A Timely Reminder

This article is reprinted from  Volume 39 No 11 December 2015 Native Orchid Society of South Australia Inc. Journal

Tuber Repotting Time is here

Les Nesbitt

Now that Australian terrestrial orchids have gone into dormancy it is time to think about repotting and preparing for the next growing season.

The best months for this activity are December and January.

I will limit this discussion to the easily grown colony forming terrestrial orchids as these are more likely to be available – for easily grown terrestrials, click here.


We need more terrestrial growers in NOSSA to feed the tuber bank and to supply spare pots for sale to the public at the Spring Show. I found it embarrassing to see so few terrestrials for sale at the 2015 Spring Show compared to the numbers available in years gone by.

Growing terrestrials is a rewarding hobby that does not take up much time or space and will pay for itself. Plus you are doing something effective orchids and the environment even if only the most common terrestrials are grown (eg the greenhoods and onion orchids). Consider easily grown, fast multiplying, Pterostylis curta (listed as rare in the SA Act) has been widely grown in NOSSA collections since the days Roy Hargreave’s wash trough when NOSSA was formed.

Once the basic principles are understood it to move onto the rarer species as artificially propagated plants become available in future as they surely will. Members can draw on the tuber bank in December to get started seriously about it as a group of volunteers will be needed within a year or two to help look after the output of a number of projects already underway or about to start.

Year 8 girls at Kildare College have been repotting the school’s terrestrial collection and this is how they did it.


Prepare all the materials needed including:

  • Pots
  • crocking material,
  • sand
  • organic matter
    • blood & bone, native compost, chopped up sheoak needles
  • 4B pencil and labels.


  • Water the pots lightly a day or two before repotting. The mix should be damp enough to not be dusty, yet dry enough to not stick to everything.
  • Remove the label, wash it in a container of water and stand it aside to dry.
  • Check on the label back to see how many tubers were planted last year.


Scrape off and dump the top layer of soil as this can be contaminated with moss, slimy bacteria and liverworts.

  • Tap out the plug of soil into a sieve sitting on a bowl. Pick out any tubers that are visible on the outside of the plug.
  • Gently break the soil apart and search for tubers while squashing the lumps of mix through the sieve.
    • Very small tubers may go through especially with Corybas. If you have not got a sieve do this operation on a sheet of newspaper.

Place the tubers in a dish so they do not roll away.

  • Count the new tubers to see whether they increased by 2, 3 or 4 times.
  • Discard anything left in the sieve (old tubers, roots etc.).
  • Work out how many new pots are needed to plant all the new tubers.

Add to the old mix in the bowl

  • a pinch of blood & bone,
  • a handful of sand and a handful of native potting mix.
    • Also add enough of these ingredients for each additional pot and mix the contents of the bowl together.

Select new or sterilised 125 mm standard pots

  • and place a square of shadecloth in the bottom to keep the sand in and critters out.
  • Pour in mix to within 30 mm of the top and ram down with your fist.
  • Place up to 10 tubers on top of the mix.
    • Lay tubers horizontally if unsure which is the top.

Labelling and finishing the task

  • Write out the orchid name on extra labels and fill in the numbers of tubers on the back for each pot.
  • Almost fill the pot with mix and tamp down.
  • Insert the label. Place a layer of cut sheoak needles on top of the mix.
  • Water the pots and the job is done.

For show pots use 175 mm or larger pots and plant 20 to 50 of the largest tubers available.

If the tubers have decreased or look unhealthy, throw out all the old mix and replant in new mix.

Repotting a Diuris

Related Articles:

Growing Terrestrial Orchids Part One of Four

Growing Terrestrial Orchids Part Two of Four

Growing Terrestrial Orchids Part Three of Four


2015 October Winning Photo

Diuris brevifolia (Late Donkey Orchid)
Diuris brevifolia  (Late Donkey Orchid)

Again this month was a varied selection of species with Pauline Myers’ Caladenia chapmanii (WA), Claire Chesson’s Thelymitra rubra, Jenny Pauley’s hybrid of Arachnorchis brumalis x conferta, David Hirst’s Caladenia discoidea and the winning entry, Rosalie Lawrence’s Diuris brevifolia.

This strikingly yellow flowered donkey orchid endemic to South Australia is listed as Endangered. Its range was once quite widespread in the southern Adelaide Mt Lofty Range region but now it is now restricted to pockets on the Fleurieu Peninsula and western Kangaroo Island in Heathy Woodland, Wetland and Riparian habitats.

There is interest today in cultivating orchids for conservation or ex situ conservation. With the reduced range of this species, can it be cultivated and thus continue to ensure its survival as a species? Some sources seem to suggest that it is an easy plant to cultivate, and some Diuris are easier than others, but Les Nesbitt points out that he has some plants from a rescue dig several years ago and that they have not multiplied very much in that time. This suggests that they may be dependent on a specific fungi. Though it has not been hugely successful in cultivation, it is worth noting that it has been used to produce hybrids with several other Diuris.


Bates, R. J. (2011) South Australia’s Native Orchids NOSSA DVD, Adelaide

Nesbitt, L personal communications

Adelaide and Mount Lofty Ranges South Australia Threatened Species Profile Fact Sheet – Diuris brevifolia

Why use a mulch on your potted terrestrial orchids?

Here in South Australia, it is very common to see a covering of She Oak needles (Allocasuarina sp.) on pots of terrestrial orchids.  According to Les Nesbitt, NOSSA founding member and experienced terrestrial orchid grower, there are four reasons for this

  • It keeps the leaves up off the soil.
    • Provides good air circulation
    • Helps prevent leaf rot.
  • It provides nutrients to the fungi
    • This is very important for the fungi dependent orchids.
  • It stops pitting into the soil when it rains.
    • This is most likely to occur when pots are under the drip line of a shade-cloth.
    • Pitting exposes the root system.
  • It allows the leaves to readily come through because of its small diameters.
    • Other mulches, such as gum leaves, smother seedlings.

She Oak needles are the choice of mulch because it is

  • Long lasting and takes more than year to break down
    • which means that it lasts the whole growing season.
  • Does not become mushy or spongy
    • unlike pine needles and grass cuttings which breakdown more quickly into a wet soggy mass and contribute to leaf rot.

It should be noted that it is necessary to replace this mulch yearly.

These two pots were in the same area under the shadecloth.  Notice the damage to the pot without the mulch.
These two pots were in the same area under the shadecloth. Notice the rain damage to the pot without the mulch.

Advice from the past – Start Watering

In 1984, G.J.Nieuwenhoven was the editor of the NOSSA Journal.  In February of that year he wrote the following:

Welcome back to NOSSA.

 After the holiday break we are all looking forward to the next meeting to talk about our favourite plants and renew friendships.

Several members have reported an early start to the terrestrial season with Pterostylis species, a couple of Diuris species popping up already.  For some of the eastern states Pterostylis of the cauline group this is normal, especially if you keep the pots cool during the summer (a cellar is ideal but underneath a shaded bench in the shadehouse will do nicely). Very light watering should take place when the first shoots appear but do not overdo the watering or place pots in the sun for we are sure to get some more hot weather yet and this could cook your plants before you know it.

The Diuris are really out of season but it was probably the rain in late December and early January that started them off, anyway, these too should be kept slightly damp if they are up.

If you have not finished repotting by now it would be best to leave it until next year as the new shoots which are already beginning to grow from the tubers are very easily broken off while sifting them from the soil.

Apart from that all you can do is wait for the rains to come in March and then start searching for plants to appear – and keep those fingers out of the pots or you may damage one of your best plants looking for the new growths.

This is also the time to start taking notes when plants first appear, etc.:

  • when they flower and how many flowers from a given number of tubers;
  • what kind of soil; what conditions (i.e. shaded or not, damp or dry).
  • Anything that may assist in years to come to help you understand and grow our orchids better and, more importantly, multiply them.
  • A card index system would be a good way to store information, otherwise an exercise book will do.


The timing of the article tallies with the advice that was recently given at the end of February – start watering the terrestrials now if you haven’t already begun.  Hopefully by the flowering time you will have a lovely display of terrestrials such as the Thelymitra, Arachnorchis and Caladenia featured below.


Pot of Thelymitra Kay Nesbitt Cultivar copyPot of Arachnorchis argocallaPot of Caladenia latifolia cultivated by Les Nesbitt

ABC Gardening – Terrestrial Orchids

Back in 2013, Gardening Australia of the ABC produced a video featuring Helen Richards, a Victorian who has in-depth knowledge of growing terrestrial orchids.  Though Helen lives interstate and adaptions do need to be made for different locations and conditions, this video of her shadehouse is very instructive for any South Australian’s wanting to grow their own terrestrials.

Click here to view the video and read the text.

Pot of Thelymitra Kay Nesbitt Cultivar copy
Pot of Thelymitra ‘Kay Nesbitt’ cultivar
Pot of Arachnorchis argocalla
Pot of Arachnorchis argocalla
Pot of Caladenia latifolia cultivated by Les Nesbitt
Pot of Caladenia latifolia

October 2014 Winning Photograph

 Caladenia procera

This month’s entries of Oligochaetochilus arenicola, Caladenia flava, Calochilus robertsonii , Diuris palustris and Caladenia procera illustrated the variety of shapes to be found in orchids.

All but one are reasonably common; all but one were photographed in situ and that one was the winning picture by Kris Kopicki – Caladenia procera. Its common name, Carbunup King Spider Orchid, reflects its location near Busselton Western Australia. This species has a severely limited distribution with a small population and is threatened by land clearing for development. Consequently it is rated as critically endangered.

The other aspect of this plant is that it is a photograph of a plant in a pot not the bush. Kris benched the original plant at the September Tuesday meeting when it was still in bud. By Saturday it was in glorious flower.

This picture exemplifies the two objects of NOSSA which “are to promote and engage in activities for the promotion and furtherance of:

  1. the culture, propagation, conservation, knowledge and scientific study of the native orchids of Southern Australia and the Australasian region;
  2. the preservation of orchids as a species and their preservation within their native habitat.”

Some terrestrial orchids are relatively easy to grow but not this one. It takes time patience and skill to grow them. C procera is one of the fungi dependent species and though capable of living many years, it can take up to six years before flowering, although under ideal condition it could mature in as little as two years.

Being able to grow the different terrestrial orchids is one of the ways NOSSA can help in their conservation. NOSSA has a Growers’ Forum each meeting night where members can attend and learn from experienced growers how to grow both epiphytes and, importantly, the terrestrials.


Native Orchid Society of South Australia Inc. (NOSSA) Rules of Association 2007

Caladenia procera – Carbunup King Spider, Orchid Species Profile and Threats Database (SPRAT) – http://www.environment.gov.au/cgi-bin/sprat/public/publicspecies.pl?taxon_id=68679 – access 6th November 2014

Remember November’s theme is Orchids and Insects (Spiders and other critters accepted as Honorary Insects)

Bananas Trigger Flowering of Orchids


Some native terrestrial orchids only flower in the season after a bushfire.  They are stimulated by the hot gases given off during the fire.  One of those gases is ethylene.  Bananas are shipped down from Queensland to the southern states of Australia as green bananas to stop fruit fly outbreaks.  On arrival they are put in sealed rooms and exposed to ethylene gas.  The bananas ripen a few days later.  Traces of ethylene remain in the banana skin.  Overripe fruit also emits ethylene gas.  Orchid flowers do not last long if ethylene is present in a closed glasshouse.

We know that dormant tubers exposed to ethylene often flower the next season.  The best example is the Hare orchid Leptoceras menziesii.  In summer I put dormant tubers in a small dish in a plastic bag with a banana skin and seal the bag with a rubber band.  The skin may go mouldy so should not touch the tubers.  I leave the bag inside my shed for about 2 weeks then remove the tubers and pot them up.  The exposed plants make leaves almost twice as large as normal tuber leaves.  This procedure should not be carried out with the same plants the following year as they may get exhausted and die out.  I have found results with other shy flowering species are not so reliable.  Maybe they need a stronger does of ethylene.

Article by Les Nesbit

Banana & Banana PeelVol 38 No 5 June 2014

NOSSA Journal

A Revolution of a Sweet Kind

Ever since the Western world discovered the orchid in the 18th and 19th century there have been enthusiasts wanting to grow them but though an orchid may produce millions of seeds, for they are minuscule, only a relatively small number germinate.  The seeds do not have any stored food and are dependent upon fungi for germination.  This made it difficult for early orchid growers who relied on obtaining specimens from the wild – a most unsustainable practice!

Yet today cultivation of orchids is flourishing.  It is not dependent upon removing specimens from the bush.  In Australia it is illegal.

Today the orchid enthusiast can grow orchids from seeds at home.  The technique, invitro embryo germination, is popularly known as flasking.  It involves growing the seeds in a sterile agar medium to which the most significant ingredient was the addition of sugar.

At the time it was developed by Professor Lewis Knudson (1884 – 1958) of Cornell University in 1922 this method was revolutionary.



Rasmussen J, April – June 1986, “Contact Dermatitis from Orchids” Clinics in Dermatology Volume 4 Number 2

Below are some examples of terrestrial orchids grown from seeds in flasks.

Flasking Terrestrial Orchid Seeds (3)  Flasking Terrestrial Orchid Seeds (2)  Flasking Terrestrial Orchid Seeds (1)

Photographs kindly supplied by Les Nesbitt.


South Australian Terrestrial Orchid Culture Notes Part Four of Four Parts

Re-establishing Orchids

Replanting in bushland should be restricted to orchid species that grow or once grew in the local area. No hybrids please.

If planting out in the garden or bush, choose a location with good air movement and winter sun and a thin layer of surface mulch. Slashed native ground cover is good. Native terrestrial orchids cannot stand competition from weeds, grasses, slugs and snails and scratching blackbirds (all introduced pests). They will rot away in dense weeds or dense understory plants. If in a frost prone area they may need overhead protection from a shrub or trees. For plants in growth, dig out a hole a little bigger than the tube. Knock out the tube and insert the contents into the hole and backfill with as little disturbance as possible. Dormant tubers can be planted in a furrow, 50mm or more deep, and backfilled just like planting beans. Water in. The colony forming species will spread out and form patches of plants over a period of several years.

Orchid seed is like fine dust and can be mixed with fine dry sand to help spread it over a large area. Broadcast using a pepper-shaker over a suitable site. Results are dependent on the season and whether fungi are present. This method is slow to show results as flowers may not be seen for 5 to 10 years after seed is sown. More seedlings germinate if there are mother plants already growing.

Pot of Arachnorchis argocalla

A pot of Arachnorchis argocalla, 40 cm tall (Fungi Dependent)

To learn more about re-establishing orchids in the bush, visit the Vale Park Our Patch website to see the work being done by Heather Whiting and her team.

South Australian Terrestrial Orchid Culture Notes Part Three of Four Parts

Maintenance throughout the year


  • During summer, very lightly water surface of pots weekly to prevent tuber desiccation especially if dormant seedlings are in the pot.
  • Divide overcrowded pots in summer. Tip out and break into slices like cutting a cake. Stand a slice in a new pot & fill spaces with fresh mix. Take care to keep the surface layer at the surface of the new pot.
  • Add fresh leaf litter to surface layer in January to February to March.
  • If surface moss gets too thick, peel it off and discard in summer.


  • Start heavier watering of pots weekly from mid March.
  • Mix seed with fine dry sand and sprinkle on mother pots in April.
  • Water as required in autumn, winter & spring so that pots never dry out during the growing season yet are not soggy wet.
  • Leaves appear from Anzac Day to June.


  • Look for flower buds down inside the largest leaves from mid July onwards.
  • Look for new seedling leaves from August to October.


  • Enjoy and photograph flowers September to November.
  • Hand-pollinate flowers in September – October. Flowers collapse within days of fertilisation.
  • Collect seed pods as they turn brown just before they split open in November – December.
  • Dry & store seed over summer in paper envelopes kept indoors.
  • Allow pots to slowly dry out in mid – late November to induce dormancy and ripen tubers. Plants die down completely in summer to underground tubers.

For further information on growing fungus – dependent orchids refer to:

  • Orchids Australia’ February 2006, P58, or ‘The Orchadian’ Vol 15, Number 3, March 2006, P100.

Pot of Caladenia latifolia cultivated by Les Nesbitt

Caladenia latifolia cultivated by LN (Fast Multipler)

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