Cymbidium canaliculatum

by Roger Herraman

Cym. canaliculatum is one of only three species within the genus that are endemic to Australia. With its precisely arranged racemes of small flowers in a variety of colours and patterns, it has always held a special place of interest for me in 35 years of orchid growing. It has its own unique growing requirements which, in itself, can present a challenge (especially when grown well away from its natural habitat).

Over the years I have been able to build up a reasonable collection of plants which demonstrate the variability within the species. The strikingly different clones of the northern Australia 'Sparkesii' form could easily make a wonderful collection on its own. Southern forms vary in colour from white through to yellow and the relatively common green-brown, all with differing degrees of markings and colour intensity. There is also an alba form with apple-green petals and sepals and a pure white lip.

Being a predominantly inland species, it requires a much drier cultural environment than either Cym. suave or Cym. madidum. I have seen it growing as far south as the Ardlethan area in southern New South Wales, with reported sightings even further south around Hay. Its province stretches from this general area up through central and northern NSW into Queensland to Cape York Peninsula, then across the Gulf country into Arnhem Land and as far west as the Derby area in Western Australia. In eastern Australia it is almost always located on the drier western flank of the Great Dividing Ranges. In far north Queensland, it may be found much closer to the coast. This environment gives an immediate indication to its cultural needs. While its southern occurrences would endure cold winters and hot dry summers, the northern forms thrive under warmer conditions overall but with pronounced wet and dry seasons.

My plants are housed in a pitch-roofed polycarbonate enclosed structure with no shadecloth canopy. The manufacturer claims a 55% light transmission which should equate to 45% shade. This seems to suit the plants well as I have not experienced any burning on those hanging with leaves less than 30cm from the roof, even in extreme heatwave conditions (>40°C). These temperatures are not uncommon in Adelaide over several days at a time during summer with associated very low humidity of 10 to 15%. The majority of plants are suspended more than 2 metres above the ground with only the larger pots and striking backbulbs benched about 90 cm high (I don't like bending!). Watering is only done weekly during the growing season (November to late April in Adelaide) and plants are fertilized fortnightly during this period with a dilute variety of mainly organic low nitrogen fertilizers.

The slightly alkaline mains water in Adelaide seems to suit them, as I do not lime the plants as many growers in the eastern states must. I occasionally flush the collection with rainwater over summer to reduce the build-up of unwanted salts in the pots. During the period from Easter to mid-October, water is withheld almost completely apart from perhaps an occasional light splash if we are lucky enough to have a mild winter. Temperatures inside the growing house range from about 3°C on cold winter nights to over 45°C on those hot summer days. I do not grow any other genera in the area set aside for Cym. canaliculatum. This allows me to care for them separately and not have to worry about other plants receiving too little water and humidity.

On extremely hot days I occasionally give the plants a mist, mainly to lower the inside temperature. Louvre windows on the northern and western sides of the house provide ample air movement with hot air escaping through the ridge cap. The house is not sealed in any way from the extremes of weather. Potting mix consists of medium grade pine bark with a few pieces of large grade in the bottom of the pot, river gravel and a little Maidenwell to help conserve moisture. I occasionally add a small quantity of ti-tree or eucalypt mulch to the mix if it is available at the time of preparing my mix. I try to use deep pots whenever possible. Potting is an infrequent chore for Cym. canaliculatum, with most plants being repotted or potted on every three or four years. They do not seem to enjoy being divided too often as you sometimes may have to wait two to three years before they bloom again.

Flowering time in Adelaide generally begins in late October with the southern forms opening first and extends well into the new year with some of the hybrids like Cym. Little Black Sambo and Cym. Kuranda. The darker 'Sparkesii' forms are the latest to open around mid to late November. I find the hybrids to be very long lasting in my growing area, often staying in good condition for more than two months. I do not know of many orchids that possess this longevity of blooms at this time of the year when they are subjected to such high temperatures.

I attempted some pollinations during the last flowering season to see whether I could, perhaps, eventually produce some improvements or greater variety of colour and markings within the species. I tried about 20 reverse crosses using a variety of clones. So far about 30 pods are still swelling approximately ten weeks after pollination.

There are not many hybrids around using Cym. canaliculatum, but the grexes of Cym. Little Black Sambo (canaliculatum x madidum), Cym. Pied Piper (devonianum x canaliculatum) and Cym. Brown Beauty (canaliculatum x floribundum) are well worth having in your collection. I have three distinctly different clones of Cym. Little Black Sambo. I imagine the differences in flower colour has come from the various clones of Cym. canaliculatum used.

Another interesting hybrid is Cym. Australian Midnight (atropurpureum x canaliculatum) with its very dark flowers and late flowering (December/January in Adelaide). When crossed back to Cym. canaliculatum (= Son of Midnight), the resultant flowers are much improved in shape and just as dark. These hybrids are grown in the same area as the species and treated similarly.

Cym. James Webeck (canaliculatum x suave) is a hybrid I have never been able to obtain, so I thought I would try to make it myself. I had previously been told by a number of respected hybridists and experienced growers that Cym. canaliculatum is a notoriously poor pod parent while being a good pollen provider. With this in mind I made another 20 reverse crosses using three different Cym. suave clones and the same Cym. canaliculatum plants as before. To my amazement, after ten weeks, every attempt on various Cym. suave plants had aborted and only about five dropped from the various Cym. canaliculatum plants. I realise that they still have a very long way to go to reach maturity and anything could happen during the interim period, but the initial signs are, at least, promising. So much for "expert advice"!

The accompanying photos are of some clones that have flowered in recent years in my orchid house. Last season was particularly good in Adelaide for reasons unknown to me. Perhaps it was that many plants matured their season's new growth rather early last year with a longer than usual dormant period to follow. I cannot think of any other feature that was different about the season or my culture.

So, if you like a challenge and are not too heavy-handed with the hose, try a few Cym. canaliculatum varieties. You will surely be rewarded with some exquisite blooms in a great variety of colours and forms at a time of the year when most Cymbidium hybrids are all but finished.

Good growing,
Roger Herraman