by Lynda Coles … June 2022
These articles are split into several sections which will appear over the next few weeks and are primarily aimed at those wishing to begin sowing orchid seeds in sterile conditions, and raising them through to deflask, although I am sure, that those who already have some skill at this task may find something of interest, even those who, like me, have been undertaking this activity for many years may also discover something helpful .. I know that I can still find new information about it.
I have grown Orchids for more years than I can remember, for most of that time, apart from growing the adult plants, I have also grown them from seed, small numbers at first but since beginning flasking I have sown and successfully de-flasked hundreds of orchids, with almost all of them being species, the remainder being primary crosses or remakes of natural hybrids. From that time until just a few years ago, I generally kept just a small quantity of seedlings to final re-flask, not having a great deal of room for them once removed from the jars, of course, this meant a lot of plant material was discarded before ever getting to the final flask, which clearly was a waste, both of plant material and effort.
Conservation remains a concern, perhaps more so now than ever before, so now I not only grown more species but also retain far more seedlings both in flask and out, I accept that my plants will never be used to re-introduce in the wild but those I raise may, at least, be kept in circulation.
Currently, I have a great number of orchid species in the in-vitro cultivation cycle either just sown, in one of the several stages of flask, or as acclimatised seedlings ex-flask. I hope to continue expanding the numbers of individual species and the numbers of them brought to final flask, which should include some of the terrestrial species native to the UK.
Lists of the flasks and seedlings that I now have available can be requested from my entry on the Links page.
About orchid seed.
The ripe seeds of an orchid are extremely small and dustlike. They have very little or no food reserves in the form of endosperm or large embryo, most are unable to germinate and grow without a mycorrhizal fungi partner. Each seedpod contains many hundreds, thousands or even millions of individual seeds which are dispersed by the wind and if any are to grow then they must land where a particular type of fungi is found. Seeds can be carried many miles from the parent plant but only a very few will germinate and grow to be adult plants themselves.
It is quite possible to grow orchid seeds by sowing them onto a sterile, nutrient-rich gel that contains all of the food needed to germinate and grow until sufficiently developed to a size where each can survive outside of the growing vessel. Laboratory conditions are not required and using simple and readily available equipment you can successfully sow orchid seeds at home.
The basic equipment that you will require to sow ripe, dry orchid seed is ..
- A working area.
- A heated pressure vessel.
- Suitable gel media to sow your seeds onto.
- A chemical sterilant for your workspace.
- Containers to process the media and germinate the seed.
- A chemical sterilant for the seeds.
- Suitable tools to handle the seeds.
- Good quality water.
- A few small containers to use for wash water.
- If you can find some, then autoclave indicator tape.
- A small number of viable Orchid seeds.
The workspace.There are many ways to create a sterile workspace, some are more successful than others. A laminar flow cabinet must be at the top of the list but they are expensive, although it is possible to make your own it is still going to be expensive. The simplest and most cost-effective is a suitably sized plastic storage box or similar, fashioned into a glovebox. These do not have to be large but should have enough room inside to hold the containers of media together with a small jar of sterile water to rinse the seed and a small spray bottle. The container must be large enough for you to manipulate the items within. A search on your internet browser will find many designs.
The pressure vessel. Household pressure cookers are very suitable providing that they are able to hold a 15psi pressure .. not all can so choose carefully.
Suitable gel media. A product sold as P668, (Merck) Orchimax (Duchefa, available in the UK from Melford), Knudsons, and others will be suitable for most tropical orchids and some terrestrials (even some UK natives). Whichever you decide to use, be consistent, I would strongly advise against weighing out portions from a larger volume of dry media … some of the chemicals in the formulae are included in very small quantities and you will never be sure that all components are present in their correct proportions.
Chemical sterilant for your workspace. The most widely used ones are household bleach, peroxide or an alcohol solution (IPA), some use UV lights. Be very careful when using any of them.
Containers for your media. Plastic tubs are often used. Polypropylene should be acceptable, alternatively, glass jars or laboratory flasks are available in many sizes and shapes, just ensure that your choice has a tight-fitting lid or that you have a suitable rubber bung for it and that it will fit into your pressure cooker. All of these materials can be reused or recycled and will withstand the conditions inside a pressure cooker.
Chemical sterilant for the seeds. The most commonly used chemical for this purpose is a 3% peroxide solution or a weak (10%) solution of household bleach … the thin unscented sort, buy a fresh bottle …. or calcium hypochlorite. There are others but those mentioned are readily available.
Suitable tools to handle the seeds. A few small volume tubes with lids, small test tubes or a small syringe.
Good quality water. Use RO water, readily available and sold for use as battery top-up or for irons, or distilled water. Do not use tap water, rainwater, well water or any other type … those are not pure enough.
A few small containers for wash water. Virtually any small volume container will do.
Autoclave indicator tape. This tape will show you that the contents of the pressure vessel have been exposed to the sterilisation process. Its use is not essential and can be omitted if you wish.
A small number of viable orchid seeds. Of course, in normal conditions, you will not be able to count the seeds, they are far too small, as a guide use a quantity smaller than a grain of rice. Fresh seed with embyros should be viable but older seed that has not been dried may not be viable or only minimally so, properly dried seed should keep well for some years. There are a few orchid species that must be sown fresh because they do not remain viable for long and a procedure to achieve that is not yet known.
PPE. Take steps to protect yourself from the chemicals that you will be using, gloves, goggles/safety glasses ….. the chemicals are capable of giving a painful burn and can damage your eyes if splashed into them.
This article will be continued to completion … please revisit frequently.
If you are interested in the purchase of my flasks and seedlings please request a current list …follow my link on our links page.