Monthly Terrestrial Orchid Culture – August

With Spring on the way, things are starting to change in the Orchid House. Here are Les Nesbitt’ notes from the August Journal 2019 Vol 43 No 7

Terrestrial Culture – August

The days are getting longer now, noticeably so after the middle of the month. When the clouds clear, the sun is stronger & higher in the sky. Temperatures increase and growth speeds up. Lots of buds are developing so there is plenty to see in the orchid house. The greenhoods are a feature with Pterostylis curta, nutans, pedunculata and their hybrids are all flowering.

Pests become more active. Look out for aphids on flower stems. Depending on the season deflasking can start after the middle of the month if a sunny and dry Spring is forecast, otherwise wait until September.

The NOSSA Spring show is only a month away. Start preparing your specimen pots for the display. Any spare pots can be sold on the trading table. There are never enough terrestrials on the trading table at the show to meet the demand.

Photograph your orchids when the flowers are at peak condition. Then hand pollinate a flower or two to get seed for the NOSSA Propagation Workshop or for sowing around mother plants next autumn. Prepare two pots of each species, one for showing and one for seed.

 

How to hand pollinate.

Look closely at the flower column to see the positions of the pollen and the stigmatic surface. Flowers can be self-pollinated if there is only one. Fatter pods with more viable seeds result if two plants of the same species are cross pollinated. That is transfer the pollen from one flower to a flower on another plant. Cross pollination mixes the gene pool to prevent inbreeding. Use a toothpick or a she-oak needle to touch the pollen which will stick to the wood. Wipe the pollen across the stigmatic surface of the other flower and the job is done.

If pollination is successful, the flower will collapse in a few days and the ovary will start to swell. For greenhoods the stigmatic surface is halfway up the front of the column. Remove the front of the flower and the lip so you can see what you are doing. Greenhoods have yellow pollen. For Diuris and Thelymitra the white pollen is hidden behind the sticky stigma. Caladenia have yellow pollen under flaps at the top of the column. Stroke upwards to open the flaps as would an insect backing out of the flower. The stigma is a hollow sticky depression just below the pollen. You will have to tip the flower right back to see it.

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Monthly Terrestrial Orchid Culture – July

Continuing Les Nesbitt’s articles from the NOSSA Journal, this month’s (Vol 43 No 6 July 2019) is a relaxing time.

Midwinter is cold and cloudy most days. July is often the wettest month as well. A good time to sit by the heater and read orchid books or search the internet as you plan future activities. Tidy up your records and draw up a wanted list of terrestrials to purchase or swap. Activity in the lab continues with seed sowing and replating. Deflasking should wait until spring as tiny seedlings rot away if planted out in winter. Pots showing any signs of rot should be moved out of the
rain to dry off.

Not a lot to do in the orchid house except observe your orchids and watch for pests that are always looking for a feed. Growth will be slow. Give plants as much sunlight as possible. The very first seedling leaves may appear this month around mother plants. Give yourself a pat on the back if you see any seedlings. More may show in August & September.

Corybas flower this month and do not mind being cold and wet. Corybas flowers will shrivel up if the surrounding air is dry. Mist them daily or place a clear cover over the pot & the flowers will last for weeks. A tall plastic sleeve around the pot or an upturned glass bowl can be used.

Orchid clubs hold their Winter shows this month. Check them out for additions to your collection.

2017 August Cultural Notes

Steve Howard writes cultural notes for Adelaide conditions. These are his notes for August; for both epiphytes and terrestrials.

WATERING

Mounts daily.

Pots weekly. Small pots twice weekly depending on weather. Drier conditions for hot cold types. Terrestrial pots can dry out faster on warmer days so keep a watch on conditions.

FEEDING

Epiphytes: Recommending feeding towards months end as days lengthen. Many plants in strong spike growth and flowering now.

Terrestrials generally don’t need to be fed although weak organics like Seasol and Powerfeed applied in low doses can benefit colony type greenhoods.

PESTS AND DISEASES

Epiphytes: Botrytis will rot new buds in cold damp weather as fast as it attacks new growths from now. Aphids will increase sharply this month and favour new growth and spikes.  Pyrethrum sprays eco friendly and work well, so does a hose but dry spike straight after.

Some terrestrials will rot this month if conditions have been too wet or stagnant over winter. Note this for next season and add more drainage if this has been an issue.

 

GENERAL

Epiphytes: Keep flowering plants under cover  to enjoy. Soon will be the time to start thinking about re-potting and division as spring nears.

Keep flowering terrestrials out of strong winds and heavy rains as flower stems on some varieties are quite weak when grown in cultivation

Additional:

Later August will produce some warmer drying days as spring nears. Ensure small pots and plants don’t dry out at this time. Good time to check out seedling lists and prepare orders to ensure your plants arrive at the commencement of a new growing season.

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2017 February Winning Picture

1702 sm CC Cryptostylis subulata

The first competition for the year followed a wet orchid theme with three of the orchids being South Australian swamp orchids and the fourth from Western Australia; though not a swamp dweller, it grows in shallow moist soil.

The outstanding winner was Claire Chesson’s Cryptostylis subulata, followed by Robert Lawrence’s Spiranthes alticola, Rosalie Lawrence’s Pterostylis falcata and Pauline Meyer’s Thelymitra villosa.

Known to South Australian’s as the Moose Orchid, elsewhere it is either Large Tongue Orchid or Cow Orchid. This tall (40 to 110 cms) evergreen orchid is common in the eastern states where it is commonly found in damp areas as well as swamps. but in South Australia it is limited to swamps and is rated as endangered.

Leo Davis makes some interesting observations about the structure of this flower in his article Upside Upside Down which is well worth reading (https://nossa.org.au/2017/03/03/upside-upsisdedown/).

Whilst not an easy orchid to grow it has been cultivated although seed set has not always occurred. Helen Richards, an experienced Victorian terrestrial orchid grower, shared in an email how she grows them.

Cryptostylis species grow from brittle rhizomes which can be quite long and they resent frequent disturbance. Mine are potted into a pot therefore that is large enough for the long roots and which will accommodate further growth for several years. My mix is ANOS basic mix, the same as I use for Pterostylis and many other genera. They need to be kept moist all year round, especially in summer when they flower and new leaves appear, their active growing period. I grow them in an area of moderate light. Others have seen pollinators active on the flowers but I haven’t. However seed capsules frequently develop without my assistance with a toothpick. Richard Thomson says they haven’t had success germinating the seed.”

Reference

https://nossa.org.au/2017/03/03/upside-upsisdedown/

http://bie.ala.org.au/species/http://id.biodiversity.org.au/name/apni/89052

http://saseedbank.com.au/species_information.php?rid=1288

Personal communications Helen Richards (OAM), Chairman Australian Orchid Foundation

Bates, R. J., ed. (2011). South Australian Native Orchids. Electronic version, 2011. NOSSA

The other entries :

1702 sm RWL Spiranthes alticola

1702 sm RAL Pterostylis falcata

1702 sm PM Thelymitra villosa

Gleanings From The Journals: Who Was Our First Conservation Officer?

As the following article indicates there is much to be learnt from the old journals so much so that from time to time there will be a series of posts titled Gleanings from the Journals.

This first of the series was taken from Volume 36 No 10, November 2012 Journal of the Native Orchid of South Australia.

WHO WAS OUR FIRST CONSERVATION OFFICER?

Recently I’ve been looking over the old NOSSA Journals. I like (my husband says addictive!) reading history and even more reading original source material, so it’s not surprising that I’ve enjoyed this activity. There are some lovely gems in them. I like to read about the people, which brings me to the title of this article – Who was our first Conservation Officer?

Well if you ask Thelma Bridle, she’ll say that it was Karen Possingham but when I read in the April 1984 edition, I see that Margaret Fuller is said to be “the initiator of the Conservation Group” back in 1982. Margaret had a long involvement with the Bird Care and Conservation Group. She headed the NOSSA group who collaborated with the Education Department to produce Pic-a-Pac, an orchid teaching package for the schools.

Yet was Margaret the first? For I then read of two foundational members. Roy Hargreaves who is described as a “keen conservationist, ambassador and liaison person with numerous groups including SGAP, OCSA, Parks and Wildlife, the Adelaide Botanic Gardens, Black Hill Flora Research Centre, … an initiator of the R. S. Rogers Orchid House.” The other is Ron Robjohns who “drafted the Society’s Constitution and By-laws and formulated the Society’s Conservation Policy.” But ….. there is a third contender amongst the founding members – Peter Hornsby, the Society’s first editor and an organiser of field trips. Peter was always putting articles in the Journals relating to conservation. A keen conservationist and current member, he resigned his role as editor in 1981 to “concentrate on his study of the behaviour of the Yellow-footed Rock Wallaby in the North Flinders Ranges.” And yet we could continue for there were other foundational members who took a keen interest in conservation.

So who was our first Conservation Officer? Well, Thelma is right. It was Karen Possingham. She was the first one to have the title Conservation Officer when she was appointed to the role in March 1992 – fifteen years after the founding of the Society, and remained in that role until May 1997 when she became a councillor with the Burnside City Council. Karen formalised many activities, organizing bi-monthly meetings, Conservation Booths at the various NOSSA shows, lobbying, weeding, etc

Below is her report of their first meeting.

CONSERVATION GROUP PRIORITIES SET                                       K. Possingham

The first meeting of the 1992 NOSSA Orchid Conservation Sub-Committee was held on Wednesday 15th April. The following priorities were set at the meeting:

1) Lobby politicians; resolution to write letters to the Minister of the Environment, to National Parks and Wildlife, Department of Environmental Planning, Woods and Forests and Leaders of the Opposition Parties, and request a meeting in July to discuss Orchid Conservation strategy.

Liaise with other Conservation groups such as the Conservation Council; join at first as an Association Member and find out about South Australia’s conservation concerns and needs.

3) Monitor Hills Zone development; – liaise with Mt. Lofty Ranges Conservation Association.

4) Prioritise high risk sites that are not managed properly and in danger of clearance, habitat degradation etc.

5) In short term adopt a Reserve such as Belair National Park in order to monitor known Orchid populations, raise Society profile and provide assistance in weeding and other such requirements. This will provide conservation experience for members. There is easy access to Belair from Adelaide and the park and conservation activities should appeal to younger members as well as older members: we’ll be doing something concrete!

6) Possibility to apply for funding from Endangered Species Program, World Wildlife Fund and Save the Bush, to work on endangered orchids.

7) Education: area at Warrawong to be fenced off from animals for native orchids to be established and protected.

Meetings are to be held bi-monthly: Next meeting will be held on Wednesday, 10th June at 8

P.M. Anyone is welcome. Enquiries Karen Possingham, Conservation Officer, ph 364 0671.

Karen remained involved with the Conservation Group until the family moved to Queensland in 2000 where her husband Hugh took a chair in the departments of Mathematics and Biological Sciences at the University of Queensland. Prior to leaving Adelaide, Hugh had been President of the Nature Conservation Council, Professor of Environmental Science and Management at Adelaide University and instrumental in initiating biodiversity planning in South Australia. Hugh has made various trips back to Adelaide will be back here on 27th November to talk about Citizen Science prior to the Uni SA and ABC 891 Great Koala Count the next day.

I have wandered a bit from Karen as NOSSA’s first Conservation Officer but from what I can see in reading the Journals Hugh and Karen worked together in conservation and though no longer in South Australia are still actively involved in conservation. The objectives of that first meeting Karen left with NOSSA and continues to this day, albeit with changes to adapt to current issues and thinking.

Understanding the Conservation Status of South Australia Orchids

Endangered, Threatened or Rare?

Sometimes a particular species of orchid is said to be rare or endangered, for instance Thelymitra circumsepta* is listed as endangered in South Australia but has no listing federally whilst the endemic Prasophyllym murfetii* is listed as Critically Endangered federally but only Endangered in South Australia.

Prasophyllum murfettii (Denzel's Leek Orchid)

Prasophyllum murfettii (Denzel’s Leek Orchid)

What do these listings mean and why are they different for the same species?

What are the Conservation Categories?

Conservation listing by governments gives species a legal status, which can then be used to determine the type of consideration to be given to individual species in decision-making processes for species conservation.

In South Australia, the two main legislations affecting native orchids are the state National Parks and Wildlife Act 1972 (NPW) and the national Environmental Protection and Biodiversity Conservation Act 1999 (EPB). There is also the International Union for Conservation of Nature (IUCN) Red List which is used for international treaties. Each has their own set of categories resulting in terms with slightly different meanings.

The IUCN classification is quite detailed but in summary the conservation status used are

  • Extinct – not seen for fifty years or despite intensive searching not seen at a previously known site
  • Extinct in the Wild – no natural populations exist; only surviving in cultivation
  • Critically Endangered – known only from a single non-viable population
  • Endangered – in danger of extinction unless the factors causing decline are arrested
  • Vulnerable – likely to become endangered if the only large populations is wiped out for whatever reason
  • Near Threatened – close to qualifying or likely to qualify for a threatened category in the near future
  • Least Concern
  • Data Deficient
  • Not Evaluated

The Australian Federal government, under Section 179 of the EPBC Act, has six categories

  • Extinct – no reasonable doubt that the species has died out
  • Extinct in the Wild – no natural population existing, surviving in cultivation
  • Critically Endangered – faces an extremely high risk of extinction in the wild in the immediate future
  • Endangered – faces a very high risk of extinction in the wild in the near future
  • Vulnerable – faces a high risk of extinction in the wild in the medium term future
  • Conservation Dependent – if the cessation of a specific conservation program ceased the species could become vulnerable, endangered or critically endangered

South Australia uses three categories based on the categories from the IUCN Red List Categories and Criteria.

  • Endangered (Schedule 7) – includes Critically Endangered Extinct in the Wild and Extinct
  • Vulnerable (Schedule 8)
  • Rare (Schedule 9) – this is a South Australian term not recognised elsewhere but the criteria are consistent with the IUCN Near Threatened category and refers to uncommon species that are naturally limited in location or are in decline. Hence it is possible for a species to be common interstate but threatened in South Australia, for example Anzybas unguiculatus* is rated rare.
07 sm JP Anzybas unguiculatus 2

Anzybas unguiculatus (Little Pelican or Cherry Helmet Orchids)

Another term that is frequently used is Threatened. For the IUCN Threatened encompasses the three categories of Critically Endangered, Endangered and Vulnerable. It means that a species rated as threatened with extinction under these three categories may have different degrees of threat – note the adjectives in the IUCN definitions above. This serves as a guideline for its usage in South Australia. It should also be noted that Threatened and Rare are not interchangeable but a species rated Rare may be threatened by outside influences.

There is another level of conservation which is the regional status. This level does not have any legal standing but it is helpful in managing the species. The IUCN Red List Categories and Criteria are used to assign a regional conservation status. This is helpful in managing species at this level.

Why does a species have different Conservation Categories?

Looking through Part Two of South Australia’s Native Orchids 2011, it is not uncommon to find a species with two different conservation statuses. It is not surprising when they have the same status eg Arachnorchis behrii* is rated Endangered both state and nationally but why are the others different? Some of this is due to the different number of categories – six federally but only three at the state level so Diplodium bryophilum* is nationally Critically Endangered but only Endangered in South Australia as there is no critically Endangered category. Others have a state status but no national status, for example the endemic Diuris brevifolia* is rated Endangered. Curiously there are no endemic species with the combination of a national status but no state status, although there are five non-endemic species found in South Australia that do have this combination.

Diuris brevifolia (Late Donkey Orchid)

Diuris brevifolia (Late Donkey Orchid)

This comes about because there are two different bodies determining the statuses through two very different processes.

Nationally under the EPBC Act any individual can nominate a species which is assessed by the Threatened Species Scientific Committee, put out for public comment, changes adjusted as necessary and then the recommendations are passed onto the Minister who approves or rejects the nomination.

In South Australia, DEWNR (Department Environment Water and Natural Resources) initiates the process by asking the experts, compiling data, holding workshops with the experts. A report is written for the National Parks and Wildlife Council outlining the changes under the NPW Threatened Species Schedules. Once the changes are approved, it is sent to the Minister for approval before being released for public comment. After any necessary adjustments the report is then sent to the South Australian Parliamentary Cabinet for final approval.

Both processes check the species under consideration against the IUCN criteria.

How many South Australian orchids are under threat?

On 22nd July 2014, Doug Bickerton presented a talk at the Native Orchid Society on the conservation status of South Australian orchids. The comparison between the State and Federal listings was as follows:

Number of Orchids with a Conservation Status under the NPW Act (State)

  • 77 species Endangered
  • 33 species Vulnerable
  • 32 species Rare

A total of 142 species or 49% of all South Australian orchids are recognised to be under threat.

Number of Orchids with a Conservation Status under the EPBC Act (Federal)

  • 4 Critically Endangered
  • 22 Endangered
  • 19 Vulnerable

A total of 45 species for the State have a Federal government legal conservation status.

The fact that one authority recognises a species and the other authority does not doesn’t mitigate against the seriousness of the threat to that species. The fact that a species does not have a conservation status from either authority does not mean that it is not under threat. It could still be in danger of extinction.

Cryptostylis subulata (Moose Orchid)

Cryptostylis subulata (Moose Orchid) State Conservation Status: Vulnerable National Conservation Status: not listed

Currently in South Australian there is a State-wide assessment underway and the results will be published in 2016.

This article was inspired and is based upon notes taken from a talk given by Doug Bickerton in 2014 at the Native Orchid Society of South Australia. I would like to thank Thelma Bridle, Conservation Officer, Native Orchid Society of South Australia, for her help.

*Based on information found in South Australia’s Native Orchids 2011

References:

South Australia’s Native Orchids Bates 2011

http://www.environment.gov.au/biodiversity/threatened/species#categories accessed 13th November 2015

http://www.environment.sa.gov.au/managing-natural-resources/Plants_Animals/Threatened_species_ecological_communities/Conservation_status_of_threatened_species/State accessed 13th November 2015

IUCN RED LIST CATEGORIES AND CRITERIA Version 3.1 Second edition Prepared by the IUCN Species Survival Commission As approved by the 51st meeting of the IUCN Council Gland, Switzerland 9 February 2000

 

How Much Fertilizer Do I Need For My Australian Terrestrial Orchids?

The short answer is very little to none at all. As long as there is some organic matter in the soil mix terrestrial orchids will grow and flower without added fertiliser.

For fungus dependent orchids, such as Caladenia, a fresh layer of leaf litter added in summer to the top of the pot is all that is required. These orchids are seldom repotted.

Growers who show their non fungus dependent orchid plants for judging want strong superior plants.  They add a pinch of blood & bone fertilizer to each pot during the annual summer repotting. Vigorous orchids like the colony forming greenhoods will respond to weak foliar feeding in the early growth stages, (April to July).  If fertilizing is overdone the plants can burn or produce multiple flowers that grow into one another and ruin the spectacle of flowers.

Other factors are more important than fertilizer.  Strong light in winter, constantly moist potting mix, excellent drainage,  good air movement and a pest free environment are more important.

Thelymitra plants in pots

Thelymitra (Sun Orchids) in cultivation

Pot of Caladenia latifolia cultivated by Les Nesbitt

Caladenia latifolia in cultivation

Diplodium robustum - one of the cauline greenhoods

Diplodium robustum – one of the cauline greenhoods

When do I stop watering my Greenhoods?

This was the question posed to Les Nesbitt at the September monthly meeting.  Later there was some further discussion, of which see below:

When do I stop watering my Greenhoods?

The short answer is when the leaves go yellow and start to die off, usually in October- November. Allow the pot to dry out completely to dry up the roots and old tubers so that they do not go mouldy and rot the new tubers.

Australian terrestrial orchids form tubers underground. The mature plant dies back at the end of the growing season and enters a period of dormancy which for South Australian terrestrials is over summer.

A general principle of watering is to match the watering to the rainfall pattern. Whilst there is minimal rain over summer, when dormant tubers are in pots it is important to not let them stay dry for months and become desiccated. A light sprinkling every week or two is sufficient.

Unicode

Pterostylis ‘Nodding Grace’ This is an hybrid between P. nutans and P. curta. Obviously it is not time to stop watering.

When do I start watering again? 

For the cauline group (Diplodiums) from South-eastern Australia start watering at the end of January as the tubers are starting to shoot by then. For other greenhoods start light watering in late February and gradually increase the water until shoots appear usually in March-April. Do not let the pots dry out once leaves are visible.

Diplodium robustum - one of the cauline greenhoods

Diplodium robustum – one of the cauline greenhoods. Note difference the between the leaves of the non-flowering rosettes and the flowering plants.

Other cultivated Australian terrestrial orchids require a similar watering regime although leaves of some appear later in May or June.

2015 July Winning Photograph

07 sm JP Anzybas unguiculatus 2

Anzybas unguiculatas (common name Little Pelican or Cherry Helmet Orchid) was the main focus for this month’s competition with three photographs of this diminutive flower.

The other photographs were Ed Lowrey’s close-up of a triggered Urochilus sanguineus labellum, John Badger’s first Diuris palustris sighting for this year and Pauline Meyer’s mass flowering of Leptoceras menziesii post fire. Of the Anzybas, Jenny Pauley entered two and Lorraine Badger one. Jenny Pauley’s photograph of two flowers was the outstanding winner.

Originally named Corysanthes unguiculata (1810), then Corybas unguiculatus (1871), the genus name was changed in 2002 to Anzybas in recognition of its distribution both in Australia in New Zealand. Since 1945 it had been recognised that the New Zealand species Corybas cheesemanii was a synonym for Corybas unguiculatas although the juvenile plant can have two leaves unlike the Australian species which is single leafed.

An interesting feature of this flower is the prominent white ears at the rear of the helmet (not clearly seen in this photograph) which are part of the labellum.

These plants are small. The gum leaves and twigs give an idea of size but the engagement ring shows it very clearly.

These plants are small. The gum leaves and twigs give an idea of size but the engagement ring shows it very clearly.  Note also the prominent ‘white ears’ of the labellum.

An unusual aspect of this photograph is that the colour of the underside of one of the leaves. It lacks the characteristic distinguishing feature of the purple underside of the leaves. According to orchid growers, the light affects the leaf colour. Heavy shade produces green leaves. It is possible that the heavy leaf litter where this plant was growing provided enough deep shade to cause the colour loss.

Bates (1990) states that it (has) not proved amenable to cultivation, but it has, on rare occasions, been benched at NOSSA meetings with the most recent occurrence was in July 2010 but it remains a very difficult plant to cultivate. The electronic version Vol 34 No 7 has a photograph of the plant just visible within the moss.

It is not always easy to photograph this species as not only is it rare with limited numbers but there are very few sites where it can be found. Added to that is that the window of opportunity is short in South Australia with a flowering time from June to August compared with those interstate which can range from May to October.

There has always been an interest in Australian orchids.  Over the years there have been many photographs of orchids.  This stereographic postcard from 1928 is a study in beauty – https://i1.wp.com/www.slv.vic.gov.au/pcards/0/0/4/im/pc004332.jpg

This postcard is held by the State Library of Victoria.

Although the distribution covers the Southern Lofty, Kangaroo Island and the South East regions of South Australia, it has become increasingly rare due to loss of habitat which consists of leaf litter on damp soils.  As a result, there are very limited localities where they can now be found.

It is one of our earliest helmets to flower which is from June to July.

References

http://www.flora.sa.gov.au/cgi-bin/speciesfacts_display.cgi?form=speciesfacts&family=&genus=corybas&species=unguiculatus&iname=&submit=Display accessed August 5 2015

Les Nesbitt personal communication

Jones, David L (2006) Native Orchids of Australasia, Frenchs Forest, NSW: Reed New Holland.

Bates, R.J. & and Weber, J.Z. (1990). Orchids of South Australia, Adelaide: Flora and Fauna of S.A. Handbooks Committee

https://biodiversity.org.au/nsl/services/instance/apni/499184 accessed August 5 2015

https://www.anbg.gov.au/cpbr/cd-keys/orchidkey/html/genera/Anzybas.htm accessed August 5 2015

Bates R, (Editor) 2011 South Australia’s Native Orchids (CD-ROM), Adelaide: NOSSA

Journal of the Native Orchid Society of South Australia Vol 34 No 7 August 2010

http://rsnz.natlib.govt.nz/volume/rsnz_76/rsnz_76_04_007280.html accessed August 5 2015

Rupp, HMR and Hatch, ED (1945) Relation of the Orchid Flora of Australia to that of New Zealand in Proceeding of the Linnean Society of New South Wales Vol 70 1945, pages 53 – 61

https://archive.org/stream/proceedingsoflin70linn#page/60/mode/2up accessed August 5 2015

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.