Steve Howard writes cultural notes for Adelaide conditions. These are his notes for August; for both epiphytes and terrestrials.
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.
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.
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
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.
Steve Howard regularly writes orchid cultural notes for various orchid clubs in South Australia. His notes are tailored specifically conditions in Adelaide. The following are his notes for both epiphytes and terrestrials for the month of July.
Water mounted native epiphytes daily; pots weekly and small pots twice weekly depending on the weather. Hot cold types require drier conditions. Generally none to once monthly for me.
Colder weather slows down their metabolism in winter. Foliar feeding is beneficial.
Keep water out of new growths to avoid rot. Clones prone to this need to be moved under hard roof cover to keep drier.
Check under leaves for scale.
Weed pots as the weeds appear and ensure that they don’t get too wet.
Remove rotted growths.
Start baiting for slugs and snails as spikes emerge from protective sheaths.
Provide hard cover during wet weather to stop botrytis spotting and rotting out spikes.
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.