Araucaria Bidwillii - Cultivation

Cultivation

Bunya nuts are slow to germinate. A set of 12 seeds sown in Melbourne took an average of about six months to germinate (with the first germinating in 3 months) and only developed roots after 1 year. The first leaves form a rosette and are dark brown. The leaves only turn green once the first stem branch occurs. Unlike the mature leaves, the young leaves are relatively soft. As the leaves age they become very hard and sharp.

In the highly variable Australian climate, the spread of actual emergence of the bunya maximises the possibility of at least successful replacement of the parent tree. A test of germination was carried out by Smith starting in 1999. Seeds were extracted from two mature cones collected from the same tree, a cultivated specimen at Petrie, just north of Brisbane (originally the homestead of Thomas Petrie, the son of the first European to report the species). One hundred apparently full seeds were selected and planted into 30 cm by 12 cm plastic tubes commercially filled with sterile potting mix in early February 1999. These were then placed in a shaded area and watered weekly. Four tubes were lost due to being knocked over. A total of the 100 seeds placed 87 germinated. The tubes were checked monthly for emergence over 3 years. Of these seeds, 55 cones emerged from each month from April to December, 1999; 32 emerged from January to September in 2000 and 1 seed emerged in January 2001 and the last 1 appeared in February 2001.

Once established bunyas are quite hardy and can be grown as far south as Hobart in Australia (42° S) and Christchurch in New Zealand (43° S) and (at least) as far north as Sacramento in California (38° N) and Lisbon (in the botanical garden) and even in Dublin area in Ireland (53ºN) in a microclimate protected from arctic winds and moderated by the Gulf Stream. They will reach a height of 35 to 40 metres, and live for about 500 years.