Comments on Coelogyne Hybrids

In my case, I set out to challenge the widespread belief repeated in books, magazines, through orchid clubs and nurseries, etc. that Coelogynes are difficult to breed. In the long history of recording plant hybrid breeding there are only 68 + Coelogyne hybrids registered and about 200 known species. There are a few simple reasons for this.

Firstly, it is necessary to own, or have access to, a variety of Coelogynes available as parents. Most people only have space for the three or four main species Coelogynes. Most of these have already been used and their hybridised off-spring registered. Not many people have extensive collections of one type of orchid - let alone Coelogynes.

Secondly, to fertilise the potential hybrid, the flowers of both plants need to bloom around the same time of year or extra complicated techniques need to be used to store pollen until a suitable pod parent is in bloom (many different species flower at different times of the year). The viability of the seed deteriorates rapidly during storage of many seeds. This process adds many complications that further frighten off hobbyists. Additionally, it is advisable to have several plants of each species because some flower earlier or later than others of the species and this range of flowering times further increases the chance of having two species flower at the same time.

Thirdly, flowers need to be a reasonably similar size to have high success rates of pollination. A small flower producing small pollen may have difficulty growing its pollen tubes long enough to fertilise the ovaries of a large flower. Coelogynes can have flowers ranging from 1cm to over 12cm in size. This can present obvious limitations in choosing partners.

Fourthly, motivation is needed to pay big dollars for laboratories to process the germination and flasking of the hybrids, or, growers need the skills and equipment to process their own. Since Coelogynes don't make the grade into the cut-flower market, there is not much commercial motivation to hybridise. Additionally, it is more financially viable for garden nurseries to stock the few well known Coelogynes that may have a higher sales turn-over. Very few nurseries stock any type of orchid, or any other plant, that doesn't have a high turnover.

Be assured that Coelogynes are not difficult hybridise. In addition to producing primary hybrids I am successfully managing secondary and complex hybrids. This is all being done in a quite crude home-based laboratory by a fairly ignorant amateur !

Intergeneric Coelogyne hybrids are a remaining future challenge. I have successfully germinated Coelogyne mooreana x Pleione formosana pods several times but have not been able to manage to keep the deflasked seedlings growing to produce a flower.. This cross could be beautiful and have enormous appeal with the inclusion of pinks and mauves. The prolific flowering Pholidotas and Dendrochilums are more exciting possibilities but there are possible difficulties due to the large differences in flower sizes.

Coelogynes are an enormously under-rated orchid and their potential has not yet been tapped. Some growers like to grow species only but even some of the existing Coelogyne hybrids are impressive flowers by any measurement, e.g. two that every grower would delight in owning are Coelogyne Unchained Melody and Coelogyne Memoria Wilhem Micholitz.

A sterile sowing environment can be created by using an upturned glass aquarium with a couple of holes cut in one side to allow the arms to get inside to work. Flasks and equipment can simply be boiled or heated in a gas flame. Everything needs to be constantly sterilised with disinfectant spray (be cautious of dangerous and flammable chemicals. The image above shows a second hand laminar flow unit. This filters organisms out of the air and provides a sterile air flow in which to work very conveniently. Next to it is an old ex-hospital autoclave unit for sterilising equipment. This is all set up in a very crude environment under my house - not in a scientific laboratory !

 You too could do this ! Bring on the future !

Media:

There is an enormous amount of misinformation, secrecy, black magic, etc. spread about germination mediums. I accept that there may be orchids that are very difficult to germinate and that it might be better to use a specialist media. However, on my Coelogynes I have been minimalist and use a simple home made mixture that includes 2 to 3 mls per litre of a liquid fertiliser based on urea and ammonium nitrate (UAN) and used on very large scale agricultural wheat and oilseed cropping. On 'Kirribilli' farm in Australia, this commercially available fertiliser is mixed in tanks of several thousand litres and applied to the soil at crop sowing time.  On the farm, this fertiliser is applied at the rate of 80 litres per hectare. You can imagine how long 1 litre lasts me! To find the rate for a flask I did some crude calculations on the surface area of a flask. I then used trial and error and basically halved the amount of fertiliser used in each batch until I arrived at a suitable amount. I used it because it was available !

My complete media recipe is as follows:

      3ml (1/2 tsp)               Urea Ammonia Nitrate (UAN)

      3g   (1 & 1/2 tsp)         Agar

      60g                             cooked banana

      1 tsp                           activated carbon (I sometimes omitted this item)

      1 litre                          hot water.

Because both the water and banana will vary in acidity/alkalinity it is recommended that you adjust the pH to around 5.6 by using the tiniest pinch of citric acid to lower the pH and make the mixture more acidic, or use hydrogen peroxide to raise the alkalinity for a higher pH. Very tiny amounts are needed and mix well before re-measuring.

I bought a 2kg container of agar and made a series of batches until I found the right consistency (slightly firm but not hard). I would repeat this testing process  if I bought a new container and I think you would need to be careful using small volume purchases as the product varies considerably.

I use a teaspoon of activated carbon per litre, mainly because I managed to get a kilogram very cheap from a hydroponics bloke. I'm not sure why I use it and often leave it out with no apparent difference except it makes the media look nice with a dark colour !!

When I get more time I will experiment with substituting other simple household garden fertilisers such as Aquasol. I suspect that they will also work in most cases once you get the concentration right.

Mixing in hot water requires a little safety care but the ingredients mix much better than in cold water.

Dry Seed Sowing

There are two basic ways of sowing orchid seed, dry seed sowing or green pod sowing. With the former method the pod has fully ripened to the point whereby the pod has split and the seed is falling out. The seed will have been exposed to the air and to all the fungus and bacteria spores around it. The seed is going to need sterilising in some sort of liquid that is going to kill the germs but not kill the delicate seed (Coelogyne seeds seem to be fairly tough compared to some very delicate orchid seeds). My technique is as follows:

1. Soak the seed (in a very small container) in one teaspoon of sugar in 100ml of water and a couple of drops of detergent for about 24 hours. Stir frequently.

2. Use a syringe to carefully remove as much of the water as possible, leaving the seed behind.

3. Add a few millilitres of 3% hydrogen peroxide to the seed and agitate it every 5 minutes or so for half an hour.

4. Remove some of the hydrogen peroxide with a syringe if possible (any remaining will be diluted with water and will break down quickly over the next couple of days). The more delicate the seeds the more hydrogen peroxide needs to be removed and the more the soaking needs to be watched.

5. Add a couple of millilitres of sterilised water to the seeds - just enough so that you can swirl them around in the solution and pick some up in an eye-dropper.

6. Use the eye-dropper to drop little globules of the water and seed solution on the media. Seal the flask and pray.

Green Pod Sowing

Many people prefer this method. It is based on picking the pod while the seed is still in the pod because inside the pod is sterile and protected from all the germs in the air. The tricks are to estimate when the seed has developed enough inside the pod to survive if the pod is cut open and the seed removed. The other goal is to move the seed from the safe and sterile womb to the safe and sterile orchid flask without contaminating the seed.

1. The pod needs to be soaked in a container of water with a couple of teaspoons of sugar and a few drops of sugar overnight. Stir as frequently as is convenient and even use an old tooth brush to give the pods a scrub. The sugar stimulates the spores into activity and makes them more susceptible to being killed. The detergent breaks down the wax coating on the outside of the pod so that the germs can be killed.  Measurements are not over critical at this stage.

2. Place the pods in a container of 5% bleach (from the supermarket) and 95% water. Clean the pod in this solution with a toothbrush for 10 to 15 minutes and it should be ready to remove from the liquid and cut open with a sharp blade e.g. scaple, in a sterilised environment such as a laminar flow cabinet or in your home-made arrangement.

3. Sprinkle the seed lightly over the media. There could be millions of seeds so resist the temptation to sow too thickly. Try and make a least three flasks so that you have some safety redundancy in case one flask gets badly infested.

4. Try and keep the flasks somewhere with a fairly even temperature in indirect light.  Ordinary flouro tubes work perfectly well for light unless you like spending lots of money on fancy ones.

Flasks

Any glass jar is fine but I like ones around 300ml and if they have a wide opening it will be easier to remove the seedlings later for movement to another flask if they are too thick or getting too big. You can spend a lot on techniques to allow the flask to breathe. A simple idea is to use the lid of the jar to trace and cut out two layers of coffee filter paper. Fit these inside the lid and screw it onto the jar.

Mould:

Mould loves growing on media in a flask. It is not good because it loves the nutrients in the media and competes very strongly with the germinating orchid seeds to the point of starving them to death.

Absolute hygiene is required to prevent contamination and even so you may still get contamination. Large fluctuations in temperature force the flasks to breathe much more than normal and can also increase the risk of spores getting into the flask.

Keep a very close eye on flasks and if a spot of mould is detected very early it can be treated in sterile conditions as follows. Open the flask in a sterile environment (e.g. laminar flow cabinet) and use a sterile spoon (or something else suitable) and scoop the mould spot out with a generous amount of the media from underneath the mould spot e.g. half a teaspoon. Using an eye dropper, fill the resulting hole with several drops of 3% hydrogen peroxide. Reseal the flask and place it in indirect light for a few days. Hydrogen peroxide will break down to a harmless liquid very quickly in sunlight (after it has killed the fungus). Don't allow direct sunlight on the flask in case you cook the seedlings.

If the fungus is more widespread it is worth trying a reflask, i.e. transplant the protocorms (baby seedlings) to a new flask. As you take each plant out of the old flask give it a quick rinse/bath for a few seconds in 3% hydrogen peroxide. (Coelogynes are fairly tough but you may need to be careful with more delicate/sensitive orchids).

If I am deflasking plants into spaghnum moss for example, I never worry about any threats from mould. The moss will suit a healthy seedling better than it suits the mould and the seedling will soon outgrow the mould. I know a lot of people spray the seedlings with various chemicals and hormones when they remove them from the flask but I never bother. If your new plants are very valuable to you, however, you might want to ignore my experience and take out extra insurance by using some of the popular chemicals - even though Mother Nature doesn't bother with them!

Bottom Line:

Don't let any of the science get in the way. Keep it simple and have fun.

An excellent reference that is highly recommended if you want to get a bit more serious is:

Symbiotic Technique of Orchid Seed Germination by Aaron Hicks. Just Google his name.