Creating a Mosquito-free Micro Climate for Epiphytes

Adelaide in summer is very dry and hot with very little humidity or rain.  Since January 2015 there has been over 60 days without any significant rainfall.  This presents a problem for growing Australian epiphytes which come mainly from the eastern seaboard with its increased humidity and summer rain.  Therefore to grow ephiphytes in Adelaide, it becomes necessary to attempt to replicate these conditions through creating a micro climate with increased humidity.  To achieve this many growers will stand the pots on gravel in water-filled trays but this presents a problem.  Mosquitoes love it and rapidly breed up to the annoyance of us all.

The following system stops mosquitoes from breeding plus prevents pots getting water logged in Adelaide’s winter, particularly when the pots are not under a solid roof but shadecloth (in this instance, 50% shadecloth).

  • Equipment
    • 10 Black trays – these were inexpensive trays from Cheap as Chips
    • Black irrigation tubing
    • 10 Grommets
    • 11 ‘T’ junctions and 2 angle junctions
    • Tap
    • Sealant
    • Gravel
    • Builders Landscape Fabric
  • Preparing the trays
    • One hole was drilled in each of the trays.  A grommet was placed in each hole and using ‘T’ and corner junctions the trays were joined with poly tubing including a tap.

      The trays connected.  To give stability the trays and hose were connected to the table top.
      The trays connected. To give stability the trays and hose were connected to the table top with the hose running under the table top. This allows free drainage as it stops the hose from being squashed.
  • Checking the system for leaks
    • The next step was to check that the water flowed into all the trays and that there were no leaks.

      Filling all the trays from one tray.
      Filling all the trays from one tray.
    • There were leaks and these were sealed with an aquarium sealant.
    • A hose with a tap was directed toward a raised garden bed on the other side of the shadecloth.

      Checking for leaks & the drainage system
      Tubing leading to the raised garden bed
  • Preparing the inner tray
    • The system requires a second tray.  Drainage holes were drilled in the trays.

      Inner (upper) trays with holes to allow the water to come up into the pots.
      Inner trays with holes to allow the water to come up into the pots.
    • Gravel was placed in the outer (lower) tray.

      Gravel to support the inner trays
      Gravel to support the inner trays
    • The reason was two-fold.  One was to make it easier to remove the inner tray with the pots insitu and the other was to hold the builder’s landscape fabric nearer the inner tray.  The purpose of the fabric is to keep the tubing clear of debris.

      Layer of cloth to stop debris entering the drainage pipes
      Layer of cloth to stop debris entering the drainage pipes
  • The finished system
    • Pots in place and ready to enjoy the new growth of those numerous plants that were divided previously – see the post Breaking up is ….. easy to do.

      The front pot originally consisted of just the pseudobulbs without leaves of Dendrobium kingianum.  After a few weeks in this system, new growth.
      The front pot originally consisted of just the pseudobulbs of Dendrobium kingianum. There were no leaves. After a few weeks in this system, new growth has appeared.
  • Using the system
    • Depending upon the conditions, the mosquito breeding cycle can be as short as four days from egg-laying to the larva emerging as a adult.  As a result, the water is fully drained every four days or less.  This regular drainage of water means that there is no stagnant water left lying around for any prolonged length of time.
    • The trays are allowed dry for a couple of days (less in a heat wave) before refilling again and the pots sit in a small amount of water.
    • By following this watering cycle there are no mosquitoes.
    • The shallow layer of water around the pots provides the necessary humidity.
    • In winter the taps are left open the whole time to prevent the plants from becoming water-logged.

NB This system is not suitable for the terrestrial orchids.







Australian Orchids & the Doctors They Commemorate Part 16 of 20

Hereward Leighton Kesteven (1881 – 1964)

A general medical practitioner, medical scientist, zoologist, pioneer of industrial medicine in Australia, and national medical director of the Allied Works Council during World War II.


Dendrobium kestevenii  is the name applied to the hybrid between D. speciosum subsp. speciosum and D. kingianum

Breaking up is …. easy to do

Attempting to divide a large Dendrobium taberi  (Dendrobium speciosum var. hillii or Thelychiton tarberi) for the first time can be daunting but with a little instruction and guidance it is not quite as hard as it seems. If left, these plants just get bigger and bigger ……

Den tarberii pre-repotting (4)

… and if you would like to see a magnificent one that’s in flower, click here.

Here is my first time attempt at dividing a Dendrobium tarberi.

  1.  First the pot was allowed to dry out a bit – no watering in the days before.
    • A drier plant is easier to divide.
  2. All the necessary equipment was assembled before starting
    Equipment (3)
    Assembled equipment including Snail repellent, Bleach for cleaning pots & equipment, wettable sulphur for putting on the fresh cuts
    • All equipment to be used was disinfected.
    • For though tough, the plants will be placed under stress making them vulnerable to the risk of infection.
  3. The pots were washed in bleach as per instructions on the container, including the wearing of gloves.
  4. The plant was removed from the pot by
    • by giving the pot some good knocks with a mallet. This loosened the plant and made it easier to remove without damaging the pot
    • and then it was given a good shake to remove the loose potting mix
  5. Next the plant was examined for areas of natural cleavage which were then pulled apart.
    • This is the place to start dividing the plant.
  6. The plant was still quite big so then tried using a mallet to try and loosen the plant and find more natural cleavages but wasn’t successful
  7. The whole plant was picked up and dropped from chest height several times
    • This finally caused the plant to split
  8. As the plant started separating two techniques were employed
    Dividing the plant
    These plants are tough – no need to use kid gloves
    • An axe and mallet were used to lever the larger divisions
    • Smaller divisions were twisted by hand
  9. Throughout the process old roots were pulled off or cut away
    • Old roots are soft, spongy and dirty looking
    • New roots were white and firm to touch – see photograph above
  10. Once the initial canes were divided they were examined for further division This decision can be a case of personal preference.
    • In the picture below this section could have been split in half but it was decided to leave as one pieceTo divide or not divide any further
  11. Next the split canes were well dusted with wettable sulphur
    • To make this easier the sulphur was put into a stocking and used like a powder puffSulphur dusting before potting (4)
  12. Before commencing the potting on, many of the dried white sheathes on the canes were removed
    • This can be a source of stagnant water collection resulting in rotting or infection
  13. Finally it came to potting on. A mixture of two types of orchid potting mix was used – Orchid Mix with fertilizer and Orchid mix with 8 – 18 mm bark
    • The reason was that the mixture needs to be open to allow air movement. Normal potting mix would be too compact. Dendrobium are epiphytes not terrestrials but they can be grown in pots.
  14. The canes were placed upright in the pot and the mix placed around.
    • As these are heavy plants, stakes were used to secure the canes upright
  15. Each plant was then labelled
    • An important process so as to not get them confused with other plants – many can look similar
    • The name and date were written on lollypop stick
  16. Finally the pots were given a light fertilizer, less than a teaspoon, and watering, then sprayed with Escar-go, a copper spray a snail and slug repellent.


Other grower may do things a little different from what is describe here but this is the method that was shown to us.

Lesson – breaking up is easy to do even if it is hard work, but worthwhile hard work.

The finished product - lots of lovely new plants!
The finished product – lots of lovely new plants!

PS – It did take three of us to do the one pot and so I would like to thank Jan and Sandra for their help.

PPS – Encouraged by how easy it was to do, the following week two of us divided two other Dendrobium –  D. speciosum and D. kingianum (white) but we only took pictures of the D. kingianum and to see what it will look like when it flowers, click here.

D kingianum composite (2)









Australian Orchids & the Doctors they Commenorate Part 12 of 20

Herman Beckler (1828 – 1914)

A general medical practitioner in Ipswich and Warwick (Queensland) and, after 1862, in Germany; in 1860, he travelled with the Burke and Wills expedition as a doctor–botanist and expeditioner in Victoria and New South Wales.

Orchid Species:

Dockrillia schoenina (= Dendrobium beckleri) or common name Pencil Orchid

Papillilabium beckleri or common name Imp Orchid

Purchasing Orchids in Victor Harbor


I missed the NOSSA Spring Show and I was wondering if there was a way of purchasing native orchids – Cym canaliculatum, non-hybrid Sarcochilus, Den falcorostrumD. ligguiforme & Bulbophyllums mainly, but also any others which will grow in shadehouse conditions in Victor Harbor?


There are several places where these orchids can be purchased.  Sizes vary so suggested you contact the growers.  Stick to larger and more established plants if you are a beginner.  Most will grow well in Victor with the milder climate.  If you get hold of Cym. canaliculatum make sure they are kept dry and under cover from April to October.

Orchids on Newbold, prop. Stephen Stebbing, can be accessed thru the net or better still, Ebay.  Only found Bulb. shepherdii on the net last night but I have seen exiguum (I got a piece) but in the way of species Dendrobium he has cucumerinum, pugioniforme, tertagonum, linguiformis, schoeninum, striolatum ( various clones of the species).  Has plenty of Sarcochilus but mostly hybrids, would suggest though he would have some of the typical species such as hartmanii, fitzgeraldii.  He does have the Cymbidium species such as suave and maddidum but doubtful  about canaliculatum.

Fernacres Nursery in Victoria deals will bush salvaged species from logging areas.  Mostly sold bare root but has good sized plants for reasonable prices.  This will be a better bet for picking up Den. falcorostrum and those mentioned above.  They may have cannaliculatum.

The Rock Lily Man (Gerry Walsh) I know was selling sizeable clumps of established bush salvaged falcorostrum recently and should still have a few left.  He has fabulous Den. speciosum available but be prepared to pay good dollars for show bench stuff.

Australian Orchid Nursery (Wayne Turville) specialises in natives but has moved a bit more towards Cymbidiums.  His mounted plants are first class and I know from time to time he has some of the other Bulbophyllums.

You can always ask them for other species.  They don’t always list everything and may have a piece or two of the lesser species lying around that they don’t list.

Most of these growers usually have links to other nurseries so with a bit of homework you can usually always get what you want.