Handbook of Vanilla Science and Technology

The specific conditions that V. planifolia prefers are:

• shade/filtered light around 50%;

• daytime maximum temperatures between 21 and 29°C;

• night-time minimum temperature of about 16°C;

• 65 to 85% relative humidity; and

• soil medium that is moist (but not soggy), well drained, and rich in mulch.

There are two distinct regions, which are climatically suitable for the cultivation of vanilla (Figure 5.1). The first is the Darwin region and the Top End of the Northern Territory, extending as far south as possibly Katherine and to the east Arnhem Land, up to 200 km from the coast, providing suitable ground water is available for irrigation. The other is a coastal strip of far north Queensland beginning from Mackay, stretching north to the tip of Cape York. The strip spreading from the coast inland to the ranges includes regional centers such as Cairns and Townsville.

Fig. 5.1 Reg ions of Australia suitable for cultivation of vanilla.

5.5 CLIMATIC CONDITIONS IN THE VANILLA GROWING REGIONS

Both the far north Queensland and Top End regions of Australia have a tropical climate, with hot humid summers and mild dry winters (http://www.bom.gov.au/weather/qld/cairns/climate.shtml; http://www.darwin.nt.gov.au/aboutdarwin/darwins_profile/climate.htm). Rains occur mainly during the summer months between December and March. The average annual rainfall is approximately 1,700-2,000 mm. The temperatures in these areas are typically uniform throughout the year with daytime temperature ranges of 23 to 33°C in summer and 18 to 30°C in winter.

5.6 SOIL AND NUTRIENTS

Growth of vanilla in a shade house system, with the use of raised mulch beds and timber posts and trellis supports, allows suitable conditions to be established and managed more readily. In Darwin, a typically two layer system of preparing the raised mulch bed for planting is used. The 2 to 3 inches thick (50-75 mm) bottom layer consists of 50% rich organic compost and 50% coarse hardwood wood chips (e.g. red gum or similar). The upper layer is either red gum wood chips or a blend consisting of a minimum of 80% red gum wood chips with up to 20% charcoal. This mixture provides the balance between moisture retention, aeration, and drainage in which the vines thrive.

5.7 WATERING

As in the wild, V. planifolia is commercially grown in areas with a high annual rainfall (1,800-2,500 mm) spread throughout most of the year. It is important that the plants be kept moist. Vanilla prefers a well-drained growing medium, and does not like to be constantly wet. Drying out completely should be avoided. Vanilla requires a dry season of a minimum of 2 months to encourage flowering in the coming summer. In Darwin this period occurs June to August. The extended dry season in Darwin necessitates the need for irrigation, which also aids in maintaining appropriate humidity levels.

5.8 FERTILIZING

V. planifolia benefits from foliar feeding. A weak fish emulsion based liquid fertilizer added to the water spray (irrigation system) is suitable. The weak (a quarter of the recommended strength) fish emulsion based liquid fertilizer provides a complete food for the vines and seems to work best if applied late in the day, ideally just after dusk.

Vanilla appears to have few insect pests in northern Australia, making it naturally suited to organic/bio-dynamic cultivation. The little damage very occasionally done by insects can be easily tolerated for the operation and business benefits that organic certified production may offer. To this end vanilla may be seen as friendly to native species of fauna due to its production potentially being chemical free. Its relatively small foot print means growers may be able to retain or replant native forests or woodlands, benefiting local wildlife and the climate.

5.9 PROPAGATION

The propagation of all vanilla in Australia is predominantly done by cuttings from healthy vines. With limited stock available, consideration has been given to importing plant material (cuttings) from the Indian Ocean. This is a time consuming and costly exercise due to Australia’s strict quarantine requirements. Import conditions require all cuttings to be fumigated and planted out in an approved quarantine facility at the importers expense for a period of 3 months.

5.10 SUPPORT