re-established plants on similar localities. In both cases the same fungus could be identified. The findings are in no way surprizing, there are lots of fungus to choose among for the orchid plant in a suitable habitat!

We have also experimented with potting up Cypripediums in multi-purpose compost designed for indoor plants with added cow manure (!) and the plants grow excellently, escpecially 2^{nd year in soil..}

Myths and much repeated dogma surround the suitability of different soil and compost types. With increasing experience, common garden sense will replace the incantations of complex soil reciepts. In reality, no more than standard gardening problems are involved. If the soil is too hard, add a little sand; if it is too dry add a little peat. Some species prefer lime-stone soils, others prefer slightly acid soils. Some need a dry resting period in summer, others prefer a well-drained but never dry soil.

In the year following potting-up the plants are very tolerant of situation and survive well outside in the garden if a little thought is given to the suitability of the soil type and position. Alternatively they could be planted out in a suitable natural habitat. The soil from the pots is recycled.

Flowering occurs 3-5 years after sowing, depending on the species or hybrid. Further information may be found under each described genus. A few examples of Orchis and Ophrys can flower two years after sowing; in their first year on soil.

In the garden, only certain species can be grown. In the wild many orchids are bound to specific habitats and some may therefore be unsuitable for general horticulture. There are many hybrids, however, that are very easily grown and deserve much wider recognition. This is not strange. Most plants found in a modern garden setting are selected strains and hybrids and the time has come to extend this situation to the hardy orchids.

The ability to propagate these orchids opens up new possibilities in the field of scientific research. Genetics and systematics could benefit from a new approach and plant physiology and population studies can adopt novel methods.

Conservation projects can be undertaken on a large scale and populations of rare and threatened species enhanced or saved from extinction. The interest for this type of approach appears to be low in Sweden and Denmark and this seems to be mainly due to the attitude of the influential professors and botanists, who regard nature as no more than their own scientific playground. Amongst their peers it seems to be regarded as a greater achievement to report a species’ demise than to do anything to prevent it! The dominant frame of mind encourages only preservation, not intervention.

Compare this with the many avian conservation projects that involve breeding programmes (“propagation”) for eagles, falcons, horned owls and the like that no one opposes! 99.8% of all ornithologists are happy, involved amateurs who receive neither monetary reward nor scientific award for their work. Bird species are actively conserved by the drive and dedication of these people.

One exception to this narrow-minded approach in Scandinavia is “Project Nigritella” in the county of Jämtland in northern Sweden. Nigritella nigra has been the subject of a large WWF-supported scheme to save the species. Svante Malmgren has contributed to this project, has raised plants from seed and has re-introduced them to selected sites. Nigritella is very easy to raise from seed on medium but is a little tricky on soil and it took 8 years to flower from the time that the seed was sown!

In Denmark, in 2006, in the very last moment, a project for saving Ophrys insectifera har started. Svante Malmgren suggested that 10 years ago in an article in a Danish scientific paper.

However, for Spiranthes spiralis it is now too late in Denmark, and it doesn´t seem to be any interest at all in propagating the last few plants of Cypripedium calceolus.

Good bless the botanicians! Or maybe not?