Queensland Nut Macadamia integrifolia

Macadamia Nut is a large, broad leaf evergreen tree in the wintergreen family and native to the rain forests of New South Wales in the south eastern corner of Australia. It was introduced to Hawaii from which most of the commercial nuts come from today. The tree is an attractive evergreen and can make a good shade and flowering tree. At maturity, it will reach a height of 50 feet and a spread of 40 fee. The large leaves occur in whorls and the pink fragrant flowers are in drooping clusters. The genus name honors John Macadam (1827-1865), a chemist and lecturer in Melborne, Australia. The species name means with entire or uncut leaves.

There are two species of macadamia nuts grown today: M. integrifolia is the most common and has a smooth shell while M. teteraphylla has a rough shell.

Macadamia Nut trees prefer humus-rich, moist, well drained soils in full sun and are intolerant of frost. They need lots of water when young, but become drought tolerant with age. In its natural habitat, young trees benefit from a consistent rainfall of 50 inches per year. The tree will start producing fruit at 6 to 7 years of age.

In colder climates, it can be grown in a pot and brought into a greenhouse in the winter.  The tree should also be planted in a site that protects it from strong winds. Ingesting parts of this tree can cause depression, hyperthermia, weakness, muscular stiffness, vomiting, tremors, and increased heart rate in dogs.

Insects, Diseases, and Other Plant Problems: 

The trees in Australia have been affected by fungal pathogens that cause flower blight.