The Wanneroo Orchid Society

                                  AUSTRALIAN NATIVE ORCHIDS

                            DENDROBIUMS             &                SARCOCHILUS

The Australian native orchids mostly grown by orchid growers are Dendrobium

and to a lesser degree Sarcochilus.

Firstly don't let the big names put you off, Dendrobiums are pronounced

Den dro bee ums and Sarcochilus Sar co chil us. 

Now that we have got that out of the way we can carry on, now you know what

you are reading about.

DENDROBIUMS

Dendrobiums have canes or stalks varying from short, about 10cm tall to longer

up to about, usually 40-50cm, but in the case of one Dendrobium species 100cm,

and one of the Queensland Dendrobiums can grow up to 200cm or more. ( It would

be doubtful if you would find one this big in cultivation) They vary in thickness from

about 5mm diameter up to 4 or 5 cm diameter as in the case of the larger

Dendrobium speciosums.

They grow easily in our backyards in Perth with some protection from our fierce

summer sun. They do not flower if kept in full shade, but relish about 50% sunshine

in summer, ie under a tree with mottled light or in a shadehouse with 50% shade-

cloth. If you grow ferns in a shade house and they are growing well, then your

Australian native orchids will not flower very well if at all as it will be too shaded,

they need more sunshine than ferns. In winter they do well if put out in full sun and

watered, only if we have a long dry spell, a week or two without water in winter will

not worry them, in fact I find it beneficial. I do not water mine at all once I have

put them in full sun after the last of the 30 degree days are finished. In autumn and

winter I leave it to the rain to do the watering, except if we have not had rain for

two to three weeks. In summer, owing to the very porous mixture, they should be

watered every day or every 2 days. 

They are not fussy about fertiliser, liquid fertilisers are OK as is slow release

or even Dynamic Lifter and sheep manure. If you use slow release try to use it so

that fertiliser is finished 2 to 3 months before flowering is due. Very probably you

would have bought your Aussie Native in flower so it will flower again next year at

this time all things being equal and correct. If you use liquid fertiliser try to use a

balanced fertiliser in preference to a high nitrogen. If you use Dynamic Lifter or

sheep manure it will cause the bark mixture to rot quicker and you will have to

repot sooner than if you use liquid or slow release.

The potting mix used for these orchids is usually exclusively pine bark graded to a

size to suit the plant and you may find some blue metal stones mixed with the bark.

The blue metal is thought by growers to help dry the mix after watering. As these

plants originally grew on trees as, what is called "Epiphytes" (not parasites) their

roots dry out fairly quickly after rain. When Dendrobiums and Sarcochilus are

watered in pots in pine bark the water can quickly drain away and allow the roots

to dry out some.

Repotting should ideally be carried out when the plant has finished flowering,

but please remember these plants do not need large pots until they become large

plants.

A plant growing well and about 10 years old could still be growing in a 10 or 15cm 

pot and still not need repotting. The bark should be clean and not have any soil

mixed with it or it will stay wet and cause the roots to rot, causing the plant to wilt

and the canes to shrivel as if it has not been watered (The rotten roots cannot

supply the plant with moisture). The best bark can be obtained from a specialist

Orchid nursery such as Ezy Grow or Wonderwest and is labeled Aussie Bark or

Debco bark. If you are worried about repotting or any other problems the

Wanneroo Orchid Society hold a workshop every year, usually the first Sunday

in October at the Robinson pavilion in the Osborne Park Showgrounds. At the

workshop you can have your plant repotted by an expert and be shown how it

should be done.

Continued