Orchid Growing Information > Growing Dendrobium Speciosum

Growing Dendrobium Speciosum

Once in a past life when I was a beginning native dendrobium hybridist emeritus AOC judge Gordon Giles said something to the effect that "the trouble with you native breeders is that you muck around in your backyards with your toothpicks and you still haven't come up with a hybrid that is as good as a decent speciosum". Although this observation rankled a bit at the time I think I know what he was getting at. 'Rock Lilies' can reliably produce long racemes of relatively large white, cream or yellow flowers late in winter or spring and, being native to most of the Australian east coast, will thrive in their home range given minimum care. Dendrobium speciosum Var. speciosum 'National White' HCC/OSNSW is definitely my favourite native and possibly my favourite orchid overall even though there are probably 'better' clones around.

Den. speciosum 'Kayla'Den. speciosum does best when given a little protection from the weather extremes of the increasingly angry summer sun and biting winter frosts but even then they will survive these tortures looking only a little worse for wear as a result. There is no need to molly coddle these workhorses like some of the newer temperature and water sensitive hybrids! The ideal situation would be where they receive sun from dawn to sundown under 50% shadecloth on benches that enable some degree of control over slugs and snails.

For many years I have grown them in a mix of treated pine bark and river pebbles of a fairly coarse grade and had good results. They seem to do a little better in cement or terra cotta pots but these have largely been replaced in my collection by plastic Port Pots for reasons of cost and practicality. Wayne Turville in Melbourne has excellent growth in hollowed out treefern trunks, they were growing so well when I visited his nursery that I wondered at the time if he would need a forklift to move them. I am currently experimenting with a cocochip and Maidenwell stone mix and the early indications are of excellent root growth, I hope that this material will last for at least a couple of years. Remember if you use cocochips that it is devoid of calcium so you will need to add it in some form without raising the ph too much - dolomite or calcium nitrate may be useful for this.

These plants are not fussy eaters and any soluble fertiliser, blood and bone, Dynamic Lifter or similar served up in small doses from after flowering through to January will be appreciated. Garden specimens survive in rockeries with little extra feed while some growers employ heavy feeding programs but this tends to result in oversized growth in plants that can often assume large dimensions without any extra encouragement. The greater danger is to try and spoil them too much water and fertilizer which often ends in disaster.

I am not the only one who loves the 'King Orchid', many growers are coming to appreciate its virtues especially in the USA where, as the stories go, large consignments of speciosum have ended up (at fairly attractive prices too!). There is even a specifically dedicated speciosum show held every year on the NSW mid north coast each year. Unfortunately humans are not the only creatures that have an appetite for Rock Lilies and dendrobium (orchid) beetles love to eat the flowers, seed pods and new leaves while their larvae can often be found on or in any juicy new part of the plant converting plant tissue into slimy jelly. Aphids and snails will enjoy the flowering season just as much as you if you are not careful while longicorn beetles don't mind tunnelling down the centre of the canes at any stage of growth. A bug proof shadehouse and vigilant hunting are usually enough to minimise the problem without having to resort to chemicals.

Dendrobium speciosum is very adaptable to a variety of growing situations and in the greenhouse can be grown in pots, on mounts or in hanging baskets while in the garden it will grow on trees, rocks, concrete walls or strategically positioned in pockets in rockeries. A walk around most of the streets of Sydney's older suburbs in September will reveal a surprisingly large number of rock lilies flowering their heads off, doing it tough and providing a haven for dendrobium beetles

The most common complaint about growing speciosum is that they take too long to flower from seedlings. We've all heard the "I'll be dead before it flowers" whinge. What these defeatists do not appreciate is that a well cultured plant will flower in five to six years, a time frame comparable with many other orchid genera. The 'twenty years to flower' myth has been based on a few degenerative individuals (how many of us have a plant or two of other genera that we can't flower?) or on a past era when they were poorly regarded as "just rock lilies" and neglected in a corner of the greenhouse and afforded little encouragement to develop quickly.

Yes, I think Gordon Giles was onto something. There seems to be a shortage of native hybrids that will tolerate the rough treatment given to many speciosums and still produce massive racemes of large flowers..but then again some people don't only like white, cream or yellow flowers.

Bibliography

  • Australian Indigenous Orchids (Vol. 1) - A. Dockrill
  • Native Orchids Of Australia - David L. Jones
  • Dendobium And Its Relatives - B. Lavarack, W. Harris & G. Stocker
  • Dendrobium Orchids Of Ausralia - W. T. Upton

Neville Roper
August 2006