Growing Tropicool™ Dendrobiums

Tropicool™ is a registered trademark that belongs to Down Under Native Orchids and refers to the group of Australian native orchid hybrids with a percentage of Dendrobium bigibbum in their background; (they have also been called hot/colds). The percentage of Dendrobium bigibbum may be from as little as 6% too as much as 25%.

Dendrobium bigibbum flowers in autumn unlike most other commonly used species, which flower in spring. Tropicool™ Dendrobiums can flower any time from February to October and in some cases three or even four times a year, with their peak being between July and September.

Due to the Dendrobium bigibbum influence the flowering season is extended, over coming the problem of a short flowering duration, experienced by the traditional Australian native epiphytes. Another important factor in growing Tropicool™ Dendrobiums is that they will usually flower a year before other Australian native hybrids which need the new bulb to have a nine month maturing period. Thus, the "no maturing period required" feature of the Tropicool™ Dendrobiums is a big plus. Furthermore on most Tropicool™ Dendrobiums you will find that they will multi-spike with any thing from 5-6 inflorescences coming from one pseudobulb so that with judicious back-cutting on a mature plant you can turn it into a magnificent specimen in a relative short time.

Dendrobium bigibbum includes all the plants that are grouped in the Dendrobium phalaenopsis group, which includes the following; Dendrobium bigibbum, Dendrobium lithocola, Dendrobium compactum and Dendrobium striaenopsis.

With the Dendrobium bigibbum parentage in mind you have to grow these slightly different to the normal Aussie Dendrobiums. Remember where Dendrobium bigibbum grows in the wild, in a belt from Cairns to north of Cooktown and this is the area of the monsoon, hot humid summers of heavy rains daily but in winter a definite rest period with little or no water.

So with the above in mind we grow Tropicool™ Dendrobiums in a very open, free draining mix. In a pot that is not too large and that has good drainage. We use and recommend ‘Port Pots’, ‘Dome’ pots and ‘GCP’ pots (in sizes 100 to 140mm in size). We use medium bark and 20% styrene foam beads as a mix, and keep the Tropicool™ Dendrobiums separately on a bench and hanging so that during the winter they get watered only half as much as the other Dendrobiums.

Our mix, that I learned when I was helping Phil Spence repot, is as follows

Before potting sieve the mix and remove all fines, stones, wood and skins. Wet the bark, add the styrene beads and re-wet all with a hand sprayer. Sprinkle a little ‘pinch’ over it and mix the bark around thoroughly until all is covered. Now you’re ready to pot up, just hold the plant in place and pour the mix in and tap on the sides of the pot to settle. If you need to, use a stake or a hanger to keep the plant from moving until it gets new roots into the mix. Do not push down the mix. Water heavily and place on the bench. Large Tropicool™ Dendrobiums love to be hung up under fairly bright light.

Best of growing.

Bill Dobson

Elanbee Orchids