Growing Dendrobium kingianum in Adelaide 1983 and Now

In 1983, Ron Robjohns, NOSSA’s first treasurer, wrote a comprehensive series of articles about growing epiphytes in South Australia. Thirty years on Ron’s information for growing is still helpful and applicable for today. Any updates or extra information are in black text.

NATIVE ORCHID SOCIETY OF SOUTH AUSTRALIA JOURNAL Volume 7, No. 3, April, 1983

GROWING EPIPHYTIC ORCHIDS IN SOUTH AUSTRALIA – R.T. Robjohns

Dendrobium kingianum (Pink Rock Lily)

This is possibly the best known and most variable of our native epiphytic orchids. Its range is along the coastal strip from the Hunter River in New South Wales to Rockhampton in Queensland. While it is principally a lithophyte and found growing in large mats on exposed rock faces, it is also found in shady gullies and on trees.

It has three to six lanceolate leaves up to 13 cm long on stems varying from slender stems, pseudo bulbous only at the base, to short stout pseudo-bulbous stems. The pseudobulbs are usually 8 to 10 cm long with some up to 30 cm in length; the colour varying from pale green to dark reddish green. One to three racemes of up to twelve flowers, often fragrant, are borne from the top of the pseudobulbs, the colour, while commonly pink, varies from white to purple. They are up to 25 mm in diameter having the labellum usually spotted and blotched with mauve. The flowering season is August to November.

It can be grown on slabs or trees (e.g. Jacaranda or Melaleuca) but locally, best results are obtained from pot culture – rafts or hanging baskets, using an open mix. Some growers use a commercial cymbidium mixture.

I have had good results by lining wire baskets with a thick layer of live spagnum moss and filling them with small pieces of seasoned pine bark and charcoal. I find that the plant not only grows up but also out of the sides of the basket.

Some shade is required in our summer I have had success using 50% shadecloth. Protection from our winter frosts is also necessary. Fertilise lightly in the growing season using commercial fertilisers at half strength.

Being hardy it is well suited to cultivation and hybridisation. D. x delicatum is a natural hybrid of D. speciosum and D. kingianum, also D. x suffusum is a natural hybrid of D. gracilicaule and D. kingianum.

A number of man-made hybrids are available. Some of the best known are D. Bardo Rose (D. kingianum x D. falcorostrum). D. Ella Victoria Leaney (D. kingianum x D. tetragonum), all of which respond well to pot culture and flower freely.*

Propagation is either by division or cultivation of “keikies”.

Drawing of Dendrobium kingianum
Drawing of Dendrobium kingianum

*The number of hybrids has increased since 1983.

Growing Epiphytic Orchids in Adelaide 1983 and Now

In 1983, Ron Robjohns, NOSSA’s first treasurer, wrote a comprehensive series of articles about growing epiphytes in South Australia. Thirty years on Ron’s information for growing is still helpful and applicable for today. Any updates or extra information are in black text.

NATIVE ORCHID SOCIETY OF SOUTH AUSTRALIA JOURNAL

Volume 7, No. 3, April, 1983

GROWING EPIPHYTIC ORCHIDS IN SOUTH AUSTRALIA – R.T. Robjohns

Epiphytes usually grow where there is plenty of air movement, ample light but also shade and to achieve this they are frequently found well above the ground storey in the forest from where, should they be dislodged from their host and fall to the forest floor they wither and die. With most plants the roots grow downwards, however, with epiphytes in their natural habitat, the roots may grow up, down or around their host, that is, in any direction in search of suitable conditions.

As a novice grower I urge you to learn all you can about the natural habitat of the plant and its principal host, bearing in mind that in accounts of plants that grow on rock faces, often they are growing with their roots in crevices into which any moisture drains and maybe in an accumulation of leaf litter. Frequently the rocks on which the lithophytic orchids grow are sandstone – a rock which can absorb moisture and consequently keeps cool longer than most other rocks. “In an exposed situation” should not be construed as being in full sun all of the time: usually they receive some shade.

With the possible exception of Cymbidium canaliculatum few epiphytes grow at their best in full sun in nature. Full sun in the hot dry South Australian summer will usually burn off the plants or at the best cause severe yellowing and loss of leaves. It is to be noted that this State has no native epiphytic orchids.

Most Australian epiphytic orchids grow in the coastal belt of northern New South Wales and Queensland where the average rainfall in their DRY season is much the same as the Adelaide winter or WET season with which it coincides, consequently advice that plants require to dry out during the winter should not be taken to the extreme and the plants left without water.

The three principal requirements of epiphytes are a free air circulation, a semi-shaded position and free drainage.

In South Australia epiphytes are grown in two ways, the most popular being pot culture and the other slab culture.

For pot culture the medium must be a free draining one and a mixture of “aged” pinebark, scoria and charcoal is quite effective.

Note 2015 – Today the potting media used is composted pine bark.  Charcoal is not used and scoria can get cold and wet in winter.

In choosing material for slab culture consider the conditions under which you intend to grow the plants. For humid conditions cork is ideal while tree fern, which holds moisture longer, is good for dry conditions, although any of our native trees with papery or corky bark is suitable. Perhaps you would wish to attach the plants directly to trees in your garden, for this purpose try Jacaranda, Melaleuca or trees with a similar bark.

Watering is important, slab culture requires more watering than pot culture and in summer water orchids on slabs at least every second day and every-day during a hot spell. Water according to the weather and watch for signs of stress – in wintertime the rain is usually sufficient.

Fertilising is best done using half of the recommended strength of commercial proprietary fertilisers.

As a last general recommendation – beware of frosts. Last year (1982) the frosts in some areas of Adelaide caused severe losses amongst plants of epiphytic native orchids. Large tubs of D*. speciosum, whose thick leathery leaves I mistakenly thought frost resistant, were reduced to a mass of leafless canes; even baskets of D. kingianum hanging three feet below the 50% shadecloth had all of the leaves burnt off. These were but two of the varieties which suffered, so be warned and ensure that your plants are protected from frosts.

*D. = Dendrobium

Dendrobium speciosum
Dendrobium speciosum in culture

 

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.

Orchids

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)